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Low-cost and green preparation of efficient sorbents is critical to the removal of organic contaminants during water treatment. In this study, the co-pyrolysis of macroalgae and oyster shell was designed to synthesize nitrogen-doped porous biochars for sorption removal of atrazine from water. Oyster shell played a significant role in opening pores in macroalgae-derived biochars, resulting in the surface area of the macroalgae (Enteromorpha prolifera and Ulva lactuca) and oyster shell co-pyrolyzed carbonaceous as high as 1501.80 m2 g−1 and 1067.18 m2 g−1, the pore volume reached 1.04 cm3 g−1 and 0.93 cm3 g−1, and O/C decreased to 0.09 and 0.08, respectively. The sorption capacity of atrazine to nitrogen-doped porous biochars (the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous) reached 312.06 mg g−1 and 340.52 mg g−1. Pore-filling, hydrogen bonding, π-π or p-π stacking and electrostatic interaction dominated the multilayer sorption process. Moreover, the nitrogen-doped porous biochars showed great performance in cyclic reusability, and the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous sorption capacity still reached 246.13 mg g−1 and 255.97 mg g−1, respectively. Thus, this study suggested that it is feasible and efficient to remove organic contaminants with the nitrogen-doped porous biochars co-pyrolyzed from macroalgae and oyster shell, providing a potential green resource utilization of aquatic wastes for environmental remediation. Highlights: Nitrogen-doped porous biochars (NPBs) were derived from natural wastes. Oyster shell enhanced the micropore and mesopore structures of NPBs. Physical sorption dominated atrazine sorption onto the NPBs. [ABSTRACT FROM AUTHOR]

In this study, the co-pyrolysis of sewage sludge (SS), two-component special municipal waste (SMW) and plastic waste (Plastic) was studied using thermogravimetric equipment and a scaled-up tubular reactor. During the experiments, the effects of the raw material composition and pyrolysis temperature on the decomposition processes, the product yields and compositions were investigated. It was found that co-pyrolysis was a series of complex reactions and resulted in more volatile and lower residue yield than the pyrolysis of the individual raw materials. In some cases (e.g., 25%SMW + 75%Plastic, 25%SS + 75%Plastic, 50%SS + 50%Plastic blends), it also caused a higher synthesis gas yield and H2/CO ratio. During the thermogravimetric analysis, the beneficial effects occurred at lower temperatures, but in the scaled-up experiments, these effects only prevailed at 900 °C as a result of the larger amount of raw materials and the worse heat transfer. The produced gases can be characterized by a lower heating value of 17.3–35 MJ/Nm3. Therefore, they can be used for energetic purposes; however, before chemical use, further quality improvement is needed due to the lower H2/CO ratios. [ABSTRACT FROM AUTHOR]

The disposal of municipal sewage sludge (MSS) from wastewater treatment plants poses a major environmental challenge due to the presence of inorganic and organic pollutants. Co-pyrolysis, in which MSS is thermally decomposed in combination with biomass feedstocks, has proven to be a promising method to immobilize inorganic pollutants, reduce the content of organic pollutants, reduce the toxicity of biochar and improve biochar's physical and chemical properties. This part of the review systematically examines the effects of various co-substrates on the physical and chemical properties of MSS biochar. This review also addresses the effects of the pyrolysis conditions (temperature and mixing ratio) on the content and stability of the emerging pollutants in biochar. Finally, this review summarizes the results of recent studies to provide an overview of the current status of the application of MSS biochar from pyrolysis and co-pyrolysis for the remediation of HM-contaminated soils. This includes consideration of the soil and heavy metal types, experimental conditions, and the efficiency of HM immobilization. This review provides a comprehensive analysis of the potential of MSS biochar for environmental sustainability and offers insights into future research directions for optimizing biochar applications in soil remediation. [ABSTRACT FROM AUTHOR]

Co-pyrolysis technology is considered to be one of the most promising methods for the sustainable utilization of biomass wastes, as it can realize waste reduction and convert wastes into high-value-added products with little impact on the environment. The evaluation of thermal characteristics and product properties is necessary for understanding this technique. In this paper, thermal characteristics and kinetic and thermodynamic analysis during the co-pyrolysis of mushroom residue (MR) with pine sawdust (PS) or wheat straw (WS) were investigated in a TGA. The carbon structure and surface textures of co-pyrolytic char were explored using Raman spectroscopy and a scanning electron microscope. As the PS or WS mass ratio increased, the devolatilization index increased obviously, indicating that volatile release was promoted and concentrated. Weak interactions were observed between 250 and 400 °C during the co-pyrolysis process, which primarily affected the mass transfer, resulting in a change in the thermal decomposition temperatures and rates. The interactions had no prominent influence on the volatiles' yields. The non-additive performance of average activation energies for the blends was observed due to the interactions, and the lowest average activation energy was obtained when the PS or WS mass ratio was 50%. The lower average pre-exponential factor of the blends indicated the reduced complicacy of the pyrolysis reaction. The relatively small deviation between the activation energy and enthalpy change (4.94–5.18 kJ·mol−1) signified the energy sensitivity of product formation. PS promoted the formation of small aromatic rings (<6 fused rings) in co-pyrolytic chars, whereas WS favored the production of larger rings (≥6 fused rings). The surface textures of the co-pyrolytic chars became porous, and the greater fractal dimensions of the surface morphology for the co-pyrolytic chars indicated that the char surface became irregular and rough. [ABSTRACT FROM AUTHOR]

Pyrolytic synergistic interactions, in which the production of pyrolyzates is enhanced or inhibited, commonly occur during the co-pyrolysis of different polymeric materials, such as plastics and biomass. Although these interactions can increase the yield of desired pyrolysis products under controlled degradation conditions, the desired compounds must be separated from complex pyrolyzates and further purified. To balance these dual effects, this study was aimed at examining pyrolytic synergistic interactions during slow heating co-pyrolysis of biodegradable plastics including polylactic acid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexaoate) (PHBH) and petroleum-based plastics including high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). Comprehensive investigations based on thermogravimetric analysis, pyrolysis–gas chromatography/mass spectrometry, and evolved gas analysis-mass spectrometry revealed that PLA and PHBH decompose at lower temperatures (273–378 °C) than HDPE, PP, and PS (386–499 °C), with each polymer undergoing independent decomposition without any pyrolytic interactions. Thus, the independent pyrolysis of biodegradable plastics, such as PLA and PHBH, with common plastics, such as HDPE, PP, and PS, can theoretically be realized through temperature control, enabling the selective recovery of their pyrolyzates in different temperature ranges. Thus, pyrolytic approaches can facilitate the treatment of mixed biodegradable and common plastics. [ABSTRACT FROM AUTHOR]

With the increasing production of municipal sewage sludge (MSS) worldwide, the development of efficient and sustainable strategies for its management is crucial. Pyrolysis of MSS offers several benefits, including volume reduction, pathogen elimination, and energy recovery through the production of biochar, syngas, and bio-oil. However, the process can be limited by the composition of the MSS, which can affect the quality of the biochar. Co-pyrolysis has emerged as a promising solution for the sustainable management of MSS, reducing the toxicity of biochar and improving its physical and chemical properties to expand its potential applications. This review discusses the status of MSS as a feedstock for biochar production. It describes the types and properties of various co-substrates grouped according to European biochar certification requirements, including those from forestry and wood processing, agriculture, food processing residues, recycling, anaerobic digestion, and other sources. In addition, the review addresses the optimization of co-pyrolysis conditions, including the type of furnace, mixing ratio of MSS and co-substrate, co-pyrolysis temperature, residence time, heating rate, type of inert gas, and flow rate. This overview shows the potential of different biomass types for the upgrading of MSS biochar and provides a basis for research into new co-substrates. This approach not only mitigates the environmental impact of MSS but also contributes to the wider goal of achieving a circular economy in MSS management. [ABSTRACT FROM AUTHOR]

Sewage sludge has long been perceived as the bottleneck of wastewater treatment plants in China, restraining the healthy development of sewage treatment for decades. In recent years, pyrolysis as a promising multifunctional platform has attracted increasing interest for converting sludge into valuable resources. However, the generation and presence of pyrolysis tar, one of the key by-products during sludge pyrolysis, limit the wide application of pyrolysis product resources. The efficient and selective conversion of tar is complicated by the inherent complexity of sludge and various pollutants (e.g., N-, S-, and Cl-containing organic pollutants, heavy metals) in pyrolysis products, which may either migrate into tar or be released into the environment, complicating the in-depth treatment of tar and posing environmental risks. This review systematically examines the transformation and migration of tar and related secondary pollutants during sludge pyrolysis in order to optimize the pyrolysis process for resource recovery. We provide an overview of the research progress on tar generation, transformation, and secondary pollutants during pyrolysis; discuss potential control strategies for pollution abatement; and highlight the importance of understanding tar transformation during pyrolysis. Additionally, we offer insights into future development trends and research hotpots in this field. This review aims to deliver valuable information on the mechanism of tar formation, the conversion pathways of secondary pollutants, and corresponding control strategies, thus guiding the design and optimization of sludge pyrolysis processes to achieve higher efficiency and selectivity, with minimal environmental pollution. [ABSTRACT FROM AUTHOR]

A co-pyrolysis of woodchips and oil shale was conducted in a continuous reactor at 520 °C in a CO2 atmosphere. Experimental product yields were derived and an analysis of the liquid products was conducted, using gas chromatography, infrared spectroscopy, and physicochemical analysis. A maximum yield of liquids and gases was obtained as the share of biomass increased (43.9 and 35.1 wt%, respectively). Product characterization confirmed additive behavior in co-pyrolysis. The liquid products from copyrolysis blends exhibited fewer oxygenated compounds, derived from biomass, and fewer aromatic compounds, derived from oil shale. Co-pyrolysis liquids contained abundant aliphatic hydrocarbons (C6 to C11). [ABSTRACT FROM AUTHOR]

Abstract Low-cost and green preparation of efficient sorbents is critical to the removal of organic contaminants during water treatment. In this study, the co-pyrolysis of macroalgae and oyster shell was designed to synthesize nitrogen-doped porous biochars for sorption removal of atrazine from water. Oyster shell played a significant role in opening pores in macroalgae-derived biochars, resulting in the surface area of the macroalgae (Enteromorpha prolifera and Ulva lactuca) and oyster shell co-pyrolyzed carbonaceous as high as 1501.80 m2 g−1 and 1067.18 m2 g−1, the pore volume reached 1.04 cm3 g−1 and 0.93 cm3 g−1, and O/C decreased to 0.09 and 0.08, respectively. The sorption capacity of atrazine to nitrogen-doped porous biochars (the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous) reached 312.06 mg g−1 and 340.52 mg g−1. Pore-filling, hydrogen bonding, π-π or p-π stacking and electrostatic interaction dominated the multilayer sorption process. Moreover, the nitrogen-doped porous biochars showed great performance in cyclic reusability, and the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous sorption capacity still reached 246.13 mg g−1 and 255.97 mg g−1, respectively. Thus, this study suggested that it is feasible and efficient to remove organic contaminants with the nitrogen-doped porous biochars co-pyrolyzed from macroalgae and oyster shell, providing a potential green resource utilization of aquatic wastes for environmental remediation. Graphical Abstract

A co-pyrolysis of woodchips and oil shale was conducted in a continuous reactor at 520 °C in a CO2 atmosphere. Experimental product yields were derived and an analysis of the liquid products was conducted, using gas chromatography, infrared spectroscopy, and physicochemical analysis. A maximum yield of liquids and gases was obtained as the share of biomass increased (43.9 and 35.1 wt%, respectively). Product characterization confirmed additive behavior in co-pyrolysis. The liquid products from co-pyrolysis blends exhibited fewer oxygenated compounds, derived from biomass, and fewer aromatic compounds, derived from oil shale. Co-pyrolysis liquids contained abundant aliphatic hydrocarbons (C6 to C11).

Abstract Pyrolytic synergistic interactions, in which the production of pyrolyzates is enhanced or inhibited, commonly occur during the co-pyrolysis of different polymeric materials, such as plastics and biomass. Although these interactions can increase the yield of desired pyrolysis products under controlled degradation conditions, the desired compounds must be separated from complex pyrolyzates and further purified. To balance these dual effects, this study was aimed at examining pyrolytic synergistic interactions during slow heating co-pyrolysis of biodegradable plastics including polylactic acid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexaoate) (PHBH) and petroleum-based plastics including high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). Comprehensive investigations based on thermogravimetric analysis, pyrolysis–gas chromatography/mass spectrometry, and evolved gas analysis-mass spectrometry revealed that PLA and PHBH decompose at lower temperatures (273–378 °C) than HDPE, PP, and PS (386–499 °C), with each polymer undergoing independent decomposition without any pyrolytic interactions. Thus, the independent pyrolysis of biodegradable plastics, such as PLA and PHBH, with common plastics, such as HDPE, PP, and PS, can theoretically be realized through temperature control, enabling the selective recovery of their pyrolyzates in different temperature ranges. Thus, pyrolytic approaches can facilitate the treatment of mixed biodegradable and common plastics.

A carbon material Cu-corn straw-sludge biochar (Cu-CSBC) was prepared by hydrothermally modifying sewage sludge and corn stover. The composite coupled to ultrasound can effectively catalyze the activation of PS for organic pollutants degradation, and the removal rate of 20 mg/L TC reached 89.15% in 5 min in the presence of 0.5 g/L Cu-CSBC and 3 mM PS. The synergistic effect between the factors in the system, the reaction mechanism, and the efficient removal of TC in the aqueous environment were explored in a Cu-CSBC/US/PS system established for that purpose. Quenching experiments and electron paramagnetic resonance analysis both demonstrated the Cu-CSBC/US/PS system generated •OH, SO4–•, 1O2, and O2- •, which involved in the reaction. The Cu, carboxyl, and hydroxyl groups on the Cu-CSBC surface promoted the generation of radicals and non-radicals for the degradation process, which was dominated by both radical and non-radical pathways. The degradation pathway is proposed by measuring the intermediate products with LC-MS. Finally, the stability of the Cu-CSBC/US/PS system was tested under various reaction conditions. This study not only prepared a novel biochar composite material for the active degradation of organic pollutants by PS but also provided an effective method for the resource utilization of solid waste and sludge treatment. HIGHLIGHTS Cu-CSBC prepared from co-pyrolyzed biomass–sludge to activate PS.; US and Cu-CSBC have a positive synergistic effect on the system.; The TC removal efficiency of the Cu-CSBC/US/PS system exceeded 99%.; The US can promote the production of free radicals in the system.; The main intermediates and pathways of TC degradation were identified.;

Biomass has been suggested as a sustainable alternative to substitute fossil fuels. Based on the pyrolysis method, the biomass would be converted into energy through decomposition by thermal degradation under an inert atmosphere, resulting in charcoal, liquid, and gas products. The quality of oils is effectively enhanced through the pyrolysis of lignocellulosic biomass and plastic due to the facilitation of deoxygenation by plastics. This study investigates the impact of incorporating low-density polyethylene (LDPE) plastic in co-pyrolysis with sago dregs (SDs) waste. Pyrolysis of SDs and LDPE mixtures with ratios of 5:1, 4:2, 3:3, 2:4, and 1:5 at various temperatures of 375°C, 425°C, and 475°C. The maximum oil yield obtained for SDs and LDPE pyrolysis was 44.94%. The calorific value (CV) of all observed compositions is a minimum of 10,579.57 kcal kg-1 and a maximum of 11,545.21 kcal kg-1. The gas chromatography-mass spectroscopy (GC-MS) analysis confirmed the interaction between SDs and LDPE on co-pyrolysis. The addition of LDPE will produce rich aliphatic and aromatic compounds, like the proportions of alkanes (45.53%), alkenes (30.62%), alcohol (0.4%), and benzene (17.68%). Co-pyrolysis of SDs and LDPE promotes enhanced oil production by reducing oxygenated compounds and increasing hydrocarbon compounds.

Abstract Co-pyrolysis of chicken manure with tree bark was investigated to mitigate salinity and potentially toxic element (PTE) concentrations of chicken manure-derived biochar. The effect of tree bark addition (0, 25, 50, 75 and 100 wt%) on the biochar composition, surface functional groups, PTEs and polycyclic aromatic hydrocarbons (PAH) concentration in the biochar was evaluated. Biochar-induced toxicity was assessed using an in-house plant growth assay with Arabidopsis thaliana. This study shows that PTE concentrations can be controlled through co-pyrolysis. More than 50 wt% of tree bark must be added to chicken manure to reduce the concentrations below the European Biochar Certificate-AGRO (EBC-AGRO) threshold. However, the amount of PAH does not show a trend with tree bark addition. Furthermore, co-pyrolysis biochar promotes plant growth at different application concentrations, whereas pure application of 100 wt% tree bark or chicken manure biochar results in decreased growth compared to the reference. In addition, increased plant stress was observed for 100 wt% chicken manure biochar. These data indicate that co-pyrolysis of chicken manure and tree bark produces EBC-AGRO-compliant biochar with the potential to stimulate plant growth. Further studies need to assess the effect of these biochars in long-term growth experiments.

Leucaena leucocephala, an invasive toxic tree species, has threatened the survival of native plants in the Hengchun Peninsula, southern Taiwan. Due to the small-to-medium diameter, the utilization and processing of L. leucocephala is highly restricted, while its discarding accelerates carbon dioxide emission to the atmosphere. Biochar, produced from the pyrolysis of biomass under an inert atmosphere, is considered an effective carbon sequestration technique with high stability, which is important for long-term carbon storage and soil improvement. L. leucocephala biomass and montmorillonite were co-pyrolyzed under inert conditions, aiming to investigate the effects of different pyrolysis temperatures and montmorillonite blending ratios on biochar yield and carbon retention. Results showed improved biochar yield and carbon retention with increasing montmorillonite addition. Thermogravimetric analysis, nuclear magnetic resonance spectroscopy, and Fourier-transform infrared spectroscopy demonstrated enhanced stability of the modified biochars. The production of modified L. leucocephala biochar represents a promising technique for carbon dioxide sequestration and biochar stabilization, enabling the development of L. leucocephala utilization approaches.

The co-pyrolysis (at 300°C and 600°C) of municipal sewage sludge (SS) with zero-valent iron (Fe0: 1.5% and 3%) was investigated to reduce the toxicity of arsenic (As) and zinc (Zn) in SS. The BCR sequential extraction method, desorption kinetic analysis, and material characterization techniques (Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray diffraction) were used to evaluate the effects of the treatments on Zn and As behavior. The results showed that co-pyrolysis significantly reduced the acid-soluble fraction (18–43% for Zn; 83–95% for As) and mobility factor (45–85% for Zn; 86–96% for As) of Zn and As compared to untreated SS. Desorption experiments indicated a significant reduction in Zn and As release in treated samples, particularly in the co-pyrolysis sample at 600°C and Fe0 3% (67% for Zn; 88% for As) in comparison with untreated SS. Co-pyrolysis of Fe0 and SS led to the formation of new functional groups (Si–O, aromatic), a more porous surface morphology, and highly stable chemical crystals (ferric arsenate, zinc arsenide), which played a crucial role in Zn and As stabilization. The findings of this study suggest that co-pyrolysis is a promising approach for mitigating As and Zn toxicity in SS. However, additional field testing with plant-based systems is necessary for confirmation.

Co-pyrolysis of chicken manure with tree bark was investigated to mitigate salinity and potentially toxic element (PTE) concentrations of chicken manure-derived biochar. The effect of tree bark addition (0, 25, 50, 75 and 100 wt%) on the biochar composition, surface functional groups, PTEs and polycyclic aromatic hydrocarbons (PAH) concentration in the biochar was evaluated. Biochar-induced toxicity was assessed using an in-house plant growth assay with Arabidopsis thaliana. This study shows that PTE concentrations can be controlled through co-pyrolysis. More than 50 wt% of tree bark must be added to chicken manure to reduce the concentrations below the European Biochar Certificate-AGRO (EBC-AGRO) threshold. However, the amount of PAH does not show a trend with tree bark addition. Furthermore, co-pyrolysis biochar promotes plant growth at different application concentrations, whereas pure application of 100 wt% tree bark or chicken manure biochar results in decreased growth compared to the reference. In addition, increased plant stress was observed for 100 wt% chicken manure biochar. These data indicate that co-pyrolysis of chicken manure and tree bark produces EBC-AGRO-compliant biochar with the potential to stimulate plant growth. Further studies need to assess the effect of these biochars in long-term growth experiments. [ABSTRACT FROM AUTHOR]

The search of sustainable route for biofuel production from renewable biomass have garnered wide interest to seek for various routes without compromising the environment. Co-pyrolysis emerges as a promising thermochemical route that can improve the pyrolysis output from simultaneously processing more than two feedstocks in an inert atmosphere. This paper focuses on the kinetic modeling and neuro-evolution optimization in the application of catalytic co-pyrolysis of microalgae and plastic waste using HZSM-5 supported on limestone (HZSM-5/LS), in which co-pyrolysis of binary mixture of microalgae and plastic wastes (i.e. High-Density Polyethylene and Low-Density Polyethylene) was investigated over different heating rates. The results have shown a positive synergistic effect between the microalgae and polyethylene in which the apparent activation energies values have reduced significantly (-20 kJ/mol) compared to that obtained by pyrolysis of individual microalgae component. The kinetic models reflect that the mixture of microalgae and Low-Density Polyethylene for use as co-pyrolysis feedstock requires activation energy that is 23% and 13% lower compared to that required by pure microalgae and the mixture of microalgae and High-Density Polyethylene, respectively. The Progressive Depth Swarm-Evolution (PDSE) was used for neural architecture search, which subsequently provided optimal reaction condition at 873 K can achieve 99.6 % of degradation rate using a tri-combination of LDPE (0.13 %) + HDPE (0.77 %) + MA (0.11 %) in the presence of HZSM-5/LS catalyst. [ABSTRACT FROM AUTHOR]

The recycling of plastic packaging wastes helps to alleviate the problems of white pollution and resource shortage. It is very necessary to develop high-value conversion technologies for plastic packaging wastes. To our knowledge, carbon materials with excellent properties have been widely used in energy storage, adsorption, water treatment, aerospace and functional packaging, and so on. Waste plastic packaging and biomass materials are excellent precursor materials of carbon materials due to their rich sources and high carbon content. Thus, the conversion from waste plastic packaging and biomass materials to carbon materials attracts much attention. However, closely related reviews are lacking up to now. In this work, the pyrolysis routes of the pyrolysis of plastic packaging wastes and biomass materials for conversion to high-value carbons and the influence factors were analyzed. Additionally, the applications of these obtained carbons were summarized. Furthermore, the limitations of the current pyrolysis technology are put forward and the research prospects are forecasted. Therefore, this review can provide a useful reference and guide for the research on the pyrolysis of plastic packaging wastes and biomass materials and the conversion to high-value carbon. [ABSTRACT FROM AUTHOR]

This study investigates the effects of varying temperatures on the co-pyrolysis of wood sawdust (WS) and waste tires (WT) within a stainless steel fixed-bed reactor under a nitrogen atmosphere. The experiments were conducted at three different temperatures: 400 °C, 500 °C, and 600 °C, focusing on the thermal behavior and resultant product yields. At 600 °C, WS produced the highest oil yield (63.6 wt%), suggesting a tendency to generate more aqueous and volatile components. Conversely, WT alone showed an optimal oil yield of 46.4 wt% at 500 °C, while the WS-WT blend achieved 55.6 wt%. Gas chromatography-mass spectrometry (GC-MS) analyses of the pyrolytic oils indicated that WS-heavy mixtures were rich in aliphatic compounds, whereas WT-dominant samples had increased aromatic and phenolic contents, demonstrating the potential for creating valuable chemicals from waste. Additionally, gas analysis highlighted significant variations in syngas composition, with increased methane and decreased CO2 levels at higher temperatures, emphasizing the role of the water-gas shift reaction. These findings underscore the critical importance of temperature control in optimizing the efficiency and quality of products from co-pyrolysis, presenting a viable method for enhancing the value derived from waste materials.

Bakelite, a thermosetting plastic, is harder to recycle as compared to than thermoplastic polymers through thermal method due to its inherent property to harden on application of heat. This study co-pyrolyzes waste bakelite with polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethyl methacrylate (PMMA) in a conventional semi-batch pyrolysis reactor and microwave pyrolysis reactor to determine how the reactor type and thermoplastic blending affect product distribution, yield, and composition of condensable fraction. The blending of thermoplastics and pyrolysis reactor types greatly affects product distribution. Bakelite, on pyrolysis, produces 39.12 wt% condensable product, which increased to 45.42 wt%, 58.76 wt%, 61.53 wt%, and 66.76 wt% in conventional pyrolysis and 49.87 wt%, 61.26 wt%, 66.51 wt%, and 72.88 wt% in microwave pyrolysis by blending HDPE, PP, PMMA, and PS respectively. The composition analysis through Gas chromatography-mass spectrometry and Fourier-transformed infrared spectroscopy confirms the formation of alkanes, cycloalkanes, alkenes, cycloalkenes, aromatics, and oxygenated compounds, from both pyrolysis processes. However, their percentage differ significantly in both processes. Microwave-assisted pyrolysis with activated carbon yields superior oil in both quantity and composition compared to conventional pyrolysis, effectively transforming waste plastics into valuable products.

The present study uncovered the effect of pyrolysis temperature (400, 500, 600, and 700 °C), and biomass-to-plastic ratio (100:0, 25:75, 50:50, 75:25, 0:100) on the product distribution and synergistic effect during co-pyrolysis of palm kernel shell (PKS) and medical bottle (MB). The highest bio-oil yield of 65.93 wt% was attained at 500 °C and PKS:MB ratio of 25:75. To determine the synergistic effect, the product distributions (yield and chemical composition) were compared with those obtained from pyrolysis of individual components. The positive synergistic effect on the production of hydrocarbons and inhibition of acids were most dominant at PKS:MB ratio of 75:25. The presence of PKS-derived oxygen radicals and hydrogen abstraction from MB can accelerate the formation of hydrocarbons via secondary cracking and deoxygenation reaction. The produced oil at PKS:MB ratio of 50:50 showed better characteristics compared to PKS-derived oil which contains higher carbon (45 % higher), and hydrogen content (66 % higher), and lower oxygen content (71 % lower).

Biomass and plastics are two of the most common municipal solid wastes globally that have continuously placed a burden on the environment. It is therefore important that they are properly recycled. Thermochemical co-conversion offers a valuable opportunity to recycle biomass and plastics simultaneously into biochar, which reduces the time and cost of recycling them individually while producing a material with a wide range of applications. This study is a review of published literature that discusses the thermochemical co-processing of biomass and plastic wastes into biochar. It was observed that co-pyrolysis and co-hydrothermal carbonization are the most commonly utilized technologies for this process. The characteristics of different biomass and plastics that have been thermochemically converted into biochar were compared. The properties of the resulting biochar are affected by the feedstock composition, pre-treatment and blending ratio, the reactor’s configuration, reaction temperature, and the presence of a catalyst. Most studies found that treating the feedstocks separately resulted in a lower yield of biochar than processing them together. The biochar created by this procedure has been used as a soil additive and as an adsorbent for water treatment. Future perspectives and suggestions, such as the necessity for some technical advancement, biochar's economic benefits, improved government participation, and raised social awareness, were also made. These factors have the potential to propel this field of study to great horizons.

In this study, pyrolysis and co-pyrolysis of commonly used plastic materials (polyethylene terephthalate – PET, high density polyethylene – HDPE, and polystyrene – PS) were conducted to analyse the chemical composition of the corresponding pyrolyzates. Different ratios of plastic materials were applied to obtain a composition of aliphatic and aromatic degradation products that closely resemble those of conventional fossil fuels. The systematic chemical variations can act as base for evaluating this approach as a sustainable source of alternative fuels. HDPE revealed an aliphatic composition of degradation products, while PS and PET produced only aromatic compounds. Quantitative analysis of the obtained pyrolyzates revealed a clear correlation of initial proportion with the resulting quantitative product composition. The generation of individual pyrolysis products gave a high reproducibility. However, it became evident that the decomposition products of PS consistently emerged as the most prominent among all tested HDPE/PS mixtures. The ratio of HDPE:PS = 1:3 showed 96 % of the aromatic compounds as PS decomposition products. PET revealed a oxygen containing structure of the products, contributing to 83 % of the HDPE:PET = 1:3 mixture. These results gain insights into the potential of plastic waste as a sustainable source for alternative fuels and valuable chemicals.

The co-pyrolysis of biomass and fossil fuels has been the subject of studies on sustainable energy. Co-feeding oil shale with woody biomass can contribute to a transition into carbon neutrality. The present study analysed the thermal decomposition behaviour of oil shale and biomass blends (0:1, 3:7, 1:1, 7:3, 9:1, and 1:0) through thermogravimetric analysis (TGA) at 80–630 °C with a heating rate of 10 °C/min in CO2 and N2 atmospheres. A comparison of theoretical and experimental residual mass yields of oil shale–biomass mixtures indicated no significant interactions between the fuels. The blends contributed to a decrease of up to 34.4 wt% in solid residues compared to individual pyrolysis of oil shale, and the TGA curves were shifted from up to 10 °C to a lower temperature when the biomass ratio increased. The use of a CO2 atmosphere resulted in the production of solid residues, comparable to the one obtained with the N2 atmosphere. CO2 atmosphere can be used in oil shale–biomass co-pyrolysis, without affecting the decomposition process or increasing the yield of residues. A kinetic model method is proposed based on TGA data at 10, 20, and 30 °C/min. The apparent activation energies for a temperature range of 200–520 °C were in the order of 139, 155, 164, 197, 154, and 167 kJ/mol for oil shale–biomass 0:1, 3:7, 1:1, 7:3, 9:1, and 1:0 blends, respectively. From the isoconversional kinetic analysis, a two-stage pyrolysis was observed, which separated biomass and oil shale pyrolysis. A simulation of biomass and oil shale co-pyrolysis was conducted in Aspen Plus® using TGA-derived kinetic data. The model prediction resulted in a close match with the experimental thermogravimetric data with absolute errors from 1.75 to 3.78%, which highlights the relevance of TGA analysis in simulating co-pyrolysis processes. [ABSTRACT FROM AUTHOR]

Biomass and plastics are two of the most common municipal solid wastes globally that have continuously placed a burden on the environment. It is therefore important that they are properly recycled. Thermochemical coconversion offers a valuable opportunity to recycle biomass and plastics simultaneously into biochar, which reduces the time and cost of recycling them individually while producing a material with a wide range of applications. This study is a review of published literature that discusses the thermochemical co-processing of biomass and plastic wastes into biochar. It was observed that co-pyrolysis and co-hydrothermal carbonization are the most commonly utilized technologies for this process. The characteristics of different biomass and plastics that have been thermochemically converted into biochar were compared. The properties of the resulting biochar are affected by the feedstock composition, pre-treatment and blending ratio, the reactor's configuration, reaction temperature, and the presence of a catalyst. Most studies found that treating the feedstocks separately resulted in a lower yield of biochar than processing them together. The biochar created by this procedure has been used as a soil additive and as an adsorbent for water treatment. Future perspectives and suggestions, such as the necessity for some technical advancement, biochar's economic benefits, improved government participation, and raised social awareness, were also made. These factors have the potential to propel this field of study to great horizons. [ABSTRACT FROM AUTHOR]

Melamine-impregnated paper waste (MIPW) is an unavoidable byproduct of the melamine-impregnated paper production process, and it must be urgently disposed. In this paper, due to its high N content, MIPW was used as a N source to co-pyrolyze with camellia oleifera shell (COS). By changing the proportion of MIPW in the raw materials, the migration path of the N was studied during the co-pyrolysis process. X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), total nitrogen analysis (TN) and ultraviolet spectrophotometry were used to determine the content and the types of N-containing components in raw materials and products. The results showed that during the co-pyrolysis process, the N in MIPW and COS would be converted into different types of N-containing components, and the proportion of MIPW in raw materials directly impacts the product distribution and the N migration path. With the increase in the proportion of MIPW from 10 to 50 wt.% (daf, mass ratio), the proportion of N in raw materials that migrated into the solid phase decreased from 27.58 to 16.31 wt.%, while that which migrated to the gas and liquid phases increased from 24.92 and 47.50 wt.% to 25.97 and 57.72 wt.%, respectively. The proportions of N in the raw materials that changed into pyridinic-N, pyrrolic-N and graphitic-N in the solid phase and N2-N in the gas phase were decreased. The proportions of NH3-N and HCN-N in the gas phase and NH3-N and organic-N in the liquid phase were increased. Moreover, synergies were observed during the co-pyrolysis process, which affected the N migration path in the raw material. This study will provide policy directions and theoretical support for the comprehensive utilization of MIPW and COS. [ABSTRACT FROM AUTHOR]

The emission of chlorinated pollutants is one of the main problems when recovering copper (Cu) via pyrolysis from waste enameled wires. This is mainly attributed to other wastes which possess high poly(vinyl chloride) content, such as electrical wires and cables, which are often recycled together with enameled copper wires. In this research, to control the chlorinated pollutants, copper(II) oxide (CuO) was chosen and demonstrated to be an efficient dechlorinating agent, and CuO did not introduce any impurities that influence the quality of the recovered Cu. The pyrolysis and co-pyrolysis of polyester enameled wires, PVC, and CuO were investigated, and special attention was paid to chlorinated compounds in released pyrolytic products. In particular, the co-pyrolysis of this ternary mixture was studied for the first time, and some new pyrolysis behaviors were discovered. For example, the results of Py-GC/MS analyses showed that the addition of CuO removed about 75% of the chloro-organic products, the main types of which were chloroaromatic compounds rather than the more toxic chloroesters. Moreover, pyrolysis gases were collected and characterized via ion chromatography, and the results showed that the chlorine content in the pyrolysis gases decreased by about 71%. TG analysis indicated that CuO only minimally affected the pyrolysis of polyester paint. However, through the chlorine fixation effect, CuO influenced the dechlorination and dehydrochlorination of PVC, as well as secondary reactions between HCl and pyrolysis products of polyester paint, therefore changing the products and behaviors of co-pyrolysis. Mechanism of reducing chlorine-containing pollutants and reaction mechanism of forming typical pyrolysis products closely correlated to the effects of CuO were also proposed, providing theoretical guidance for the recycling of waste enameled wires. [ABSTRACT FROM AUTHOR]

In this study, thermo-catalytic co-pyrolysis of different high-molecular weight hydrocarbon mixtures (Fischer–Tropsch paraffin mixture, heavy residue of waste polyethylene thermal cracking and waste polyethylene from agricultural sector) was studied in a two-zone semi-batch reactor system at 450 °C, using Beta zeolite catalyst. The yields and compositions of co-pyrolysis products were studied depending on feedstock, catalyst and its placement (one or two-step pyrolysis). Some results were compared to our previous work, when catalyst free or thermal pyrolysis was compared with ZSM-5 promoted thermo-catalytic pyrolysis with the same feedstocks and layout as in the present case. It was found that the two-step pyrolysis (placing the Beta-zeolite in the 2nd reactor) resulted more gaseous product with higher hydrogen and methane content. In terms of liquid products, the composition shifted towards the heavy ends, which means that the C21+ and diesel fuel boiling ranged hydrocarbon content became higher, comparing to the one-step pyrolysis. In terms of feedstock composition, it was concluded that the higher Fischer–Tropsch wax and waste polyethylene contents enhance the gas and gasoline formation, while heavy residue obtained from waste polyethylene pyrolysis contributed to the formation of JET fuel-like hydrocarbons in higher amount if the catalyst were placed in the 1st reactor. [ABSTRACT FROM AUTHOR]

Recent studies have reported that Fenton sludge and biochemical sludge contain high concentrations of toxic substances and heavy metals (HMs), whereas improper treatment can pose serious threats to environmental safety. Pyrolysis is considered an efficient technology to replace conventional sludge treatment. This study investigated the pyrolysis and kinetic processes of Fenton sludge and biochemical sludge, revealed the physicochemical properties of sludge biochar, and highlighted the role of co-pyrolysis in sludge immobilization of HMs and environmental risks. Results showed that Fenton sludge and biochemical sludge underwent three stages of weight loss during individual pyrolysis and co-pyrolysis, especially co-pyrolysis, which increased the rate of sludge pyrolysis and reduced the decomposition temperature. The kinetic reaction indicated that the activation energies of Fenton sludge, biochemical sludge, and mixed sludge were 11.59 kJ/mol, 8.50 kJ/mol, and 7.11 kJ/mol, respectively. Notably, co-pyrolysis reduced the activation energy of reactions and changed the specific surface area and functional group properties of the biochar produced from sludge. Meanwhile, co-pyrolysis effectively immobilized Cu, Pb, and Zn, increased the proportion of metals in oxidizable and residual states, and mitigated the environmental risks of HMs in sludge. This study provided new insights into the co-pyrolysis properties of sludge biochar and the risk assessment of HMs. [ABSTRACT FROM AUTHOR]

Thermochemical conversion of biomass and petrochemical wastes blend is an excellent method to produce valuable fuels and reduce environmental pollution. Bio-oil production via blending of paulownia wood and polypropylene plastic was investigated in a fixed bed horizontal reactor at different reaction temperatures and different Polymer/Biomass weight ratios. Biomass showed the highest amount of bio-oil production (52.8 wt.%) at 500°C. The results show that with increase in temperature, the production of lighter products (with lower carbon number) has increased. Co-pyrolysis on a horizontal reactor showed positive synergy for the production of liquid and gaseous products. Bio-oil production increased to 61.03 wt.% and the relative oxygen content of the liquid products decreased. In co-pyrolysis with the ratio of 60:40 of PAW: PP, aromatic compounds with 35% by weight constitute the highest amount of liquid product and production of furans and aldehyde/ketones reduced. While this number is equal to 8% for blend of 5% PP and 95% PAW. [ABSTRACT FROM AUTHOR]

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME.

Pyrolysis conversion offers the advantages of significant waste reduction and potential energy recovery. This work examined the potential of combining plastic and agricultural wastes as pyrolysis feedstocks. The mixture of waste low-density polyethylene and Pongamia pinnata seeds was analysed using differential and thermogravimetric methods. In addition to the Coats-Redfern (CR) method, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Friedman (FRM), and Kissinger (KN) model-free methods were also applied to calculate the kinetic parameters. The apparent activation energy (Ea) calculation demonstrated that the co-pyrolysis conversion required Ea values of 125–154 kJ mol−1. The artificial neural network (ANN) model was considered to validate thermogravimetric data. The R2 values were near unity in training, validation, and testing conditions, with the minimum possible value for mean square error obtained for the considered heating rates. The Pongamia pinnata seeds and waste plastic mixture could surely be utilized to lessen environmental degradation, add value to leftover seeds and waste low-density polyethylene by extracting fuel for transportation and other commercial activities, and produce industrial chemicals, as found through the kinetic modelling, thermodynamic parameters, and ANN modelling.

The disposal of municipal sewage sludge (MSS) from wastewater treatment plants poses a major environmental challenge due to the presence of inorganic and organic pollutants. Co-pyrolysis, in which MSS is thermally decomposed in combination with biomass feedstocks, has proven to be a promising method to immobilize inorganic pollutants, reduce the content of organic pollutants, reduce the toxicity of biochar and improve biochar’s physical and chemical properties. This part of the review systematically examines the effects of various co-substrates on the physical and chemical properties of MSS biochar. This review also addresses the effects of the pyrolysis conditions (temperature and mixing ratio) on the content and stability of the emerging pollutants in biochar. Finally, this review summarizes the results of recent studies to provide an overview of the current status of the application of MSS biochar from pyrolysis and co-pyrolysis for the remediation of HM-contaminated soils. This includes consideration of the soil and heavy metal types, experimental conditions, and the efficiency of HM immobilization. This review provides a comprehensive analysis of the potential of MSS biochar for environmental sustainability and offers insights into future research directions for optimizing biochar applications in soil remediation.

In this study, the co-pyrolysis of sewage sludge (SS), two-component special municipal waste (SMW) and plastic waste (Plastic) was studied using thermogravimetric equipment and a scaled-up tubular reactor. During the experiments, the effects of the raw material composition and pyrolysis temperature on the decomposition processes, the product yields and compositions were investigated. It was found that co-pyrolysis was a series of complex reactions and resulted in more volatile and lower residue yield than the pyrolysis of the individual raw materials. In some cases (e.g., 25%SMW + 75%Plastic, 25%SS + 75%Plastic, 50%SS + 50%Plastic blends), it also caused a higher synthesis gas yield and H2/CO ratio. During the thermogravimetric analysis, the beneficial effects occurred at lower temperatures, but in the scaled-up experiments, these effects only prevailed at 900 °C as a result of the larger amount of raw materials and the worse heat transfer. The produced gases can be characterized by a lower heating value of 17.3–35 MJ/Nm3. Therefore, they can be used for energetic purposes; however, before chemical use, further quality improvement is needed due to the lower H2/CO ratios.

With the increasing production of municipal sewage sludge (MSS) worldwide, the development of efficient and sustainable strategies for its management is crucial. Pyrolysis of MSS offers several benefits, including volume reduction, pathogen elimination, and energy recovery through the production of biochar, syngas, and bio-oil. However, the process can be limited by the composition of the MSS, which can affect the quality of the biochar. Co-pyrolysis has emerged as a promising solution for the sustainable management of MSS, reducing the toxicity of biochar and improving its physical and chemical properties to expand its potential applications. This review discusses the status of MSS as a feedstock for biochar production. It describes the types and properties of various co-substrates grouped according to European biochar certification requirements, including those from forestry and wood processing, agriculture, food processing residues, recycling, anaerobic digestion, and other sources. In addition, the review addresses the optimization of co-pyrolysis conditions, including the type of furnace, mixing ratio of MSS and co-substrate, co-pyrolysis temperature, residence time, heating rate, type of inert gas, and flow rate. This overview shows the potential of different biomass types for the upgrading of MSS biochar and provides a basis for research into new co-substrates. This approach not only mitigates the environmental impact of MSS but also contributes to the wider goal of achieving a circular economy in MSS management.

Sewage sludge has long been perceived as the bottleneck of wastewater treatment plants in China, restraining the healthy development of sewage treatment for decades. In recent years, pyrolysis as a promising multifunctional platform has attracted increasing interest for converting sludge into valuable resources. However, the generation and presence of pyrolysis tar, one of the key by-products during sludge pyrolysis, limit the wide application of pyrolysis product resources. The efficient and selective conversion of tar is complicated by the inherent complexity of sludge and various pollutants (e.g., N-, S-, and Cl-containing organic pollutants, heavy metals) in pyrolysis products, which may either migrate into tar or be released into the environment, complicating the in-depth treatment of tar and posing environmental risks. This review systematically examines the transformation and migration of tar and related secondary pollutants during sludge pyrolysis in order to optimize the pyrolysis process for resource recovery. We provide an overview of the research progress on tar generation, transformation, and secondary pollutants during pyrolysis; discuss potential control strategies for pollution abatement; and highlight the importance of understanding tar transformation during pyrolysis. Additionally, we offer insights into future development trends and research hotpots in this field. This review aims to deliver valuable information on the mechanism of tar formation, the conversion pathways of secondary pollutants, and corresponding control strategies, thus guiding the design and optimization of sludge pyrolysis processes to achieve higher efficiency and selectivity, with minimal environmental pollution.

Wastewater treatment plants produce solid and semi-solid sludge, which treatment minimises secondary environmental pollution because of wastewater treatment and obtaining new bioproducts. For this reason, in this paper, the co-pyrolysis of biogenic biomasses recovered from a biological reactor with immobilised fungal and bacterial biomass and a tertiary reactor with Chlorella sp. used for dye-contaminated wastewater treatment was carried out. Biogenic biomasses mixed with pine bark allowed the production and characterisation of two types of biochar. The raw material and biochar were on the "in vitro" germination of Lolium sp. seeds, followed by adsorption studies for malachite green (MG) dye using the raw material and the biochar. Results showed that using 60 mg L−1 of a cationic coagulant at pH 6.5 allowed for the recovery of more than 90% of the microalgae after 50 min of processing. Two biochar resulted: BC300, at pH 5.08 ± 0.08 and BC500, at pH 6.78 ± 0.01. The raw material and both biochars were co-inoculated with growth-promoting bacteria; their viabilities ranged from 1.7 × 106 ± 1.0 × 101 to 7.5 × 108 ± 6.0 × 102 CFU g−1 for total heterotrophic, nitrogen-fixing and phosphate-solubilising bacteria. Re-use tests on Lolium sp. seed germination showed that with the post-coagulation effluent, the germination was 100%, while with the biochar, with and without beneficial bacteria, the germination was 98 and 99%, respectively. Finally, BC500 adsorbed the highest percentage of malachite green at pH 4.0, obtaining qecal values of 0.5249 mg g−1 (R2: 0.9875) with the pseudo-second-order model. [ABSTRACT FROM AUTHOR]

Thermogravimetric and kinetic analysis of biomass and plastic co-pyrolysis can provide valuable inputs for a better understanding decomposition mechanisms. Such inputs are important for selecting the appropriate process conditions but can also be helpful for process modelling. This work investigates the properties of heterogenous sawdust mixed with polypropylene and polystyrene. Thermogravimetric analysis is conducted to determine the decomposition mechanism and kinetic parameters of investigated mixtures and to derive appropriate conclusions regarding their further utilisation potential. Co-pyrolysis was performed on mixtures with the following biomass/plastic ratios: 75-25%, 50-50%, 25-75%, over a temperature range of 30-550 ℃, at four heating rates 5, 10, 20, and 30 ℃/min, with pure argon as a carrier gas. The obtained results were then subjected to comprehensive kinetic and thermodynamic analysis. The primary goal was to determine effective activation energies using model-free methods, preexponential factors, and elementary thermodynamic parameters such as enthalpy, entropy, and free Gibbs energy changes. Finally, the influence of the heating rate and mixture composition was extensively investigated by analysing calculated parameters. [ABSTRACT FROM AUTHOR]

Realizing the utilization of reclaimed asphalt binder (RAB) and rice husk (RH) to reduce environmental pollution and expand the reutilization technique of reclaimed asphalt pavement (RAP), co-pyrolysis of RAB with RH has great potential. In this study, the co-pyrolysis behaviors, gaseous products, and kinetics were evaluated using thermogravimetric analysis and Fourier transform infrared spectroscopy (TG-FTIR). The results showed that incorporating RH into RAB improved its pyrolysis characteristics. The interactions between RAB and RH showed initial inhibition followed by subsequent promotion. The primary gaseous products formed during co-pyrolysis were aliphatic hydrocarbons, water, and carbon dioxide, along with smaller amounts of aldehydes and alcohols originating from RH pyrolysis. All average activation energy values for the blends, determined through iso-conversional methods, decreased with RH addition. The combined kinetic analysis revealed two distinct mechanisms: (1) at the lower conversion range, the pyrolysis of the blend followed a random nucleation and three-dimensional growth mechanism, while (2) at the higher conversion range, the control mechanism transitioned into three-dimensional diffusion. [ABSTRACT FROM AUTHOR]

The safe disposal and resource utilization of Fenton sludge (FS) are challenges due to the presence of heavy metals (HMs). Co-pyrolysis with biomass waste can effectively increase biochar quality and immobilize HMs, but research focusing on heavy metal stabilization from Fenton sludge using the co-pyrolysis approach is scattered. In this study, the co-pyrolysis of FS and pomelo peel (PP) was developed as a strategy to reduce the environmental risk of HMs. The results showed that co-pyrolysis greatly increased the pH and aromaticity of biochars, and the maximum specific surface area was 6.5 times higher than the corresponding FS-based biochar due to the sponge-like structure of PP, which was likely conducive to adsorbing HMs during pyrolysis. Meanwhile, the addition of PP promoted the enrichment of HMs in co-pyrolyzed biochars as well as induced the transformation of bio-available HM fractions to stable forms, especially at high temperatures. Finally, the presence of PP led to the decline in HM leachability in biochars; thus, the potential ecological risks of HMs decreased from considerable pollution levels to moderate and even clean levels. This study demonstrated that co-pyrolysis with PP is a promising approach to reduce the toxicity of HMs and improve the functionality of biochar for industrial sludge management. [ABSTRACT FROM AUTHOR]

Co-pyrolysis is one possible method to handle different biomass leftovers. The success of the implementation depends on several factors, of which the quality of the produced bio-oil is of the highest importance, together with the throughput and constraints of the feedstock. In this study, the fast co-pyrolysis of palm kernel shell (PKS) and woody biomass was conducted in a micro-pyrolyser connected to a Gas Chromatograph–Mass Spectrometer/Flame Ionisation Detector (GC–MS/FID) at 600 °C and 5 s. Different blend ratios were studied to reveal interactions on the primary products formed from the co-pyrolysis, specifically PKS and two woody biomasses. A comparison of the experimental and predicted yields showed that the co-pyrolysis of the binary blends in equal proportions, PKS with mahogany (MAH) or iroko (IRO) sawdust, resulted in a decrease in the relative yield of the phenols by 19%, while HAA was promoted by 43% for the PKS:IRO-1:1 pyrolysis blend, and the saccharides were strongly inhibited for the PKS:MAH-1:1 pyrolysis blend. However, no difference was observed in the yields for the different groups of compounds when the two woody biomasses (MAH:IRO-1:1) were co-pyrolysed. In contrast to the binary blend, the pyrolysis of the ternary blends showed that the yield of the saccharides was promoted to a large extent, while the acids were inhibited for the PKS:MAH:IRO-1:1:1 pyrolysis blend. However, the relative yield of the saccharides was inhibited to a large extent for the PKS:MAH:IRO-1:2:2 pyrolysis blend, while no major difference was observed in the yields across the different groups of compounds when PKS and the woody biomass were blended in equal amounts and pyrolysed (PKS:MAH:IRO-2:1:1). This study showed evidence of a synergistic interaction when co-pyrolysing different biomasses. It also shows that it is possible to enhance the production of a valuable group of compounds with the right biomass composition and blend ratio. [ABSTRACT FROM AUTHOR]

In this study, the effect of oyster shell powder as a substitute for calcium chemical reagents to modify straw biochar for enhancing removal of phosphate and ammonium from aqueous solution was investigated. The results showed that the biochar composite (OSB3:1) with the maximum capacity (151.37 mg·P/g and 0.8 mg·N/g) was synthesized at optimum mass ratio of oyster shell-to-straw (3:1) and pyrolysis temperature (800°C). The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetic models, and it achieved excellent performance at pH 2.0-11.0. According to the thermodynamic analysis, the adsorption reaction was an endothermic and spontaneous process, and increasing the temperature increased the adsorption capacity. The removal mechanisms for phosphate included the formation of hydroxyapatite precipitation, ligand exchange, surface complexation and electrostatic attraction, while for ammonium only electrostatic attraction. The modified biochar can effectively remove phosphate (over 85%) from real domestic sewage within 3 h. Reuse of P-laden biochar as heavy metal adsorbent was proposed, as it exhibited a good removal efficiency for Cd, Zn and Cu, especially application for acidic wastewater. [ABSTRACT FROM AUTHOR]

Waste oil treatment and the burning of fossil fuels are causing environmental problems, thus using waste oils as pyrolysis feedstock to produce high-grade biofuels is receiving a lot of attention. Higher hydrogen and volatile matter contents of waste oils make them an optimal raw material for biofuel production. Conversely, attaining satisfactory effects employing traditional disposal methods such as gasification, solvent extraction, transesterification, membrane technology, and hydro-treating is strenuous. Clean and secure pyrolysis technology can help overcome the present dilemma. Biofuels obtained by the traditional waste oil pyrolysis methods can replace fossil fuel as it has been proven to have a high yield and higher heating value (HHV); however, they contain a high acid value. Nevertheless, treating with metal, zeolites, and other bi-functional catalysts helps decrease the acid value. Energy and time can be effectively saved with improved bio-oil yield and quality by co-pyrolysis with plastic waste. A comprehensive assessment of biofuel production via conventional and progressive pyrolysis of waste oils has been investigated. The current evaluation defines the technical and economical routine for bio-oil production from numerous biomass through pyrolysis. Analyzing the bio-oil production cost is one of the crucial components in determining the market affinity of different alternative biofuels. Bio-oil can be made through biomass pyrolysis using an energy integration approach smoothly. The Life cycle assessment (LCA) of waste oil with co-feeds was also discussed in-depth. The conclusions gained using the following study might influence the research on the bio-oil industry targeted at commercializing the product.

Abstract Biochar modified by metal ions—particularly Mg—is typically used for the effective recovery of phosphorous. In this study, MgO-modified biochars were synthesized via the direct co-pyrolysis of MgO and raw materials such as rice straw, corn straw, Camellia oleifera shells, and branches from garden waste, which were labeled as MRS, MCS, MOT, and MGW, respectively. The resulting phosphate (PO) adsorption capacities and potential adsorption mechanisms were analyzed. The PO adsorption capacities of the biochars were significantly improved after the modification with MgO: MRS (24.71 ± 0.32 mg/g) > MGW (23.55 ± 0.46 mg/g) > MOT (15.23 ± 0.19 mg/g) > MCS (14.12 ± 0.21 mg/g). PO adsorption on the modified biochars was controlled by physical adsorption, precipitation, and surface inner-sphere complexation processes, although no electrostatic attraction was observed. Furthermore, PO adsorbed on modified biochars could be released under acidic, alkaline, and neutral conditions. The desorption efficiency of MRS was modest, indicating its suitability as a slow-release fertilizer. Graphical Abstract

The recycling of plastic packaging wastes helps to alleviate the problems of white pollution and resource shortage. It is very necessary to develop high-value conversion technologies for plastic packaging wastes. To our knowledge, carbon materials with excellent properties have been widely used in energy storage, adsorption, water treatment, aerospace and functional packaging, and so on. Waste plastic packaging and biomass materials are excellent precursor materials of carbon materials due to their rich sources and high carbon content. Thus, the conversion from waste plastic packaging and biomass materials to carbon materials attracts much attention. However, closely related reviews are lacking up to now. In this work, the pyrolysis routes of the pyrolysis of plastic packaging wastes and biomass materials for conversion to high-value carbons and the influence factors were analyzed. Additionally, the applications of these obtained carbons were summarized. Furthermore, the limitations of the current pyrolysis technology are put forward and the research prospects are forecasted. Therefore, this review can provide a useful reference and guide for the research on the pyrolysis of plastic packaging wastes and biomass materials and the conversion to high-value carbon.

In the context of resource utilization, the applications of waste biomass have attracted increasing attention.Previous studies have shown that forming biochar by heat treatment of sludge could replace the traditional sludge disposal methods, and sludge biochar is proved to be efficient in wastewater treatment. In this work, the pyrolysis, hydrothermal carbonization and microwave pyrolysis methods for preparing sludge biochar were reviewed, and the effects of different modification methods on the performance of sludge biochar in the synthesis process were comprehensively analyzed. This review also summarized the risk control of heavy metal leaching in sludge biochar, increasing the pyrolysis temperature and use of the fractional pyrolysis or co-pyrolysis were usually effectively meathods to reduce the leaching risk of heavy metal in the system, which is crucial for the wide application of sludge biochar in sewage treatment. At the same time, the adsorption mechanism of sludge biochar and the catalytic mechanism as the catalytic material in AOPs reaction, the process of radical and non-radical pathway and the possible impacts in the sludge biochar catalytic process were also analyzed in this paper

Abstract The increase in mineral and ash-rich waste biomass (MWB) generation in emerging economies poses critical environmental problems and bottlenecks the solid waste and wastewater treatment systems. Transforming these MWB such as sewage sludge from wastewater treatment (SSW) to biochar can be a sustainable method for their disposal and resource recovery. However, such biochar has limited applicability due to the relatively low organic content and possibly contaminated nature of SSW. This may be offset through combined pyrolysis with other MWB, which can also support municipal solid waste management. Studies on this MWB co-pyrolysis are lacking and have not yet seen successful long-term implementation. This work is the second part of authors’ research encompassing an analytical and lab-scale investigation of biochar production from MWB through pyrolysis for the case of Chennai city, India. Here, the physicochemical properties of biochar derived from lab-scale co-pyrolysis of SSW with other MWB such as anaerobic digestate from waste to energy plants of food, kitchen or market waste fermentation, and banana peduncles (BP) collected from vegetable markets and their thermolysis mechanism are comprehensively investigated for purpose of carbon sequestration. Also, a novel preliminary investigation of the effect of sample weight (scaling effect) on the analytical pyrolysis of biomass (BP as model substrate) is undertaken to elucidate its impact on the heat of pyrolysis and carbon distribution in resultant biochar. The maximum carbon sequestration potential of the derived biochar types is 0.22 kg CO2 kg−1 biomass. The co-pyrolysis of MWB is exothermic and governed by the synergetic effects of the components in blends with emission profiles following the order CO2 > CH4 > CO > NH3. Co-pyrolysis reduced the heavy metal enrichment in SSW biochar. The derived biochars can be an immediate source of N, P and S in nutrient-deficient acidic soils. The biochar has only up to 4-ring polyaromatic compounds and a residence time longer than 1 h at 500 °C is necessary to improve carbonization. The heat released during analytical pyrolysis of the model biomass and distribution of carbon in the resultant biochar are significantly influenced by scaling effects, drawing attention to the need for a more detailed scaling investigation of biomass pyrolysis.

The prediction accuracy of the detailed kinetic mechanisms for aromatic hydrocarbon formation in combustion was assessed and improved for the pyrolysis and co-pyrolysis of C3 and C4 feedstock. Although KAUST PAH Mech 2 was developed mainly for the formation of polycyclic aromatic hydrocarbons in combustion, in this study, it predicted the formation of hydrocarbons with a low molecular weight in pyrolysis, with the highest accuracy for all detailed kinetic mechanisms evaluated. On the other hand, those of benzene and toluene were low with all the detailed kinetic mechanisms evaluated. Several modifications were made to improve accuracy by further examining sensitivity analysis, the results of which suggested that the reactions that produced benzene and toluene from C3 required correction.

As there is an urgent need to address the global problem of increasing plastic waste and decreasing petroleum-based fuels, it is possible to convert waste plastic and unused biomass seeds into fuels that can be utilized in transportation sector. The current study deals with blending pure diesel (D100) with the liquid fuel (PB2) obtained from the co-pyrolysis of Pongamia pinnata seeds and waste low-density polyethylene (LDPE) with Calcium oxide (CaO) as the catalyst. Three blends of D100, namely, PB2@10 (with 10 % blend), PB2@20 (with 20 % blend) and PB2@30 (with 30 % blend) were tested for performance, emission and combustion in an unmodified CI engine for an analytical comparative analysis using standard methods. The results showed that the BSFC was almost same (0.3 kg/kWh) at higher loads for all three blends, while the BTE was found to be equal or increased compared to D100 in the range of 27–30 % at higher loads for higher blends. NOx formation was found to decrease by 19.4 % and 13 % at the highest load for PB2@30 andPB2@30. The smoke formation also decreased for all blends (maximum 22.5 %) while the maximum difference of lambda was determined to have decreased in comparison to D100, close to 1 at higher loads. The maximum cylinder pressure and temperature were also found to have increased during combustion by approximately 1 % for PB2@10 while that of PB2@20 and PB2@30 remained quite close to D100. The obtained renewable liquid fuel could certainly be utilized in blends with pure diesel for use in vehicles.