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This study explored the potential of utilizing aluminum and yttrium amended (Al/Y amended) sewage sludge biochar (Al/Y-CSBC) for efficient fluoride removal from wastewater. The adsorption kinetics of fluoride on bimetallic modified Al/Y-CSBC followed the pseudo-second-order model, while the adsorption isotherm conformed to the Freundlich equation. Remarkably, the material exhibited excellent fluoride removal performance over a wide pH range, achieving a maximum adsorption capacity of 62.44 mg·g−1. Moreover, Al/Y-CSBC demonstrated exceptional reusability, maintaining 95% removal efficiency even after six regeneration cycles. The fluoride adsorption mechanism involved ion exchange, surface complexation, and electrostatic adsorption interactions. The activation and modification processes significantly increased the specific surface area of Al/Y-CSBC, leading to a high isoelectric point (pHpzc = 9.14). The incorporation of aluminum and yttrium metals exhibited a novel approach, enhancing the adsorption capacity for fluoride ions due to their strong affinity. Furthermore, the dispersing effect of biochar played a crucial role in improving defluoridation efficiency by enhancing accessibility to active sites. These findings substantiate the significant potential of Al/Y-CSBC for enhanced fluoride removal from wastewater. [ABSTRACT FROM AUTHOR]

Silicon in soil is critical for crop growth and tolerance to both biotic and abiotic stresses. Si-rich biochar can be used as soil supplements for silicon improvement. In order to investigate the application potential of silicon in pyrolysis biochar (PC) and hydrochar (HC) derived from cow dung digestate (CD), they were compared at different temperatures to explore silicon forms and leaching characteristics. The results indicated that the form and content of silicon changed obviously with variations in pyrolysis temperature. The form of silicon content followed the order of amorphous silicon ≫ available silicon > active silicon > dissolved silicon in PC. For HC, the form of silicon content followed the order of amorphous silicon ≫ dissolved silicon > active silicon > available silicon. Compared to HC, PC had a richer pore-layered structure but fewer surface functional groups. The study of dissolving kinetics of silicon indicated that PC550 released the most silicon, which was 3 times more than HC220. The long-term silicon leaching found that PC550 increased rapidly with reaction time, whose dissolving silicon increased to 33.02 mg/g, which was much higher than the recommended silicon content of soil in China (0.095 mg/g soil). This study offers a novel point of view for anaerobic digestion residue utilization as a fertilizer. • Pyrolysis and HTC enhanced silicon retention in cow dung digestate. • The silicon forms of PC and HC were compared. • The available silicon content in the PC reached 4.94 mg/g. • C-Si interactions in PC were highlighted, in silicon forms and release processes. • PC550 released 33.02 mg/g of silicon, making it optimal for silicon supply. [ABSTRACT FROM AUTHOR]

Previous studies have shown that alkali metals catalyse the pyrolysis and gasification processes of biomass. However, whether alkali metals have the same catalytic effect on the reduction reaction of biochar with iron oxide has not been investigated. In this article, the effect of alkali metals on the reduction behaviour of biochar with iron oxide was investigated. It was shown that adding alkali metal carbonate could increase the reaction rate of CSC reduction stages 1 and 2, but it played an inhibitory role for the first and middle periods of stage 3. Moreover, adding alkali metals resulted in higher total CO2 gas production and reduced total CO gas production for the reduction reaction. The GB1 model was the best mechanistic model for stages 1 and 2 of the CSC-2K and CSC-2Na reduction reactions, while the C1 model was the best mechanistic model for stage 3. [ABSTRACT FROM AUTHOR]

The utilization of biochar, prepared from the agricultural biomass, is one of the economic approaches. To assess the ability of biochar as an adsorbent, sugarcane bagasse-derived biochar was utilized for the removal of phenol from aqueous solution. Phenol, an industrial discharge and a ubiquitous organic pollutant, was chosen as the model compound to determine the adsorption capacity of sugarcane bagasse-derived biochar. The sugarcane bagasse was pyrolyzed at 400, 600, and 800 °C under an N2 atmosphere. Among all the three raw biochars, the biochar obtained at 600 °C showed maximum removal efficiency, 74.2%. Based on higher efficiency, SB-600 biochar was further chemically treated with nitric acid (HNO3) and sodium hydroxide (NaOH) to enhance its adsorption capacity. Sugarcane bagasse-derived magnetic biochar was also fabricated using the pre-pyrolysis modification. Maximum removal (96.1%) efficiency was observed in the case of HNO3-treated calcined biochar compared to the other treated biochars. Adsorption parameters of the calcined-acid treated biochar were optimized through response surface methodology. The maximum adsorption capacity of the calcined-acid treated biochar was 41.3 mg/g. [ABSTRACT FROM AUTHOR]

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development.

Abstract In the present study, the effects of mild air oxidation of a biochar produced by the Pyrovac Inc. pyrolysis process, on the adsorption of lead(II) from synthetic wastewater under batch experimental conditions have been investigated. The adsorption experiments were performed under several conditions suggested by the response surface methodology, which allowed finding the optimal conditions, in order to maximize the adsorption capacity (Q (mg g − 1 )) , as well as the extraction efficiency (E (%)). The optimal conditions of lead ions adsorption were as follows: pH = 5, agitation time = 300 min, adsorbent mass = 0.5 g (per 50 cm3 of solution), and lead initial concentration = 100 g m − 3 , resulted in an adsorption capacity of 7.9 mg g−1. Equilibrium adsorption was then obtained by keeping pH and adsorbent mass at the optimal values and changing the lead initial concentration for a sufficient agitation time. Results showed that mild air oxidation increased the equilibrium adsorption capacity of biochar from 2.5 to 44 mg g−1. Oxidized biochar after equilibrium adsorption was submitted to SEM/EDX and XPS analysis. From SEM it was found that lead particles were distributed heterogeneously after adsorption. From XPS analysis, it was revealed that the external surface of oxidized biochar particles becomes saturated for the initial point of equilibrium diagram, obtained at lead initial concentration of 100 g m − 3 , suggesting that for a higher concentration, the internal surfaces of particles participate in the cations adsorption. The participation of surface functional groups in the adsorption process showed that carbonyl, carboxylic, and aromatic rings of oxidized biochar were involved in the adsorption. This work suggests that the very simple process of mild air oxidation can be used instead of the usual costly chemical activation, in order to improve biochar cation exchange capacity. Graphical abstract Image 1 Highlights • Increasing biochar cation exchange capacity by using simple mild air oxidation. • Involvement of oxygen-containing functional groups in lead cations adsorption. • Correlating processing parameters with oxidized biochar adsorption capacity. [ABSTRACT FROM AUTHOR]

Adding biochar to soil can change soil properties and subsequently affect plant growth, but this effect can vary because of different feedstocks and methods (e.g., pyrolysis or gasification) used to create the biochar. Growth and biological nitrogen fixation (BNF) of leguminous plants can be improved with rhizobia inoculation that fosters nodule development. Thus, this factorial greenhouse study examined the effects of two types of biochar (i.e., pyrolysis and gasification) added at a rate of 5% (v:v) to a peat-based growth substrate and rhizobia inoculation (yes or no) on Robinia pseudoacacia (black locust) seedlings supplied with 15NH415NO3. Seedling and nodule growth, nitrogen (N) content, and δ15N × 1000 were evaluated after 3 months. While addition of biochar without inoculation had no effect on seedling growth, inoculation with rhizobia increased seedling growth, BNF, and N status. Inoculated seedlings had reduced δ15N, indicating that N provided via fertilization was being diluted by N additions through BNF. Biochar type and inoculation interacted to affect seedling growth. Combining inoculation with either biochar type increased seedling leaf, stem, and total biomass, whereas gasifier biochar and inoculation improved all seedling growth variables and nodule biomass.

Environmentally persistent free radicals (EPFRs) are emerging contaminants formed during thermochemical processes. However, the formation and control strategy of EPFRs during the thermochemical process of traditional organic solid waste sludge and biomass is not well understood. This work investigated the EPFRs formations of fly ash and biochar via sampling in running factories and theoretical study on a laboratory scale. The oxygen-centered and carbon-centered EPFRs were detected in the pyrolysis biochar sampled on-site. EPFRs are rarely detected in fresh fly ash from incinerators, which is due to paramagnetic metal interference detection signals and sulfate hindering the potential formation sites of EPFRs. The formation of EPFRs was further detected in the simulated combustion particles, and the characteristics of EPFRs were closely related to the precursor and temperature. Sludge-based biochar (SBC) and rice husk-based biochar (RBC) prepared at different temperatures and residence times were further investigated. The pyrolysis temperature significantly impacted the EPFRs types and spin concentration in the resulting biochar. The pyrolysis temperature of 500 °C resulted in the highest spin concentration of 1.07✕1018 spins/g in RBC. Appropriate residence time could limit EPFRs formation. The minimum spin concentration of EPFRs in RBC and SBC was obtained at 2 h. In addition, adding biomass into sludge pyrolysis could lead to more EPFRs. Controlling the pyrolysis temperature above 500 °C and the residence time of around 2 h can impose restrictions on forming EPFRs. The findings improved the fundamental understanding of EPFRs generation in solid products derived from organic solid waste thermochemical processing, providing an opportunity to control EPFRs production. [Display omitted] • EPFRs in incineration fly ash and pyrolysis residues of sludge and biomass were characterized. • EPFRs were little detected in fly ash from sludge and biomass incineration plants. • Oxygen-centered and carbon-centered EPFRs were positively formed during pyrolysis. • Temperature significantly affects the formation of EPFRs. [ABSTRACT FROM AUTHOR]

Recycling of phosphorus (P) from pyrolysis sewage sludge is a good methodology to deal with the deficit of P resources and safely dispose the sewage sludge. However, it is essential to determine the type of sludge in sewage treatment plants (STPs) along with the most appropriate pyrolysis temperature. These factors affect the form and bioavailability of recoverable P. Thus, four kinds of sludge in a typical STP were selected, and three pyrolysis temperatures including 300, 500, and 700 °C were set to find a suitable strategy for P recovery. The results indicated that with increasing pyrolysis temperature, more organic phosphorus (OP) was transformed into inorganic phosphorus (IP) and more non-apatite inorganic phosphorus (NAIP) was converted to apatite phosphorus (AP, mainly Ca 3 (PO 4) 2 , Ca(H 2 PO 4) 2 , Mg 3 (PO 4) 2 , Ca 3 Mg 3 (PO 4) 4 , and Ca 5 (PO 4) 3 OH). Compared to other sludges, dewatered cake sludge (CS) pyrolyzed at 700 °C had the highest AP content, about 1.1–3.6 times that in other pyrolysis products, and the highest Ca 5 (PO 4) 3 OH content containing 35.8% of total phosphorus (TP). The contents of P-2% citric acid (CA) and neutral ammonium citrate (NAC) in CS obtained by pyrolysis at 500 °C reached 45.6 and 49.6 mg/g, respectively, which were 1.1–3.0 and 1.1–2.8 times that of P-CA and P-NAC in other sludges and their biochars, respectively. Moreover, the diethylenetriaminepentaacetic acid extraction analysis indicated that the good stability of heavy metals in CS-derived biochar was better than that in the feedstock. Hence, to ensure the efficiency and safety of P, CS is used as raw material in STPs to recover P resources. CS-500 can be used as the direct P source of land owing to the highest concentration of bioavailable P (P-CA and P-NAC), while CS-700 can be used to represent a slow-release P fertilizer because it contains the highest concentration of AP. [Display omitted] • High-temperature pyrolysis promoted the conversion of NAIP into AP in sludge. • The AP content of CS-700 was 29.1 mg/g about 1.1–3.6 times that in other biochars. • The fraction of hydroxylapatite in CS-700 achieved 35.8% of TP. • CS-500 had the highest level of P-CA (45.6 mg/g) and P-NAC (49.6 mg/g). • CS has the highest phosphorus recovery potential compared to other sludges in STPs. [ABSTRACT FROM AUTHOR]

The novelty of this study is providing a new toughening strategy in terms of the challenge of improving the poor toughness of zein film. Two types of biochar, pyrolysis biochar (PB) and hydrochar microspheres (HM), were blended into the zein system through solution casting to develop zein composite films with excellent toughness. The effects of biochar types and contents on the mechanical properties of the resulting composite films were investigated. The results indicated that better compatibility of zein composite films was achieved due to the hydrogen bond formed by biochar and hydrophilic amino acid in zein. A better surface structure of HM composite films was obtained than PB composite films by the uniform size and regular shape of HM. Better thermal stability shown in PB contributed to better thermal properties in the zein system than HM. Mechanical properties showed that tensile strength and modulus were increased with increasing PB or HM contents. Although increasing PB or HM contents decreased the elongation at break, the elongation at break reached a maximum of 475.47% at 0.1 g HM added composite film showing excellent toughness due to the strong interface binding and micro-nano size effect. The composite films prepared in this study have broad application prospects in packaging and agricultural films. [ABSTRACT FROM AUTHOR]

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development. [ABSTRACT FROM AUTHOR]

Adding biochar to soil can change soil properties and subsequently affect plant growth, but this effect can vary because of different feedstocks and methods (e.g., pyrolysis or gasification) used to create the biochar. Growth and biological nitrogen fixation (BNF) of leguminous plants can be improved with rhizobia inoculation that fosters nodule development. Thus, this factorial greenhouse study examined the effects of two types of biochar (i.e., pyrolysis and gasification) added at a rate of 5% (v:v) to a peat-based growth substrate and rhizobia inoculation (yes or no) on Robinia pseudoacacia (black locust) seedlings supplied with 15NH415NO3. Seedling and nodule growth, nitrogen (N) content, and δ15N × 1000 were evaluated after 3 months. While addition of biochar without inoculation had no effect on seedling growth, inoculation with rhizobia increased seedling growth, BNF, and N status. Inoculated seedlings had reduced δ15N, indicating that N provided via fertilization was being diluted by N additions through BNF. Biochar type and inoculation interacted to affect seedling growth. Combining inoculation with either biochar type increased seedling leaf, stem, and total biomass, whereas gasifier biochar and inoculation improved all seedling growth variables and nodule biomass. [ABSTRACT FROM AUTHOR]

The adsorption potential and governing mechanisms of emerging contaminants, i.e. acetaminophen or acetyl-para-aminophenol (APAP) and methylene blue (MB) dye, on activated carbon derived from municipal solid waste were investigated in this work. Results showed that MB adsorption was significantly more effective, with a maximum removal of 99.9%, than APAP adsorption (%R max  = 63.7%). MB adsorption was found to be unaffected by pH change, while the adsorption capacity of APAP drastically dropped by about 89% when the pH was adjusted from pH 2 to 12. Surface reactions during APAP adsorption was dominated by both physical and chemical interactions, with the kinetic data showing good fit in both pseudo-first order (R 2  = 0.986-0.997) and pseudo-second order (R 2 >0.998) models. On the other hand, MB adsorption was best described by the pseudo-second order model, with R 2 >0.981, denoting that chemisorption controlled the process. Electrostatic attractions and chemical reactions with oxygenated surface functional groups (i.e., -OH and -COOH) govern the adsorption of APAP and MB on the activated biochar. Thermodynamic study showed that APAP and MB adsorption were endothermic with positive ΔH° values of 16.5 and 74.7 kJ mol -1 , respectively. Negative ΔG° values obtained for APAP (-3.7 to -5.1 kJ mol -1 ) and MB (-11.4 to -17.1 kJ mol -1 ) implied that the adsorption onto the activated biochar was spontaneous and feasible. Overall, the study demonstrates the effectiveness of activated biochar from municipal solid wastes as alternative adsorbent for the removal of acetaminophen and methylene blue dye from contaminated waters., (Copyright © 2018 Elsevier Ltd. All rights reserved.)