Immobilization of heavy metals in biochar by co-pyrolysis of sludge and CaSiO3

Zhang, Shijie; Gu, Weihua; Geng, Zhixin; Bai, Jianfeng; Dong, Bin; Zhao, Jing; Zhuang, Xuning; Shih, Kaimin

doi:10.1016/j.jenvman.2022.116635

Cited by 15 publications

(3 citation statements)

References 55 publications

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“…However, the contents of Cu in the FSC were found to be lower compared with that in the FS, indicating that a certain proportion of volatile Cu compounds generated and transferred to bio-oil and bio-gas. This is consistent with the previous study, in which dissatisfactory immobilization rates of Cu (33.62-67.85%) were achieved after the pyrolysis of electroplating sludge [31]. A similar change trend of HM contents could be observed in the co-pyrolyzed biochars, but the concentrations of HM in the SPC were much lower than those in the FSC, which may be attributed to the "dilution effect" caused by the HMs-free PP addition.…”

Section: The Total Contents Of Hms In the Biocharssupporting

confidence: 91%

“…It should be noted that the pH of FS-based biochar was acidic, which is different from that of organic-dominated sludge in the previous studies [30]. One possible reason for these results is that more metal chlorides were produced during the pyrolysis of FS, contributing to the surface acidity of biochars [31]. Comparing with acidic FSC, the addition of PP resulted in a significant elevation of pH, and all the SPCs were alkaline, which is likely induced by the alkaline species such as metal carbonates and hydroxides in the PP.…”

Section: Elemental Analysis and Specific Surface Areamentioning

confidence: 58%

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Co-Pyrolysis of Fenton Sludge and Pomelo Peel for Heavy Metal Stabilization: Speciation Mechanism and Risk Evaluation

Huang,

Wang,

Fan

et al. 2023

Water

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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.

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Section: The Total Contents Of Hms In the Biocharssupporting

confidence: 91%

Section: Elemental Analysis and Specific Surface Areamentioning

confidence: 58%

Co-Pyrolysis of Fenton Sludge and Pomelo Peel for Heavy Metal Stabilization: Speciation Mechanism and Risk Evaluation

Huang,

Wang,

Fan

et al. 2023

Water

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show abstract

“…Studies have demonstrated variability in the bioavailability of diverse forms of HMs. Among these, F1 and F2 were relatively unstable, highly bioavailable, and easily leached, whereas F3 and F4 exhibited relative stability and low bioavailability [ 28 ]. In addition, the risk assessment code ( RAC ) for HMs is often used to assess the environmental impact of F1 forms in sludge biochar.…”

Section: Methodsmentioning

confidence: 99%

Modulatory Role of Biochar Properties and Environmental Risk of Heavy Metals by Co-Pyrolysis of Fenton Sludge and Biochemical Sludge

Li,

Kang,

Wang

et al. 2024

Toxics

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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.

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A systematic review on the bioremediation of metal contaminated soils using biochar and slag: current status and future outlook

Mehmood

Zhang

Alatalo

et al. 2023

Environ Monit Assess

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Immobilization of heavy metals in biochar by co-pyrolysis of sludge and CaSiO3

Cited by 15 publications

References 55 publications

Co-Pyrolysis of Fenton Sludge and Pomelo Peel for Heavy Metal Stabilization: Speciation Mechanism and Risk Evaluation

Co-Pyrolysis of Fenton Sludge and Pomelo Peel for Heavy Metal Stabilization: Speciation Mechanism and Risk Evaluation

Modulatory Role of Biochar Properties and Environmental Risk of Heavy Metals by Co-Pyrolysis of Fenton Sludge and Biochemical Sludge

A systematic review on the bioremediation of metal contaminated soils using biochar and slag: current status and future outlook

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