Influence of pyrolysis temperature on chemical speciation, leaching ability, and environmental risk of heavy metals in biochar derived from cow manure

•Biochar were obtained from cow manure under different pyrolysis temperatures.•Heavy metals were mostly enriched in biochar during pyrolysis.•The heavy metals were transformed from the bioavailable to stable fractions.•Leaching ability of heavy metals were effected by pH and pyrolysis temperatures.•...

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Bibliographic Details
Published in:Bioresource technology 2020-04, Vol.302, p.122850-122850, Article 122850
Main Authors: Zhang, Peizhen, Zhang, Xiaoxiao, Li, Yanfei, Han, Lujia
Format: Article
Language:English
Subjects:
Animals
Cattle
Charcoal
Chemical speciation
China
Cow manure biochar
Environmental Monitoring
Female
Heavy metal
Manure
Metals, Heavy
Pyrolysis
Pyrolysis temperature
Risk Assessment
Temperature
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Summary:•Biochar were obtained from cow manure under different pyrolysis temperatures.•Heavy metals were mostly enriched in biochar during pyrolysis.•The heavy metals were transformed from the bioavailable to stable fractions.•Leaching ability of heavy metals were effected by pH and pyrolysis temperatures.•The potential environmental risk and eco-toxicity of heavy metals were relieved. This study analyzed the chemical speciation, leaching ability, and environmental risk of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in cow manure biochar (CMBC) pyrolyzed at various temperatures. The total content, chemical speciation, and leaching ability of the heavy metals were determined through microwave digestion, modified BCR three-step sequential extraction procedure, and leaching solution systems (TCLP, distilled water, and SPLP). The risk assessment code, Muller geo-accumulation index, potential ecological risk index, and germination index were used to evaluate the environmental safety and ecotoxicity of heavy metals. Significant differences were observed in the physicochemical properties of CMBCs. The heavy metal contents in CMBCs were higher than those in CM. The bioavailable fraction of heavy metals was transformed into a relatively stable fraction with increasing pyrolysis temperature. Furthermore, the potential risks and ecotoxicity of biochar were reduced, thus improving environmental safety. The study results provide important data for biochar applications.
ISSN:0960-8524
1873-2976
DOI:10.1016/j.biortech.2020.122850