Effect of Pyrolysis Temperature on Removal Efficiency and Mechanisms of Hg(II), Cd(II), and Pb (II) by Maize Straw Biochar

Xuebo Hu, Ruigang Zhang, Bing Xia, Rongrong Ying, Zhewei Hu, Xu Tao, Hao Yu, Fabao Xiao, Qiaoying Chu, Hongfeng Chen and Jiazhong Qian
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Xuebo Hu: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Ruigang Zhang: School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
Bing Xia: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Rongrong Ying: Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
Zhewei Hu: Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
Xu Tao: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Hao Yu: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Fabao Xiao: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Qiaoying Chu: School of Resource and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
Hongfeng Chen: Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China
Jiazhong Qian: School of Resource and Environmental Engineering, Hefei University of Technology, Hefei 230009, China

Sustainability, 2022, vol. 14, issue 15, 1-16

Abstract: Pyrolysis temperature significantly affects the properties of biochar, which in turn can affect the removal of heavy metal ions and the underlying mechanism. In this work, biochars from the pyrolysis of maize straw at 300, 400, and 500 °C (BC300, BC400, and BC500, respectively) and wheat straw at 400 °C (WBC400) were investigated. The influence of production temperature on the adsorption of Hg 2+ , Cd 2+ , and Pb 2+ by maize straw biochar was investigated by the characterization of the biochars and by adsorption tests. The adsorption capacities of maize and wheat straw biochar were compared in an adsorption experiment. Biochar BC400 showed the best physical and chemical properties and had the largest number of surface functional groups. The pseudo-second-order kinetic model was more suitable for describing the adsorption behavior of metal ions to biochar. The Langmuir model better fit the experimental data. Biochar BC400 had a higher adsorption speed and a stronger adsorption capacity than WBC400. The sorption of Pb 2+ and Hg 2+ to maize straw biochar followed the mechanisms of surface precipitation of carbonates and phosphates and complexation with oxygenated functional groups and delocalized π electrons. The adsorption mechanism for Cd 2+ was similar to those of Hg 2+ and Pb 2+ , but precipitation mainly occurred through the formation of phosphate. In the multi-heavy-metal system, the adsorption of Cd 2+ by BC400 was inhibited by Pb 2+ and Hg 2+ . In summary, BC400 biochar was most suitable for the adsorption effect of heavy metals in aqueous solution.

Keywords: production temperature; biochars; heavy metals; adsorption (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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