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Catalytic ozonation is potential to eliminate sulfur-containing organic compounds (S-VOCs) with anti-poisoning of sulfur at low temperature. This paper synthesized a popcorn-like catalyst Mn@ZSM293 with confined effect that could combine with ozone to attain 100% conversion of CH 3 SH at low temperature, ca. 15 °C, with a low O 3 /CH 3 SH molar ratio of 1.33. Particularly, excellent stability without sulfur poisoning and good water resistance were observed. By contrast, Mn/ZSM293 exhibited agglomeration of Mn nanoparticles that displayed only 70% conversion at same condition and suffered deactivation. Mn@ZSM293 possessed the structures with well-defined large internal voids and surface etchings, which promoted metal-support interaction. The confined effects also brought more oxygen vacancies, larger surface area and pore size, as well as stronger acidity. These properties were favorable for CH 3 SH adsorption, activation and breakage of C−C and C−S bonds. CH 3 S−, CH 3 SO 3 −, SO 4 2−, and HCOO− based compounds were detected as the critical products by in-situ measurement. [Display omitted] • A popcorn-like confined Mn@ZSM293 was synthesized for catalytic ozonation of CH 3 SH. • CH 3 SH attained complete conversion at 15 ℃ with the O 3 /CH 3 SH molar ratio of 1.33. • Mn@ZSM293 performed excellent stability and exhibited resistance under 10 vol% H 2 O. • The confined structure caused strong metal-support interaction, abundant oxygen vacancies, and acidity. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is the main way of lignocellulosic biomass utilization, while the management of digestate from AD has been a major obstacle to the sustainable operation of AD plants. The traditional agricultural application of digestate is restricted due to seasonal and biodegradation limitations. Thermochemical processing can be used as an alternative technology to continuously manage large-scale concentrated AD digestate. This review outlined the current thermochemical technologies for digestate treatment, which are mainly divided into two types: one-pot method (i.e., unseparated solid liquid fraction) and separated treatment of solid digestate. The principle, advantages, bottlenecks, products and application scenarios involved in each thermochemical processing of digestate are provided. In summary, the former saves the energy consumption of solid-liquid separation, but needs to consider the heating of moisture in the thermochemical process; The latter can remove moisture before thermochemical processing, but adds a dehydration unit. Non-negligible costs and immature technologies still restrict the development of commercial for both approaches. Moreover, further integrated strategies for AD and thermochemical technologies are envisaged based on efficient biorefinery and circular economy perspectives. • The management of digestate has been a major obstacle for anaerobic digestion (AD). • Thermochemical processing was proposed as a cascaded augmentation of AD. • Product extraction and heating are the main obstacles to the one-pot method. • Integrated strategies for AD and thermochemical technologies are envisaged. [ABSTRACT FROM AUTHOR]

In this work, cattle manure and corn cob were investigated by co-hydrothermal liquefaction and the synergetic effect were analyzed. The co-hydrothermal liquefaction of cattle manure and corn cob could improve the yields of biocrude and water soluble organic matter (WSOM), but inhibit the formation of solid products. When the cattle manure content was 40 %, synergistic coefficients reached the maximum of 4.7 % for biocrude at 360 °C and 49.6 % for WSOM at 340 °C, respectively. The biocrude from co-liquefaction had lower oxygen and nitrogen contents and higher HHVs than expected. It was because the co-liquefaction could enhance the generation of phenols in biocrude and promote the migration of N into WSOM by forming 3-pyridinol, which were beneficial to increase the quality of biocrude. According to PCA analysis, most cyclopentenones showed strong correlation with N-heterocycles. In addition, with the gradual decrease of the number of substituents on the benzene ring, the correlation between aromatic compounds and protein products gradually increased, suggesting that protein content helps to promote further decomposition reactions of lignin products in co-hydrothermal liquefaction. Base on the pathway changes of cattle manure and corn cob in co-hydrothermal liquefaction, a predicted synergistic reaction network was proposed. [Display omitted] • Co-HTL of cattle manure and corn cob can increase the yields of biocrude and WSOM. • The maximum synergistic coefficient was obtained at the mixed ratio of 4:6. • Co-HTL promoted the generation of phenols, benzenediols and 3-pyridinol. • Cyclopentenones showed strong correlation with N-heterocycles by PCA analysis. • A predicted synergistic reaction network base on pathway changes was proposed. [ABSTRACT FROM AUTHOR]

• Cattle manure and corn cob showed different trends in bio-oil yield. • Co-liquefaction could improve the quality of bio-oil and increase the yields and WSOM. • The aqueous phase for corn cob was acidic but that for cattle manure was alkali. • A primary reaction network of corncob and cattle manure was proposed. Agricultural waste is a good choice to produce biofuels because of its abundance and environmental friendliness. In this work, corn cob and cattle manure were studied by hydrothermal liquefaction (HTL) in a batch reactor with reaction temperatures from 300 °C to 360 °C alone and in mixtures. HTL products, including bio-oil, aqueous phase, and gas were comparatively analyzed. The maximum bio-oil yields were 22.2% at 300 °C for corn cob and 19.3 % at 360 °C for cattle manure, respectively. Besides, the bio-oil from cattle manure had lower oxygen, higher H/C ratios, and higher HHVs than that from corn cob. N-Heterocycles could be taken as the characteristic compounds of bio-oils from cattle manure, yet organic acids and aldehydes were only detected from corn cob. Although benzenediols and N-heterocycles were major products in water-soluble organic matter (WSOM) for both two feedstocks, the pH values of aqueous phase products are acidic for corn cob and alkali for cattle manure, respectively. This is attributed to the generation of some ammonia from the decomposition of protein in cattle manure pyrolysis. The synergistic effect in mixtures could promote the decomposition of lignin by generating more phenols and benzenediols that improved the quality of bio-oil and increased the yields of WSOM. It could also affect the product of protein decomposition and transfer more N into the aqueous phase. The major component in the gaseous product was all CO 2. These results indicate that different compositions could not only react with each other but also change the pH values of the reaction environment and further affect the reaction pathways of other compositions. A predicted primary reaction network of different components from corncob and cattle manure in the HTL was also proposed. [ABSTRACT FROM AUTHOR]

In this work, pyrolysis experiments of ethyl valerate were performed in a flow reactor over 705–1051 K at low and atmospheric pressures and in a jet-stirred reactor over 633–1013 K at near-atmospheric pressure. Products were measured with synchrotron vacuum ultraviolet photoionization mass spectrometry in the flow reactor pyrolysis and gas chromatography in the jet-stirred reactor pyrolysis. Valeric acid and ethylene were observed as the most abundant pyrolysis products in both experiments. Laminar burning velocities of ethyl valerate/air mixtures were also measured in a high-pressure constant-volume cylindrical combustion vessel at the initial temperature of 443 K and initial pressures of 1–10 atm. A kinetic model of ethyl valerate combustion incorporated with recent theoretical progress was developed to predict the new experimental data in this work, as well as the speciation data under flame conditions and laminar burning velocities at different initial temperatures and pressures in literature. Experimental observations and modeling analyses both confirm the significant role of the intramolecular elimination reaction of ethyl valerate producing valeric acid and ethylene. In particular, this reaction has exclusive significance in decomposition of ethyl valerate under pyrolysis conditions, indicating pyrolysis experiments can provide crucial constraints for its rate constant. Subsequent decomposition reactions of valeric acid at higher temperatures enrich the intermediate pool, especially radicals, and can continue producing ethylene to make its mole fraction keep growing under the investigated temperature ranges in the jet-stirred reactor pyrolysis. Under the flame propagation conditions, C 0 C 1 reactions have the highest sensitivity coefficients to the flame propagation, while ethylene- and vinyl-involved reactions also play important roles due to the abundant production of ethylene. [ABSTRACT FROM AUTHOR]

The pyrolysis of 2-ethylfuran (EF2) in a flow reactor was studied by using synchrotron vacuum ultraviolet photoionization mass spectrometry at 846 – 1319 K and at 30 and 760 Torr. Over 20 pyrolysis products were detected and measured. A detailed kinetic model was constructed by extending the reported comprehensive 2,5-dimethylfuran model to describe the pyrolysis of EF2 and validated against the current experimental results, including methyl, 2-furylmethyl, propargyl, acetylene, ethylene, propene, ketene, 2-vinylfuran, furan/vinylketene and benzene, etc. Rate of production analysis and sensitivity analysis indicate that the main reaction pathways of EF2 pyrolysis are H-abstraction reactions forming 1-(2-furyl)ethyl and 2-(2-furyl)ethyl, unimolecular decomposition reactions forming 2-furylmethyl, and H-addition reactions forming furan and vinylketene. The corresponding products, 2-vinylfuran, 2-furylmethyl and vinylketene, etc., are indicated to be the most key products in EF2 pyrolysis. Comparisons of the formation of aromatic hydrocarbons in the pyrolysis of EF2, 2-methylfuran and 2,5-dimethylfuran show that EF2 had a lower tendency to produce aromatic soot precursors. [ABSTRACT FROM AUTHOR]

China is an agricultural country, approximately producing more than 1000 million tons of crop straw in 2018. The utilization of straw as energy can replace fossil fuels, protect environment and guarantee energy security. Biomass fuel has been regarded as renewable energy with the characteristics of carbon-neutral, and low emissions of nitrogen oxides and sulfur dioxide. Biomass molded fuel (BMF), a major type of biomass fuel, has attracted particular attention. Currently, the BMF industry in China develops slowly. To achieve the rapid and healthy development of the industry, in this paper, a three-part standard system as fuel side, production and combustion equipment side and pollutant emission side is proposed to regulate the BMF market. Simultaneously, a policy system consisting of legislation, development plans and incentive measures also is introduced to maintain policy consistency and continuity. Unlabelled Image • The development status and theoretical potential of biomass molded fuel (BMF) are discussed. • The current policies system and existed problems of BMF in China are analyzed. • New recommendations are proposed to promote the development of the BMF industry in China. [ABSTRACT FROM AUTHOR]

• Factors affecting Hg distribution during co-pyrolysis of SS and MSW are analyzed. • Blending ratio is the key factor affecting Hg distribution in char, tar and gas. • Blending ratio of 87.5 SS wt% can better enhance Hg fixation in char. • Neutral network model fits experimental data best with an accuracy of 91.08%. • Pyrolysis parameters are optimized for Hg fixation via neutral network modelling. Co-pyrolysis is a promising approach to recover energy from sewage sludge (SS) and municipal solid waste (MSW). Hg emission during this process has serious environmental risks. To reduce the environmental impact, orthogonal experiments on the blending ratio, heating rate, pyrolysis temperature, and residence time were conducted during SS and MSW co-pyrolysis. Variance analysis was used to determine the influence and synergetic effects of these factors. Multivariate nonlinear, neural network, random forest, and support vector machine models were used to simulate the Hg distribution based on four parameters, which were later optimized to optimize the Hg fixing ratio in pyrolysis char. The Hg was mainly distributed in the pyrolysis gas and char. The variance analysis results indicate that the blending ratio is the key factor influencing Hg distribution, and there is little synergetic effect among the four factors. Further experiments showed that a blending ratio of 87.5 SS wt% could enhance Hg fixation in char. The neural network model shows the best simulation performance with a mean relative error of 8.92%. The optimal parameters are a heating rate of 7 °C/min, pyrolysis temperature of 300 °C, and residence time of 10 min, resulting in a Hg fixing ratio of 25.68 wt% in pyrolysis char. The simulated Hg fixation characteristics correlate with the experimental results. This study provides insights into Hg distribution under various conditions during co-pyrolysis of SS and MSW. It is hoped that this work can contribute to the control of Hg during the waste treatment and utilization process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu-MnO@PDA@PVDF electrospinning catalytic membrane was prepared. • Favorable SMX removal was obtained by Cu-MnO@PDA@PVDF membrane/H 2 O 2 filtration. • Catalytic membrane/H 2 O 2 scheme showed membrane fouling mitigation ability. • Hydroxyl radicals played a vital role in SMX degradation. • Mn-Cu bimetallic centers endow the membrane with high reactivity towards H 2 O 2. Heterogeneous catalyst reuse and the effectiveness of hydrogen peroxide (H 2 O 2)-based advanced oxidation processes under near-neutral conditions remain an obstacle in wastewater remediation. Herein, we put forward a versatile catalytic membrane with Cu-doped MnO active layer anchoring on the polydopamine-modified electrospinning polyvinylidene fluoride (PDA@PVDF) base. The Cu-MnO@PDA@PVDF membrane was conferred admirable sulfamethoxazole (SMX) reduction (over 90% within 90 min) and clogging alleviation (relative flux recovery to 0.98) capabilities via in situ H 2 O 2 activation at pH 8, which was slightly affected by actual water background. Electron paramagnetic resonance (EPR) and trapping tests unveiled the joint contribution of •OH, O 2 •− and 1O 2 , with •OH exerting the supreme role in SMX oxidation. The inherent characteristics of dual Mn-Cu centers on the membrane surface for facilitation of electron transfer, H 2 O 2 adsorption and barrierless dissociation to •OH were further elucidated by electrochemical measurements and density functional theory (DFT) computation. Comprehensively, this study proposes a facile procedure and insights into engineering catalytic membrane coupled H 2 O 2 strategy for refractory organic treatment at ambient conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu(II)/PMS system was first applied to the upcycling of PP waste plastics. • Efficient PP conversion and selective production of ketone fuels were achieved. • Mechanism of PP oxidation by •OH-dominant active species was explored. • PP was oxidized to hydrocarbons and further converted to ketone fuels. Currently, the environmental and ecological risks associated with plastics are escalating. Conventional thermo-catalytic systems driven under harsh conditions lead to more carbon emissions. Herein, we first developed a Fenton-like system mediated by Cu(II)-activated peroxymonosulfate (PMS) for efficient conversion of polypropylene (PP) to ketone fuels (77.2 wt% conversion, 78.5 wt% selectivity) at 140 °C for 24 h. Cu(II) synergistic thermal activation achieved efficient PMS activation to produce radicals such as •OH, SO 4 •− and O 2 •−as well as 1O 2 and Cu(III). In the presence of •OH-dominated active species, PP was cleaved to hydrocarbons with the breaking of C-C bonds, and further oxidation of C-H bonds converted hydrocarbons to ketone fuels. This study enabled the conversion of plastics to chemicals under mild conditions, a significant step towards the establishment of an efficient recycling system for plastics recovery, leading to zero plastic waste and a carbon–neutral environment. [ABSTRACT FROM AUTHOR]

Pyrolysis is a potential approach for volume reduction and utilization of organic components in waste photovoltaic panels. During a usage period of 20–25 years, the physical and chemical properties of photovoltaic panels might undergo ageing and deterioration, thereby affecting their thermal decomposition characteristics. The characteristics of samples before and after ageing were studied using Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analyzer, and thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry. There were certain differences in the weight loss temperature, time, residual mass, and activation energy of the samples in the pyrolysis reaction. After ageing, the production of acetic acid and methane in ethylene vinyl acetate pyrolysis products increased, while the production of CO 2 decreased. After ageing, Tedlar-Polyethylene Terephalate-Tedlar mainly produced water, carbon dioxide, and fluorocarbon compounds, and the percentage of harmful fluorocarbon compounds in the human body increased. Cyclosiloxane, CO 2 , and hydrocarbons containing C-H bond were detected in each weight-loss stage of aged silica gel. As the heating rate changed, the amount of pyrolysis products also changed. Controlling the sample's heating rate would help to lessen the quantity of hazardous pollutants that were produced. The influence of ageing on the weight loss of mixed samples was discussed. This study seeks to give a fundamental understanding of the physicochemical properties, pyrolysis behaviour, and volatiles of samples before and after ageing, thus providing helpful insights for the final disposal or recovery of waste photovoltaic panels through pyrolysis. [Display omitted] ● Effect of aging on pyrolysis of polymer substances in waste PV panels was studied. ● Aging process changed pyrolysis products distribution of EVA, TPT, and silica gel. ● Average activation energy was decreased in EVA and TPT but increased in silica gel. ● Effect of aging on TG features of EVA, TPT, and silica gel blends was discussed. ● This work is hoped to provide insights for pyrolysis disposal of waste PV panels. [ABSTRACT FROM AUTHOR]

Biochar can be prepared from biomass through pyrolysis in a low-oxygen or anaerobic environment. The characteristics of biochar are influenced by raw materials and the specific preparation process employed. To enhance the efficacy of biochar, various modification methods can be applied. These primarily include chemical modification, physical modification, and biological modification. This paper conducts a literature review covering the period from 2018 to 2023, focusing on biochar preparation, modification methods, and environmental applications. It is a comprehensive overview of the processes involved in preparing biochar, analyzes its characteristics, and explores various modification techniques. Additionally, the paper discusses the diverse and highly efficient application of biochar in environmental remediation, with a particular emphasis on its use in soil, water, and the atmosphere. While biochar holds significant potential for environmental remediation, a thorough understanding of its mechanism in environmental applications is still lacking. Further in-depth studies are required to elucidate the complex roles biochar plays in various environmental contexts. • A summary of the application of modified biochar to soil, water, and atmosphere remediation is presented to show its remediation effect. • Alkali modification of biochar greatly enhances its specific surface area. • Metal salt modification significantly boosts oxygen-containing functional groups in biochar. • Some research directions and future perspectives for modified biochar are highlighted. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is a promising approach to dispose of biodegradable waste and wastewater, generating biogas as an alternative energy resource. This work proposed a so-called M-CADM1 for continuous anaerobic digestion simulation, which combined the machine learning and anaerobic digestion model No.1 (ADM1). The detailed reaction path and intermediate products in different stages of anaerobic digestion are specified in ADM1. The kinetic parameters were modified by machine learning. The characteristics (elemental composition) of feedstocks were used to predict kinetic parameters. A total of 75 biomass samples were used to establish for machine learning models. Five element contents (C, H, O, N, S), feedstock feed rate, and anaerobic digestion temperature were used as the input. The kinetic parameters were set as output. The sensitivities of 17 kinetic parameters were evaluated. 7 kinetic parameters with the highest sensitivities were selected as ADM1 model inputs by sensitivity analysis. The R2 and RMSE were used as the index to evaluated the accuracy of machine learning model. The best R2 and RMSE reached 0.84 and 0.196. The TIC was used as the index to evaluated the accuracy of M-CADM1. By comparing the simulated value with the experimental value, the accuracy of the overall M-CADM1 expressed by TIC of kitchen waste was 0.036. The organic acid content and pH in the reactor were considered as indicators to study the accuracy and stability of the M-CADM1. Trends in organic acids, free ammonia or hydrogen inhibition, and pH were consistent with experimental continuous anaerobic digestion results. [Display omitted] • M-CADM1 model was proposed to simulate biomass continuous anaerobic digestion. • Four machine learning models were tested for crucial kinetic parameters prediction. • Predicted kinetic parameters were embed in ADM1 for products prediction. • The R2 and RMSE for kinetic parameters predicting model reached 0.84 and 0.196. • The optimal overall TIC of established M-CADM1 model was 0.036. [ABSTRACT FROM AUTHOR]

Arundo donax, acknowledged for its elevated energy content, substantial biomass yield and rapid growth, stands as an alluring candidate for biofuel production. In this investigation, a molecular sieve-based catalyst was utilized to scrutinize the catalytic fast pyrolysis (CFP) of Arundo donax, aiming for the production of naphtha-range compounds. The study also encompassed the evaluation of pyrolysis product yields within a fixed-bed reactor. The systematic exploration included an assessment of the impacts arising from catalyst type, temperature, weight hourly space velocity (WHSV), and N 2 flow rate. The results demonstrated that at 500 °C, WHSV of 1 h−1 and N 2 flow rate of 300 ml/min, SAPO-11 exhibited a selectivity of 64.55% to naphtha-range compounds and 64.55% to isomerous naphtha-range compounds. This was in stark contrast to the control group, which contained no catalyst (with a selectivity of 41.40% and 3.19%, respectively), SAPO-41 (with a selectivity of 11.02% and 9.55%, respectively) and HZSM-5 (with a selectivity of 59.89% and 53.51%, respectively). Additionally, SAPO-11 yielded the highest bio-oil compared to other catalysts (SAPO-11 of 28.52 wt% > none of 19.48 wt% > HZSM-5 of 18.90 wt% > SAPO-41 of 13.11 wt%). The conclusions drawn from these findings imply that the synthesized SAPO-11 catalyst exhibited superior catalytic activity and isomerization proficiency in contrast to other catalysts (SAPO-41 and HZSM-5). Remarkably, under the specified conditions of SAPO-11 catalyst, temperature = 500 °C, WHSV = 1 h−1 and N 2 flow rate = 200 ml/min, the CFP process yielded a remarkable maximum absolute yield of the naphtha-range compound at 25.82 wt%, with an isomerized naphtha-range compound absolute yield of 25.35 wt%. • SAPO-11 was used for Arundo donax CFP in a fixed-bed reactor. • The conversion of Arundo donax into high-value naphtha was achieved. • SAPO-11 exhibited excellent selectivity and isomerization towards naphtha. • Optimization of multiple process parameters was carried out. [ABSTRACT FROM AUTHOR]

Heavy metal stabilization by chemical chelating agent and solidification by cement are technologies currently used to reduce the leaching of heavy metals in municipal solid waste incineration (MSWI) fly ash. This paper studied the physico-chemical properties of the fly ash, heavy metals content in the fly ash, and the leaching concentration of the heavy metals from fly ash. The effect of four chelating agents namely dithiocarbamate (1#), dithiocarbamic acid dipotassium salt (2#), amino dithiocarbamate chelating resin (3#) and thiourea (4#) on the stabilization and leaching of heavy metals were investigated. Different addition ratios (1%, 2% and 3% w/w) of the chelating agents, various curing time (7, 14, 28 days), and different amounts of the cement (10%, 15% and 20% w/w) were used in order to find the agent with the optimum stabilization and leaching of heavy metals as well as find the effect of combining the agent and cement. The results showed that the dithiocarbamate (1#) chelating agent had the best stabilizing performance due to the three-dimensional structure after their reaction. The addition of cement to the fly ash led to the immobilization of heavy metals due to the C-S-H gel formation. The technology of cement solidification and chelating agent stabilization was optimal from the point of economic cost and the complexity aspect. Image 10654 • The stabilization performance of four chemical chelating agents in MSWI fly ash was compared. • Dithiocarbamate presents the best stabilization character among the four agents. • Stabilized agents combined with solidified cements show better performance. • Cd is more difficult to stabilized/solidified than the other heavy metals. [ABSTRACT FROM AUTHOR]

The emerging application of solar power plants has led to serious waste photovoltaic module disposal problems. To address the environmental concerns associated with waste photovoltaic module disposal, this study investigates pyrolysis as a promising treatment technology and a fundamental step for various thermal chemical processes. The kinetic characteristics and pyrolysis products of ethylene vinyl acetate (EVA), Tedlar-Polyethylene Terephalate-Tedlar (TPT), and silica gel were studied using TG-FTIR-MS. The weight loss stages of EVA, TPT, and silica gel were between 300 and 510 °C, 330–520 °C, and 100–830 °C, respectively, with a total weight loss rate of 99–100%, 73–76%, and 60–62%. The reactions they experienced were acetic acid production and long chain fracture, long chain fracture and fluorocarbon compound production, polymer methyl vibration, [(CH 3) 2 SiO] cyclic compound production, Si–C bond fracture, and CO 2 production, respectively. According to the results of the two kinetic models, their average activation energies were 278-281 kJ/mol, 330-336 kJ/mol, and 187-193 kJ/mol. The products released during the pyrolysis process of the three samples were different. Among them, olefins and aromatic hydrocarbons from EVA and TPT could be used to synthesize high-molecular-weight substances. Aldehydes, fats, and esters from TPT could be used to synthesize drugs and daily necessities; hydrofluoric acid and furan were harmful to human health and the environment. Hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane from silica gel could be used to synthesize silicone polymers. The content of volatile substances during pyrolysis was related to the heating rate. The findings are expected to contribute to the development of waste photovoltaic module disposal and resource recovery through pyrolysis. [Display omitted] • Pyrolysis products and kinetic properties of EVA, TPT, and silica gel were studied. • Weight loss ranges of EVA, TPT and silica gel were different. • FWO method showed superior kinetic modelling performance of waste PV modules. • Pollutants emission risk in waste PV modules pyrolysis was discussed. • The results are benefit for disposal and resource recovery from waste PV modules. [ABSTRACT FROM AUTHOR]

Duckweed for wastewater treatment performs the characteristics of large water content and high organic component content, showing outstanding advantages in the production of bio-oil by hydrothermal liquefaction (HTL). Due to the high content of N, bio-oil cannot meet the specifications of fuel, which limits its practical application. The mechanism for the removal of N needs to be explored based on the reaction pathways. Therefore, glycine, glucose and glyceryl tridodecanoate were selected as model compounds of duckweed for wastewater treatment to investigate the reaction mechanism. The reaction of binary mixtures was evaluated to explore the synergistic effect. Compared with the reaction of individual model compounds, the higher yield of bio-oil was obtained by mixing glycine and glucose or mixing glucose and glyceryl tridodecanoate as the raw material. Compared with the individual reaction of glycine or glyceryl tridodecanoate, the distribution of products is almost unchanged for the reaction of the mixture of glycine and glyceryl tridodecanoate. However, the energy recovery (ER, 96.61%) and high calorific value (HHV, 48.04 MJ/kg) were extremely increased. Based on the product distribution and composition of simulated and actual duckweed HTL, a conclusion was drawn that the simulated duckweed HTL can represent the actual duckweed HTL. In addition, the reaction pathways for HTL of actual wastewater treated duckweed were established to point out the possible pathways for the reduction of N in bio-oil, which provides a foundation and direction for future research. • The synergistic effect between the model compounds HTL was speculated. • The reaction pathway of HTL was analyzed. • Recommendations to reduce nitrogen in bio-oil were suggested. [ABSTRACT FROM AUTHOR]

Thermal kinetic heterogeneity of mixed residual waste (RW) is a serious problem leading to unsatisfactory efficiency and stability during energy utilization processes. This work proposed a thermal kinetic parameters based classification method of RW. Considering the significant relevance between kinetic parameters and elemental compositions, the latter were used as indicators to establish the sorting principle. The proximate analysis results and kinetic parameters among the new categories were analyzed, the kinetic heterogeneity reduction performance versus the traditional classification method was compared, and the working mechanism of the proposed classification method was discussed. Three new RW categories were obtained, and the composition and kinetic parameters among these new categories have significant difference (P < 0.05). The kinetic heterogeneity was reduced compared with the traditional classification method. The absolute value of Pearson correlation coefficient between elemental composition and kinetic parameters could reach 0.8, proving the mechanism of the new classification method. The study is hopeful to facilitate efficient energy utilization of RW. [Display omitted] • A thermal kinetic parameters based classification method of RW was proposed. • The performance, potential and mechanism of the proposed method were discussed. • Significant heterogeneity in kinetic parameters among the categories were observed. • The PCC between elemental composition of RW and kinetic parameters could reach 0.8. • The results are promising to enhance energy utilization efficiency of RW. [ABSTRACT FROM AUTHOR]

The co-pyrolysis of algae and plastics shows great potential for bio-oil production. In this study, thermogravimetric analyzer was used to investigate the pyrolysis behavior of Chlorella vulgaris (CV) and polyethylene (PE) at different mixed ratios and heating rates. Their synergistic effects were discussed through kinetic and thermodynamic analyses. According to the thermogravimetric (TG) and Derivative thermogravimetric (DTG) curves, the co-pyrolysis process can be divided into five stages, corresponding to the decomposition of moisture, carbohydrates, proteins, lipids, and biochar, respectively. In the fifth stage, a clear synergistic effect is observed, with the highest ∆ TG reaching about 4%. During the co-pyrolysis process, the average activation energy of the mixtures is much lower than expected, indicating the presence of a synergistic effect in co-pyrolysis. Among them, 3CV1PE is the optimal mixing ratio, with the average activation energy of 3CV1PE being 6% lower than that of CV pyrolysis alone. The master plots revealed that the power law reaction models (P3 and P4) are suitable for describing the experimental behavior of mixtures with higher CV content, while the third-order (F3) and eighth-order model (F8) are more appropriate for the decomposition reaction with higher PE content. The calculation of thermodynamic parameters further show that the co-pyrolysis of CV and PE is beneficial to the decomposition process, and the mixed ratio of 3:1 is the most favorable for the reaction. Results obtained in this work are valuable for guiding research on the co-pyrolysis of biomass and plastics. • The co-pyrolysis process of CV and PE can be categorized into five distinct stages. • The activation energy of the co-pyrolysis reaction exhibited a significant decrease. • The maximum synergistic effect is achieved at a mixing ratio of 3:1. • Co-pyrolysis of CV and PE dominated Power law and Reaction order mechanism. [ABSTRACT FROM AUTHOR]

Sewage sludge (SS) and municipal solid waste incineration fly ash (MSWIFA) have characteristics of high yield, scattered distribution, and strong harm. Co-disposal of SS and MSWIFA in the existing cement kilns is a prospective way to deal with these two types of solid waste. In this study, the pyrolysis kinetic, thermogravimetric analysis, heat and mass transfer characteristics and pollutant release during SS and MSWIFA co-disposal were investigated through a series of experiments and simulations. In the experiment, pulverized coal (PC) was used as fuel to imitate the real environment of a cement kiln. According to the results, the interaction of the two solid wastes was observed mainly during the devolatilization and combustion periods. At an average blending ratio (60%) and 25 ℃/min heating rate, the blend actual mass loss rate has the largest difference compared to the linearly calculated mass loss rate (0.74%/min), with higher comprehensive combustion characteristic index (3.54), and the blends have better overall heat transfer, internally converging to 350 K. Meanwhile, when SS proportion in PC-SS-MSWIFA is between 20% and 30%, the emission concentration of SO 2 and NO was low, and it has good environmental benefits. This research aims to offer theoretical support for the co-disposal of SS and MSWIFA. [Display omitted] • Interaction of SS and MSWIFA co-disposal process are analyzed. • The interaction between mainly occurs during the devolatilization and combustion. • Blending ratio of 60 SS wt% and heating rate of 25 °C /min can better enhance the interaction. • When the MSWIFA blending ratio is larger, there is a more violent reaction in the volatile phase. • When the mixing ratio of SS in PC-SS-MSWIFA is 20%∼30%, the production of SO 2 and NO is the smallest, and the environmental benefit is the best. [ABSTRACT FROM AUTHOR]

Excavated waste in landfills contains non-negligible amounts of combustible fractions, whose mining and thermochemical treatment are promising to save land occupation and achieve energy utilization. Considering the possible changes of combustible fractions in the excavated waste during landfill time, this study comprehensively analyzed the impact of landfill time on the thermogravity characteristics, pyrolysis kinetics, products composition, and pyrolysis pathways of excavated waste using TG-FTIR-MS. The findings indicated a positive correlation between landfill time and the remaining mass resulting from pyrolysis. The activation energies for pyrolysis of excavated waste were found to be greater than those of fresh waste. Specifically, the activation energy values increased from 230.49 kJ/mol to 289.11 kJ/mol for polyethylene, from 216.38 kJ/mol to 260.91 kJ/mol for polypropylene, from 219.04 kJ/mol to 240.06 kJ/mol for expanded polystyrene, and from 210.01 kJ/mol to 279.93 kJ/mol for polyethylene terephthalate, respectively. The increment of activation energies indicates an elevated level of difficulty in the pyrolysis reaction. The pyrolysis kinetics of excavated waste were examined by the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Starink methods. It was found that FWO method showed an optimal fitting result (R2 =0.9681–0.9819), while KAS and Starink methods also showed satisfactory fitting performance. The TG-FTIR-MS results revealed that the effect of landfill time on products categories are negligible, but the change in the content of pyrolysis products is more pronounced. This study is hoped to provide fundamental insights into the thermochemical disposal and energy recovery of excavated waste in landfills. [Display omitted] • The pyrolysis of excavated combustible waste was studied by TG-FTIR-MS. • Pyrolysis residues increase with landfill time. • The activation energy of excavated waste is higher than that of fresh waste. • Pyrolysis products of excavated waste decreased with landfill time. • The results provide a basis for the thermochemical utilization of excavated waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • The primary and secondary reactions of cellulose pyrolysis are distinguished. • The effects of primary and secondary reactions on tar formation are investigated. • The contributions of major compounds on tar formation are quantified. • A new tar formation framework from cellulose to tar is established. Tar problem seriously hinders the development of biomass gasification. The tar formation of biomass is greatly influenced by cellulose. In this work, PY-GC/MS was employed for providing a precise insight into the formation of primary and secondary products, and a tar contribution index was introduced to evaluate the potential of tar formation from different origins. Combined with statistical analysis and corroboration by DFT analysis, key intermediates for tar formation are recognized, and corresponding influence is confirmed. A new framework from cellulose to tar was built. The secondary reaction acts a more important role for tar formation. The aromatic precursors and high-activity small-molecular gases are two key compounds responding to tar formation, and the existence of high-activity small-molecular gases could significantly reduce the energy barrier during tar formation. For furans, the energy barrier can be reduced from 100.2 kcal/mol to 74.2 kcal/mol in the presence of ethylene. [ABSTRACT FROM AUTHOR]

[Display omitted] • HPO 4 2− had no effect on the activation of PMS by magnetic biochar. • H 2 PO 4 − inhibited the depletion of C O, COOH, graphite N, Fe2+, and Fe0 sites. • The inhibition of SO 4 − strengthened with the increase of H 2 PO 4 − concentration. • ·OH/O 2 − contribution first elevated, then dropped with rising H 2 PO 4 − concentration. Magnetic biochar is an efficient peroxymonosulfate (PMS) catalyst with high potential for industrial applications. However, the effects of phosphate on the active sites of magnetic biochar and oxidative species remain controversial. In this study, Enteromorpha-derived magnetic biochar was prepared for the activation of PMS. Results found that C O, COOH, defects, graphite N, Fe2+, and Fe0 were the main active sites in the magnetic biochar/PMS system. The presence of monohydrogen phosphate (HPO 4 2−) had no effect on the activation of PMS. However, the existence of dihydrogen phosphate (H 2 PO 4 −) had a significant inhibitory effect and affected the production of free radicals, which was ascribed to the shielding effect of H 2 PO 4 − on graphite N, C O, COOH, Fe2+, and Fe0 active sites. Overall, this study provides insight into the main reaction mechanisms of PMS activation by magnetic biochar with co-existing phosphates, facilitating the application of magnetic biochar for practical wastewater purification in persulfate oxidation systems. [ABSTRACT FROM AUTHOR]

• H 2 production based on PLGA was modeled and validated using Aspen Plus. • CNTs is simultaneously produced in combination with the H 2 generation. • The energy conversion efficiency of the proposed processes is above 57.8%. • An impressive H 2 selectivity of 73.3% was achieved with an H conversion of 75.6%. • Detailed environmental analysis shows the CO 2 emission rate is 234.9 kg MWh−1. This simulation study presents a process based on plasma gasifiers for hydrogen (H 2) production while also producing high-value-added products carbon nanotubes (CNTs) from biomass and waste plastics. To assess the efficacy of this process, Aspen Plus V12 was employed. The accuracy of the model was confirmed through comparison with other experiments and calculations, yielding a root mean square error (RSME) of 6% and 3%, respectively. Based on this model, parameters of H 2 production are studied, and the process of energy, efficiency, and environment (3-E) are analyzed. At optimal operational parameters, such as the gasifier being 1000℃, the reformer being 800℃, the steam to feedstocks ratio (S/F) of the gasifier being 0.6, S/F of the reformer being 0.5, and plastics to biomass ratio (P/B) being 0.25, a maximum H 2 content of 73.3% could be attained. Following that, 3-E analysis shows that the energy utilization efficiency is 57.8%, the conversion efficiency of H is 75.6%, and the specific CO 2 emission rate of this system is only 234.9 kg MWh−1. Overall, the proposed model can give significant information for large-scale gasifier and H 2 production unit design, operation, commercial applications, and optimization with respect to feedstock composition. [ABSTRACT FROM AUTHOR]

Emerging contaminants can be removed effectively in heterogeneous Fenton-like systems. Currently, catalyst activity and contaminant removal mechanisms have been studied extensively in Fenton-like systems. However, a systematic summary was lacking. This review summarized: 1) The effects of various heterogeneous catalysts on emerging contaminants degradation by activating H 2 O 2 ; 2) The role of active sites in different catalysts during the activation of H 2 O 2 and their contribution to the generation of active species; 3) The modulation of degradation pathways of emerging contaminants. This paper will help scholars to advance the controlled construction of active sites in heterogeneous Fenton-like systems. Suitable heterogeneous Fenton catalysts can be selected in practical water treatment processes. [Display omitted] • The various catalysts on contaminants by activating H 2 O 2 are compared in detail. • The contribution of active sites to active species production is summarized. • The information of active species acting on emerging contaminants is discussed. • The possible research directions of active sites in H 2 O 2 -AOPs are proposed. [ABSTRACT FROM AUTHOR]

• The effect of dissolved organic matters (DOM) on organic degradation was explored. • Oxidation pathway of different DOM compounds was elucidated. • Evolution of DOM and inhibition mechanisms to pollutant degradation were revealed. • CHO-, CHON-, CHOS-, CHOP- and CHONP-based molecules showed moderate inhibition. Dissolved organic matters (DOM) are widely present in different water sources, causing significant effects on water treatment processes. Herein, the molecular transformation behavior of DOM during peroxymonosulfate (PMS) activation by biochar for organic degradation in a secondary effluent were comprehensively analyzed. Evolution of DOM was identified and inhibition mechanisms to organic degradation were elucidated. DOM underwent oxidative decarbonization (e.g., –C 2 H 2 O, −C 2 H 6 , –CH 2 and –CO 2), dehydrogenation (–2H) and dehydration reactions by ·OH and SO 4 ·−. N and S containing compounds witnessed deheteroatomisation (e.g., –NH, –NO 2 + H , –SO 2 , –SO 3 , –SH 2), hydration (+H 2 O) and N/S oxidation reactions. Among DOM, CHO-, CHON-, CHOS-, CHOP- and CHONP-containing molecules showed moderate inhibition while condensed aromatic compounds and aminosugars exhibited strong and moderate inhibition effects on contaminant degradation. The fundamental information could provide references for the rational regulation of ROS composition and DOM conversion process in a PMS system. This in turn offered theoretical guidance to minimize the interference of DOM conversion intermediates on PMS activation and degradation of target pollutants. [ABSTRACT FROM AUTHOR]

Due to the wide applications of polyurethane (PU), production is constantly increasing, accounting for 8% of produced plastics. PU has been regarded as the 6th most used polymer in the world. Improper disposal of waste PU will result in serious environmental consequences. The pyrolysis of polymers is one of the most commonly used disposal methods, but PU pyrolysis easily produces toxic and harmful nitrogen-containing substances due to its high nitrogen content. This paper reviews the decomposition pathways, kinetic characteristics, and migration of N-element by product distribution during PU pyrolysis. PU ester bonds break to produce isocyanates and alcohols or decarboxylate to produce primary amines, which are then further decomposed to MDI, MAI, and MDA. The nitrogenous products, including NH3, HCN, and benzene derivatives, are released by the breakage of C-C and C-N bonds. The N-element migration mechanism is concluded. Meanwhile, this paper reviews the removal of gaseous pollution from PU pyrolysis and discusses the removal mechanism in depth. Among the catalysts for pollutant removal, CaO has the most superior catalytic performance and can convert fuel-N to N2 by adsorption and dehydrogenation reactions. At the end of the review, new challenges for the utilization and high-quality recycling of PU are presented [Display omitted] • The factors influencing Ea of PU includes sample, model and experimental condition. • Nitrogen-containing products are produced by isocyanate cleavage and recombination. • The CaO with superior activity can convert NH 3 and HCN into N 2. • Changing raw materials and adding flame retardants will inhibit the formation of HCN. • The new challenges of PU utilization and high-quality recovery are put forward. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reutilizing ash to gasification process was feasible. • Ash played dual objective in improving gas product quality and adsorbing SO 2. • Metals in ash promoted the Dry or/and Steam reforming and Water-gas reaction. • The optimal condition of ash loading was 10 wt%. • The regenerated ash behaved a higher fertilizer potential. Due to the significant growth of the biomass gasification industry, management and disposal of ash has become one of the major environmental issues. This work proposed an innovative strategy that reutilizes ash into gasification process based on its potential catalysis to improve gas products. Reutilization of ash from corn straw (CS) air gasification in a downdraft fixed-bed gasifier was conducted for a feasibility analysis. The effect of ash loading rates (2 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%) on gasification performance were evaluated for an optimal condition analysis. Ash reutilization was proved to be feasible and able to achieve dual objective of improving gas product quality and reducing SO 2 release. Results revealed that loading ash exhibited catalysis promoting CO formation, which correlated with the metal active sites provided by the ash and led to an improvement in dry or/and steam reforming. H 2 production was also improved. These positive effects increased as ash loading rates increased, and maximum CO and H 2 content (19.97 vol% and 15.72 vol%) were achieved at the ash loading rate of 10 wt%. Accordingly, the maximum LHV of gas products (6.47 MJ/Nm3) and the minimum tar content (3.62 g/Nm3) were obtained. While excess ash (loading rate > 10 wt%) showed unsatisfactory performance, even being far behind CS gasification without ash addition. Due to containing CaO, gasification ash showed SO 2 capture capacity by forming CaSO 4. This reaction competed with the concurrent CaO carbonation, whereas the latter was the priority. The properties of by-products (regenerated ash) were evaluated for overall economic benefits, and the results indicated that it had a high fertilizer potential. These results seemed to be interesting and valuable for ash utilization and effective gasification. [ABSTRACT FROM AUTHOR]

N-methyl pyrrole (NMP) is an important nitrogenous heterocyclic compound in bio-oils produced from biomass conversion. NMP can be used as surrogate model compound to clarify the combustion chemistry of nitrogenous fuels and NO X formation mechanism. The low- to moderate-temperature oxidation experiments of NMP are carried out in atmospheric pressure jet-stirred reactor for 0.5% NMP/oxygen/Argon mixtures at different equivalence ratios (0.5, 1.0, and 2.0) over the temperature range of 760 – 1030 K. More than twenty species, including reactants, nitrogen-containing species, and oxygenated products, are measured using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). A detailed and comprehensive kinetic model for NMP oxidation is developed for the first time based on the pyrrole oxidation model developed by Pelucchi et al. and Chen et al.. Simulated results show that the present model can reasonably reproduce the experimental results. Rate of production analysis indicates that the H-abstraction reactions on the methyl group dominate in NMP oxidation at all equivalence ratios. NMP oxidation produces C4 and C5 nitrogen-containing compounds including pyridine and pyrrole. These species are found to be products of the primary reactions of NMP, and their formation pathways can be explained satisfactorily by the present model. The present work provides a basis to further understand the oxidation characteristics of nitrogen-containing heterocyclic fuels. [ABSTRACT FROM AUTHOR]

• High precision schematic energetics calculation. • Site-specific reactivity. • Revealing the competing relationship between OH-addition and H-abstraction pathways. • Providing valuable kinetic data in a wide temperature and pressure condition. Oxidation of furan-based biofuels in the atmosphere and combustion are mainly initiated by reactions with small radicals (e.g. OH radical), the kinetics of which are crucial to obtain a comprehensive understanding of combustion processes, especially in engine operation. However, the structure- and site-dependent chemistry for OH-initiated reactions of furans with oxygenated substituents is unknown. In the present study, 2-furfuryl alcohol (2FFOH) was selected as a model fuel, and a full schematic energy diagram for 2FFOH with OH was calculated by a high-level quantum chemical method (CCSD(T)/CBS//M06-2X/def2-TZVP). The temperature- and pressure-dependent behavior of the rate coefficients k (T , P) for 2FFOH with OH was calculated at 298–2500 K and 0.01–10 atm by using the Rice–Ramsperger–Kassel–Marcus/Master equation method. Our calculations reveal that the rate coefficients of H-abstraction from the side chain are faster than those from the ring at T ≤ 2300 K. The observed temperature dependence behaviors of the total rate coefficients are consistent with prior experimental studies of other furans (e.g., furan, 25DMF and 2MF) with OH. The total rate coefficients of 2FFOH with OH exhibit a slightly positive pressure dependence only in the temperature range of 500–1000 K. We also found that the OH-addition pathways for 2FFOH with OH system dominate at T ≤ 1300 K. Moreover, the thermodynamic and kinetic data determined in the present work would be valuable for the future development of the fundamental chemical reaction mechanism of furan-based fuels in the atmosphere and combustion. [ABSTRACT FROM AUTHOR]

The rate constants for H-initiated reactions of 2-furfuryl alcohol (2FFOH) were calculated for the first time by a high-level quantum chemical method combined with the Rice–Ramsperger–Kassel–Marcus (RRKM) theory/Master equation method. A detailed potential energy surface was constructed by the CCSD(T)/CBS//M06–2X/def2-TZVP method, involving H-abstraction, initial H-addition, adduct-subsequent pathways and interconnected conversion pathways. The H-addition reaction on the β -carbon and δ -carbon sites to form bimolecular products 2-methylene-2,3-dihydrofuran plus OH and 2-methylene-2,5-dihydrofuran plus OH were found to be the major product channels at high temperatures. No significant pressure dependence is observed for the total rate constants of 2FFOH + H. However, the overall kinetics behavior does not reflect the site characteristics, i.e., the site-specific rate constants for each reaction channel show different temperature and pressure dependences. The total rate constants via the H-addition mechanism are higher by factors of 3.3–10 than those via H-abstraction channels under all studied conditions. The present updated kinetic model obtained by applying these new calculated rate constants can better predict 2FFOH decomposition, especially at 30 Torr, and it can also lead to good predictions of the speciation profiles (e.g., vinyl ketene) during 2FFOH pyrolysis. The data calculated in the present work can provide valuable information for the development of combustion models of furan-based biofuels. [ABSTRACT FROM AUTHOR]

[Display omitted] • A zero-waste biorefinery concept was developed by pyrolyzing the residual microalgae biomass. • The pyrolysis process was effectively modeled using an integrated ANN and RSM technique. • The maximum H 2 production of 44.46 vol% was produced at optimal conditions. • At 500 °C, max. hydrocarbons and min. N- & O-containing compounds observed in bio-oil. • With the increasing temperature, the biochar exhibited more cracks and holes. The present work focused on the pyrolysis-based valorization of microalgae biomass residual for the generation of sustainable fuel and value-added chemicals. Key pyrolysis factors, including temperature, residence time, particle size, and heating rate, were modeled via an artificial neural network (ANN) and response surface methodology (RSM) models. The use of such an integrated technique was able to conquer the individual constraints of both modeling approaches. RSM model for H 2 -rich syngas demonstrated that the value; R2 = 0.99, minimum p = 0.00, and maximum F = 3877.16 has close relation among the statistical parameters. The ANN model for H 2 -rich syngas revealed that higher R2 = 0.9985 and lower RSME = 0.1038 were obtained for the training phase, while; the higher R2 and lower RSME values of 0.9862 and 0.2661 were estimated for the training phase hence showed a better agreement among the parameters. Optimum H 2 production of 44.46 vol% was produced at temperature = 516.76 °C, residence time = 17.7 min, particle size = 0.23 mm, and heating rate = 17.37 °C/min. All the pyrolytic products have been characterized in detail and are recommended for high end-use. The GC/MS technique revealed that bio-oil was constituted of various organic complexes, which could be used as a substitute for hydrocarbon fuels after undergoing certain upgradation procedures (e.g., hydrotreating, hydrodeoxygenation, hydrodenitrogenation, and hydrocracking) and extracted into different chemicals. In addition, the biochar was characterized using the SEM technique, which also demonstrated its potential as fuel and in a variety of other applications. The study showed that de-fatted Chlorella sorokiniana residue (De-CR) could be efficiently employed to produce bio-energy precursors. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fast characterization method for biodiesel using ATR-FTIR and ML was proposed. • The optimal accuracy of the characterization method could reach as high as 100%. • Data downscaling improved the correlation of the biodiesel model to approx. 0.92. • PC4 and PC5 in the data downscaling had the highest weight in the biodiesel model. • This study is promising for the development of the biodiesel production industry. This study proposed a fast characterization method for biodiesel based on attenuated total reflection flourier-transform infrared spectroscopy and machine learning models. The concerning characteristics of biodiesel include unsaturated group content, O content, and contents of four representative esters. A total of 71 biodiesel samples were produced from a lab-scale reactor. Their spectral data and characteristics were collected and used as training data for machine learning models. The established model framework consisted of two data compression sections, a classification section, and a regression section, all of which use machine learning models, such as principal component analysis, support vector machine, artificial neural network, and random forest. The accuracy, correlation, and sensitivity of the proposed method were evaluated and optimized. Furthermore, the interpretation of the models was discussed. The results showed that the principal component analysis model was a satisfactory preprocessing procedure for the downstream classification and regression models. Under the optimal model parameters, the integrated framework could reach an average accuracy rate of 93.18% and a Pearson correlation coefficient of 0.92. Principal component number 4 and 5 showed the highest sensitivity towards the predicting results, implying that their highly weighted wavenumber ranges and the correlated functional groups played the most important role in the predicting process. The findings of this study could lead to a simple and efficient approach for characterizing the properties of biodiesel, which in turn could promote the development of similar biomass-derived liquid fuels. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pt-decorated shrimp shell biochar was applied as cathode catalyst. • The Pt/SSB catalysts achieved efficient and selective conversion of phenol. • The C C and C O bonds in precursor were reduced by [H] to produce cyclohexanol. • The C O, Pt, and Pt-N x sites dominated in phenol conversion. The development of highly-active electrocatalysts and identification of active sites contribution are necessary for electrocatalytic hydrogenation (ECH) of bio-oil. Herein, the Pt-decorated shrimp shell biochar (SSB) catalysts with high nitrogen content was prepared successfully. The biochar-based catalysts were first used for the ECH of bio-oil model compounds. Results showed that the Pt/SSB catalysts exhibited excellent electrocatalytic activity and stability, realizing 100 % conversion of phenol and 98 % total selectivity of cyclohexanone and cyclohexanol within 5 h. By correlation analysis and density functional theory (DFT) calculations, the Pt, Pt-N x , and C O sites in Pt/SSB catalysts were found to play an important role in the stepwise hydrogenation of phenol. Furthermore, the Pt-N x sites were identified as the main contributor to the high selectivity of cyclohexanol generation. This study lays the foundation for the controllable preparation of electrocatalysts with high activity and stability, which is significant for large-scale upgrading of bio-oil in the future. [ABSTRACT FROM AUTHOR]

Biochar (e.g. pyrochar and hydrochar) is considered a promising adsorbent for Cd removal from aqueous solution. Considering the vastly different physicochemical properties between pyrochar and hydrochar, the Cd2+ sorption capacity and mechanisms of pyrochars and hydrochars should be comparatively determined to guide the production and application of biochar. In this study, the hydrochars and pyrochars were prepared from Napier grass by hydrothermal carbonization (200 and 240 °C) and pyrolysis (300 and 500 °C), respectively, and the physicochemical properties and Cd2+ sorption performances of biochars were systematically determined. The pyrochars had higher pH and ash content as well as better stability, while the hydrochars showed more oxygen-containing functional groups (OFGs) and greater energy density. The pseudo second order kinetic model best fitted the Cd2+ sorption kinetics data of biochars, and the isotherm data of pyrochar and hydrochar were well described by Langmuir and Freundlich models, respectively. In comparison with hydrochar, the pyrochar exhibited better Cd2+ sorption capacity (up to 71.47 mg/g). With increasing production temperature, the Cd2+ sorption capacity of pyrochar elevated, while the reduction was found for hydrochar. The mineral interaction, complexation with surface OFGs, and coordination with π electron were considered the main mechanisms of Cd2+ removal by biochars. The minerals interaction and the complexation with OFGs was the dominant mechanism of Cd2+ removal by pyrochars and hydrochars, respectively. Therefore, the preparation technique and temperature have significant impacts on the sorption capacity and mechanisms of biochar, and pyrochar has better potential for Cd2+ removal than the congenetic hydrochar. [Display omitted] • Cd2+ sorption capacity of biochar was affected by production technique and temperature. • Pyrochar exhibited greater Cd2+ adsorption capacity than hydrochar. • The interaction with minerals dominated the Cd2+ adsorption on pyrochars. • Complexation with OFGs was the main mechanism of Cd2+ adsorption on hydrochars. [ABSTRACT FROM AUTHOR]

[Display omitted] • TAP can remove organic pollutants from wastewater effectively. • Direct, microwave and photo heating are major heating types for PS activation. • SO 4 •− and •OH are main ROS in TAP systems. • The synergistic activation of PS by catalysts and heat facilitates decontamination. • Most anions and DOM inhibit TAP oxidation, while catalysts usually promote it. Thermal activation of persulfates (TAP) is a facile and easy-to-operate advanced oxidation technology for on-site decontamination of organic pollutants. Sulfate (SO 4 •−) and hydroxyl radicals (•OH) are the typical reactive oxygen species (ROS) in the processes of TAP. To date, numerous TAP systems have been developed to degrade recalcitrant contaminants in water. However, a comprehensive analysis of different thermal activation modes, particularly mechanisms and controlled generation of ROS, has not yet been reported. In this work, we present an overall review on different TAP systems. Specifically, diverse heating approaches such as thermal heating, microwave-induced heating and photothermal heating have different features in TAP and generate varying performances. Microwave heating for persulfate activation usually performs better than thermal heating at the same temperature, due to the intensified generation of radicals and boosted oxidation kinetics. Photothermal heating is cost-effective and eco-friendly via using sustainable solar energy. Moreover, the most appealing aspect of TAP is the promise of leveraging industrial waste heat to establish upscale integrated systems. Solution pH and background factors (e.g. , anions and dissolved organic matters) have complicated impacts because of radical scavenging and the production of less reactive or reductive species. In addition, the presence of homogeneous and heterogeneous catalysts can enhance the activity of TAP systems at low temperature, while the synergistic contribution of catalytic oxidation will be less significant at high reaction temperature. Finally, conclusions and challenges of TAP systems in actual water remediation are presented. [ABSTRACT FROM AUTHOR]

Sorption is considered a cost-effective technique for cadmium (Cd) removal from water, while the exhausted Cd-enriched sorbent should be properly disposed of. In this study, pyrolysis of exhausted hydrochar sorbent was conducted at 300–900 °C, and the behavior of Cd and the physicochemical properties and environmental applications of the regenerated biochar were investigated. The vaporization of adsorbed Cd in hydrochar was greatly enhanced by elevating pyrolysis temperature, and almost no Cd was observed in the regenerated biochars obtained at 700–900 °C. In comparison with the raw hydrochar, the regenerated biochars showed higher pH, ash content, and carbon content, while the contents of hydrogen and oxygen decreased. According to the toxicity characteristic leaching procedure result, the toxicity and mobility of Cd in hydrochar were greatly reduced after pyrolysis. Notably, the regenerated biochar showed much higher Cd sorption capacity (26.05–30.24 mg/g) than the raw hydrochar (6.70 mg/g). Surface complexation with oxygen-containing functional groups was the dominant Cd sorption mechanism for hydrochar, and precipitation between Cd2+ and carbonates dominated the Cd removal by the regenerated biochars. These results illuminated that pyrolysis can be an effective technique for the harmless disposal of exhausted hydrochar sorbent and the regeneration of valuable biochar. [Display omitted] • Vaporization of Cd in hydrochar was enhanced by elevating pyrolysis temperature. • The regenerated biochars showed different properties compared with hydrochar. • The toxicity and mobility of Cd in hydrochar were greatly reduced after pyrolysis. • The regenerated biochar showed much higher Cd sorption capacity than hydrochar. • Different mechanisms dominated the Cd sorption by hydrochar and biochar. [ABSTRACT FROM AUTHOR]

[Display omitted] • CLGOU of biogas residue was investigated on Mn-doped Ca 2 Fe 2 O 5 oxygen carrier. • Oxygen uncoupling capability was observed on Mn-doped Ca 2 Fe 2 O 5. • The doped Mn led to the conversion of lattice oxygen to active oxygen. • The cold gas efficiency and carbon conversion efficiency for MCF were 13.37% and 17.22% higher than CF. • The results proved the potential of CLGOU as an effective method to treat biogas residue. Anaerobic digestion is an important approach to treat and utilize kitchen waste, while kitchen waste derived biogas residue (BR) disposal remains a serious problem in this process. This study investigated the feasibility of chemical looping gasification (CLG) as an efficient way to treat and generate syngas from BR. Besides, Mn-doped Ca 2 Fe 2 O 5 (MCF) as a novel oxygen carrier with mild oxygen uncoupling capability was developed, and its performance against traditional Ca 2 Fe 2 O 5 (CF) oxygen carrier was compared. Results indicated that, significant oxygen release capability was observed on the prepared MCF oxygen carrier. In the gasification tests, CLG with MCF at 800 ℃ showed optimal total gas yield, carbon conversion, and cold gas efficiency, which increased 0.08 Nm3/kg, 17.22%, and 13.37% compared to CF, respectively. According to the XPS, H 2 -TPR and XRD characterization results, the optimal performance of MCF could be attributed to the oxygen uncoupling characteristic brought by Mn addition. The formation of the oxygen uncoupling capability of MCF could be explained by three reasons: (1) Mn in MCF mainly existed in form of Mn3+ and Mn4+, which resulted in the extremely strong oxidability at a temperature as low as 250 ℃. (2) The higher Fe3+/Fe2+ ratio of 1.55 in MCF than CF caused by Mn addition led to greater oxidability of Fe ions. (3) MCF had a higher lattice oxygen amount than CF at about 3.86%, and the lattice oxygen in its crystal structure had been transformed into active lattice oxygen species, which were between lattice oxygen (O2–) and atomic adsorbed oxygen (O−). As a result, this paper investigated the potential of CLG to treat and utilized BR, and the superiority of CLG with oxygen uncoupling (CLGOU) on MCF was highlighted. It's hoped that this study could provide a fundamental knowledge on CLG and CLGOU of BR, and benefit to better downstream process design of anaerobic digestion industry. [ABSTRACT FROM AUTHOR]

2-Furfuryl alcohol, derived from non-edible biomass, is the significant component of bio-oil in the pyrolysis of lignocellulose biomass and a potential alternative fuel or fuel additive. To better optimize the pyrolysis model of lignocellulose to improve the properties of pyrolysis bio-oil and further understand the combustion characteristics of 2-furfuryl alcohol, the pyrolysis experiments were performed in a flow reactor at 30 Torr for T = 1006 – 1339 K and 760 Torr for T = 850 – 1131 K, and in a jet-stirred reactor at 760 Torr for T = 750 – 1050 K. The pyrolysis products, including radicals (methyl, propargyl, allyl, and cyclopentadienyl), isomers (furfural/2-ethyl furan, furan/vinyl ketene, and allene/propyne), and aromatics (benzene, toluene, indene, etc.) were identified and measured using synchrotron vacuum ultraviolet photoionization mass spectrometry. A comprehensive kinetic model for 2-furfuryl alcohol pyrolysis was developed and was validated against the experimental data in the present and previous work. Rate of production analysis indicated that the C–O bond dissociation reaction, H-abstraction reactions on the hydroxymethyl group, and the H-addition reactions on the furan-ring controlled the consumption of 2-furfuryl alcohol and the formation of primary pyrolysis products like 2-methyl furan, 2-ethyl furan, furfural, and furan. In addition, the OH-addition reaction on the furan-ring had a certain contribution to the consumption of 2-furfuryl alcohol, while the contribution of H-shift reactions was negligible. The present work systematically compared the effects of methyl, ethyl, and hydroxymethyl groups on the decomposition of furanic fuels and the formation of major products. The results showed that the substituent groups can reduce the decomposition temperature of the fuels, especially the ethyl and hydroxymethyl groups. The alkyl substituent group can promote the formation of small hydrocarbons, of which the mole fraction increased with the length of the carbon chain increasing. The hydroxymethyl group facilitated the formation of oxygenated products. [ABSTRACT FROM AUTHOR]

• Effect of torrefaction temperature on the combustion characteristics of lignite was studied. • Torrefaction significantly improves combustion performance of lignite with a higher reactivity. • The optimum torrefaction temperature for lignite upgrading was determined as 200 °C. • Kinetic analysis indicates that torrefaction had no significant effects on activation energies. Torrefaction treatment is a promising method for lignite upgrading. However, its effect on the combustion characteristics has not been fully evaluated. In this study, the combustion characteristics of lignite and its upgrading samples by torrefaction were studied via non-isothermal thermogravimetric analysis. Results show that increasing the torrefication temperature decreases the volatile content while increasing the fixed-carbon in the fuels. The mole ratios of both H/C and O/C in the samples decreases as the torrefaction temperature increases. Torrefaction treatment significantly improves the combustion performance of lignite with a higher reactivity index S , and the optimum torrefaction temperature was determined to be 200 °C. The upgrading lignite by torrefaction at 200 °C has the lowest temperatures of T f and T p as well as the maximum corresponding DTG value. Furthermore, the results of three-parallel-DAEM model analysis results show that the activation energies corresponding to the three peaks are 176.1 kJ/mol, 186.5 kJ/mol and 221.7 kJ/mol, respectively, and that increasing torrefaction temperature had no significant effects on activation energies. With the torrefaction temperature increasing, the first standard deviation decreased while the third standard deviation increased. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is one of the most common 3D printing materials. However, once processed, the properties of its raw material are altered. 3D printed PLA waste (3DP-PLAW) has a relatively high calorific value with low impurities, which makes waste-to-energy utilization effective through thermal conversion. In this study, the pyrolysis characteristics of 3DP-PLAW were investigated using thermogravimetric–Fourier infrared spectroscopy/gas chromatography−mass spectrometry (TG-FTIR/GC-MS). Two main pyrolysis stages were observed at 260–390 ℃ and 390–500 ℃ during 3DP-PLAW pyrolysis, which contradicts with findings from previous research. Upon reaching 390 °C, residual ash and char triggered a secondary reaction. It is speculated that the occurrence of a second pyrolysis stage is attributed to changes in the physicochemical properties of the PLA during the 3D printing process. It was also found that 3DP-PLAW had a higher heating value (HHV) (20.949 MJ·kg−1) than that of the raw PLA. The pyrolysis kinetics of 3DP-PLAW was analyzed using the distributed activation energy model (DAEM) as well as Flynn-Wall and Ozawa (FWO), Starink, and Friedman methods; it was found that the activation energies obtained from these methods were similar (approximately 206 kJ·mol−1). Therefore, these methods are suitable for biomass plastics. The TG-FTIR/GC-MS results showed that CO, CO 2 , CH 4 , CH 3 CHO, esters, carbon-based compounds, and ethene were the main gaseous products of 3DP-PLAW pyrolysis. In contrast to a previous study on raw PLA, no ketone was detected in the gaseous products during 3DP-PLAW. These findings allow for the production of energy products, instead of the usage of natural gas for recycling, which underlines the potential value of 3DP-PLAW for energy recovery and subsequent improvements on the current 3DP-PLAW disposal methods. [Display omitted] • Pyrolysis of 3DP-PLAW as an emerging solid waste was studied via TG-FTIR/GC-MS. • 3DP-PLAW mainly decomposed in temperature stages of 260–390 ℃ and 390–500 ℃. • Activation energy of 206 kJ/mol was obtained via 4 pyrolysis kinetic methods. • Pyrolysis products distribution of 3DP-PLAW towards energy recovery was studied. • The results provide fundamentals for thermochemical utilization of 3DP-PLAW. [ABSTRACT FROM AUTHOR]

Defect type and interactions among active sites are critical in heterogeneous peroxymonosulfate (PMS) system. Herein, a continuous flow fixed bed PMS reactor with distilled spirits lees derived biochar (DSLBs)/quartz wool was designed to explore the synergistic roles of active sites. Satisfyingly, with high graphite N, C O content and defect degree, DSLB-800 exhibited superior catalytic activity, durability and applicability for sulfamethoxazole (SMX) removal. The dominant contribution of 1O 2 , and minor roles of SO 4 •− and •OH were confirmed. Single graphite N, C O and C-O, combined interactions between graphite N and pyridine N, graphite N and pyrrole N, pyridine N and pyrrole N, C O and O C-O, O C-O and C-O, as well as interactions among graphite N, pyridine N and pyrrole N contributed to 1O 2 generation. Notably, the double vacancy defect was also a preferential site for 1O 2 production. This study advances mechanistic understanding of collaborative contribution of active sites to PMS activation. [Display omitted] • Distilled spirits lees derived biochar (DSLB) was prepared with adjustable sites. • DSLBs showed high activity in a continuous flow fixed bed PMS reactor. • Synergistic contribution of different sites to PMS activation was revealed. • Double vacancy defect was identified as a preferential site for 1O2 production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Active site on sewage sludge-derived biochar was fine-tuned by regulated pyrolysis. • Single SO 4 •−, •OH with SO 4 •− or 1O 2 contributed to ciprofloxacin removal. • Each contribution site for reactive species generation was identified. • The synergy of Fe, N and O sites for oxidative species production was established. Active sites on the surface of heterogeneous catalysts accounted for the generation of reactive oxygen species (ROS) from peroxymonosulfate (PMS) toward organic degradation. In this study, the surface chemistry of sewage sludge-derived biochar (SSB) was regulated by controlled pyrolysis and SSB was used for PMS activation and oxidation of antibiotic ciprofloxacin (CIP). SSB-20–120 achieved high CIP removal efficiencies in both batch test (94.2%) and continuous column test (96.3%) with PMS. The species and contents of Fe, N and O as active sites on SSB and their relationships with generated ROS (SO 4 •−, •OH, and 1O 2) for CIP degradation were comprehensively identified. Fe(0), –OH, C = O and the pairwise interaction among Fe(0), Fe(II) and Fe(III) were responsible for SO 4 •− generation. Besides, pyrrolic N, graphitic N and the co-effect among pyridinic N, pyrrolic N and graphitic N exerted positive effects on •OH and SO 4 •− generation simultaneously. Meanwhile, Fe(II), Fe(III), pyrrolic N, graphitic N, lattice O with –OH, lattice O with C = O, the interactions among Fe(0), Fe(II) and Fe(III) as well as pyridinic N, pyrrolic N and graphitic N contributed to the production of •OH coupling with 1O 2. Moreover, SO 4 •− and 1O 2 , as well as the co-effects of •OH with SO 4 •− and •OH with 1O 2 were in favor of CIP degradation. This research provided new insights into the biochar synthesis, structure evolution, and the generation mechanism of reactive oxygen species from PMS activation. Outcomes are beneficial to sewage sludge utilization and developing low-cost catalysts for wastewater remediation. [ABSTRACT FROM AUTHOR]

Biomass fuel, as a kind of alternative fuel, offers the possibility of a higher sustainability of the energy system. Furanic fuels that are proposed as next-generation biomass-derived fuels have become one of the targets of recent researches. Here the studies on the low-temperature oxidation of 2-ethylfuran (EF2) in a jet-stirred reactor were performed at atmospheric pressure, at temperature range of 600–900 K and at three equivalence ratios of 0.5, 1.0 and 2.0, respectively. Over 20 oxidation products were detected and measured by using synchrotron vacuum ultraviolet photoionization mass spectrometry, including hydrocarbons, such as methane, ethylene, acetylene, et al., and oxygenated species, such as formaldehyde, ketene, acetaldehyde, 2-methylfuran and 2-vinylfuran, especially the isomers (furan/vinyl ketene) et al. A detailed low-temperature oxidation kinetic model with 723 species and 3300 reactions based on the reported models and theoretical calculations was developed to demonstrate the experimental results in this work. Rate of production analysis shows that, in the low-temperature oxidation of EF2, the consumption of EF2 is dominated by hydrogen atom-abstraction to produce 1-(2-furyl)ethyl radical and by hydroxyl radical-addition onto C(2) of EF2 to produce 2,3-dihydro-2-hyroxyl-2-ethyl-3-furanyl radical at 50% EF2 consumption. The subsequent dominant consumption pathway of 1-(2-furyl)ethyl radical reacting with hydroperoxyl radical will generate 1-(2-furyl)ethyloxyl radical or 2,5-dihydro-5-ethyliden-2-furanyloxyl radical, while 2,3-dihydro-2-hyroxyl-2-ethyl-3-furanyl radical will subsequently go through β -scission to produce carbon monoxide + acetylene + formyl radical eventually. Sensitivity analysis indicates that reactions related to these four radicals, i.e., hydroxyl, 1-(2-furyl)ethyl, 2,5-dihydro-5-ethyliden-2-furanyloxyl and 2,3-dihydro-2-hyroxyl-2-ethyl-3-furanyl, are critical in the consumption of EF2. Hydroxyl radical is mainly produced by the decomposition of hydroperoxide at the equivalence ratio of 0.5 and 1.0, while at the equivalence ratio of 2.0, reactions between 1-(2-furyl)ethyl radical and hydroperoxyl radical, as well as that between methyl radical and hydroperoxyl radical, become more important. [ABSTRACT FROM AUTHOR]

Duckweed easily growing in wastewater and absorbing a large amount of nitrogen and phosphorus from wastewater is now being considered as a promising solution to treat eutrophic water. However, if it is not salvaged in time, its rapid accumulation will cause secondary pollution to the water body. Duckweed is rich in protein and starch, but the content of lignin is rather low, making it an ideal biomass feedstock for energy production. This work reviews the detailed steps for producing bio-oil, bio-ethanol, biogas and other kinds of bioenergy from duckweed through hydrothermal liquefaction, pyrolysis, anaerobic digestion and fermentation processes. The reaction pathways of duckweed to produce bio-oil and bioethanol are introduced in detail. Opportunities and challenges of each conversion technology are thereafter discussed. The viability of producing biofuels and industrial precursors in a sustainable mode is also assessed. According to the characteristics of different kinds of duckweed, appropriate utilization methods should be applied to produce bioenergy to realize environmental, economic and energy benefits. [Display omitted] • Rapid growth and biochemical composition make duckweed a promising energy resource. • Bioenergy production from duckweed coping with energy shortage and water eutrophication simultaneously. • Biochemical composition of duckweed is a decisive factor of subsequent utilization and derived products. • The prospects of duckweed in high value-added industrial precursors production are encouraging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic ozonation of various Cl-VOCs exhibited different performances. • Synergistic/inhibited effects co-existed in catalytic ozonation of mixed Cl-VOCs. • Degradation difficulty and competitive adsorption jointly determined the priority. • H 2 O introduction exhibited negligible impact for Cl-VOCs catalytic co-ozonation. This paper investigated catalytic ozonation of different Cl-VOCs (chlorobenzene (CB), dichloroethane (DCE), dichloromethane (DCM) and trichloroethylene (TCE)) over series of supported MnO x catalysts. These Cl-VOCs with different molecule structures exhibited obviously difference in catalytic performances and byproducts formation. Interestingly, the correlation between catalytic behaviors and surface properties of catalysts was inconsistent for different Cl-VOCs. In comparison, Mn/HZSM-5(27) presented a better conversion and mineralization rate (MAR) for most of Cl-VOCs due to its abundant surface acidity and excellent pore structures. Catalytic co-ozonation of mixed Cl-VOCs over Mn/HZSM-5(27) showed co-existence of inhibitive and promotive effects. For instance, CB conversion occupied priority compared with DCE and TCE, and MAR was enhanced in the mixture. Thereafter, the temperature programmed desorption results of mixed Cl-VOCs proved competitive adsorption between molecules. Both competitive adsorption and difficulty of Cl-VOCs degradation were the determining factors in catalytic co-ozonation of Cl-VOCs. Besides, catalytic co-ozonation of Cl-VOCs with presence of H 2 O exhibited negligible impact. These observations provide valuable reference for industrial application with co-presence of multiple Cl-VOCs and water vapor. [ABSTRACT FROM AUTHOR]

The harmless treatment of heavy metal-enriched hyperaccumulator biomass is the main barrier to the industrialization of phytoremediation. Hydrothermal conversion of Sedum alfredii using different solvents (i.e ·H 2 O and HCl) at 210–300 ℃ was performed to investigate the behaviors of Cd and Zn, and the characteristics and potential application of the derived hydrochars were determined. Low temperature and HCl addition favored the removal of Cd/Zn from the solid phase. The highest removal efficiencies of Cd (95.0%) and Zn (89.3%) were achieved at 210 ℃ with the presence of HCl. The yield, pH, ash content, element concentration, functional groups, and crystalline minerals of the derived hydrochar were influenced by the reaction temperature and addition of HCl. The leaching risk of Cd and Zn was significantly reduced by hydrothermal conversion. The addition of HCl facilitated the immobilization of Zn, while it enhanced the mobility of Cd. Moreover, the hydrochar derived at 210 ℃ showed increased sorption capacity towards Cu, and the addition of HCl greatly improved the energy density of hydrochar. These results suggest that HCl-mediated hydrothermal conversion could be a promising technique to achieve the separation of Cd and Zn from hyperaccumulator biomass as well as the production of value-added hydrochar. [Display omitted] • Hydrothermal conversion of S. alfredii in water- and acid-medium was performed. • Low temperature and acid medium favored the removal of Cd/Zn from hydrochar. • The leachable contents of Zn and Cd in hydrochar decreased with addition of HCl. • Cu sorption capacity of hydrochar was reduced after modification with HCl. [ABSTRACT FROM AUTHOR]