CO2 dual roles in food scraps-derived biochar activation to enhance lead adsorption capacity

Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO32−) and phosphate (PO43−) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb2+ adsorption sites (CO3...

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Bibliographic Details
Published in:The Science of the total environment 2021-08, Vol.784, p.147218-147218, Article 147218
Main Authors: Wang, Qi, Yu, Fengbo, Zhang, Meilan, Miao, Chunxia, Zhang, Shicheng, Zhu, Xiangdong
Format: Article
Language:English
Subjects:
Biochar
Food scraps
Hydrogel
Pb adsorption
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Summary:Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO32−) and phosphate (PO43−) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb2+ adsorption sites (CO32− and PO43−) of biochar were adjusted by carrier gas atmosphere and activation temperature. Results indicate that CO2 has dual roles in activation of food scraps-derived biochar. CO2 can not only inhibit the decomposition of CO32− but also increase the content of PO43− via consuming aromatic carbon combined with phosphorus at high temperature (>600 °C). Thus, the biochar prepared at 700 °C and CO2 atmosphere has more adsorption sites, resulting in an outstanding Pb adsorption capacity (up to 555.6 mg/g) via coprecipitation mechanisms. As-prepared biochar sample also can be prepared to a hydrogel with a remarkable mechanic strength. But biochar hydrogel decreases Pb adsorption capacity to 104.2 mg/g due to the pore blocking effect. Life cycle assessment illustrates that the scene of food scraps activated by CO2 has lower Global Warming Potential (GWP) and Primary Energy Demand (PED). Therefore, current research provides a high-efficiency method for treatment of food scraps. [Display omitted] •CO2 carrier gas inhibit CO32− decomposition in food scarps (FS) based biochar.•CO2 carrier gas increase PO43− in FS based biochar by consuming aromatic carbon.•Coprecipitation results in biochar with high Pb adsorption capacity (555.6 mg/g).•Hydrogel synthesized by FS based biochar has outstanding mechanical strength.•LCA confirm FS based biochar synthesis in CO2 atmosphere is environmental-friendly.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2021.147218