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| Adsorption of Pb2+ and Cd2+ in Aqueous Solution by Biochars Derived from Different Crop Residues |
| Received:November 07, 2014 |
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| KeyWord:crop residue;biochar;Pb2+;Cd2+;adsorption |
| Author Name | Affiliation | E-mail | | LI Rui-yue | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | | | CHEN De | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | | | LI Lian-qing | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | lqli@njau.edu.cn | | PAN Gen-xing | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | | | CHEN Jian-qing | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | | | GUO Hu | Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China | |
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| Abstract: |
| Three kinds of crop residues, including wheat straw, rice straw, and maize stalk, were used to generate biochars at pyrolysis temperature of 450 ℃。 The biochars obtained were employed to study Pb2+ and Cd2+ adsorption. Results showed that the sorption kinetics of Pb2+ and Cd2+ on biochar particles followed pseudo second order kinetic model. The adsorption rates of Pb2+ by wheat straw biochar(WSB), rice straw biochar(RSB) and maize stalk biochar(MSB) were 0.044, 0.019 and 0.012 mg·g-1·h-1 and 0.195, 0.164 and 0.070 mg·g-1·h-1 for Cd2+, respectively. Isothermal adsorption of Pb2+ and Cd2+ by WSB, RSB and MSB fitted well with Langmuir equation. The maximum sorption capacity of Pb2+ by WSB, RSB and MSB was 99.65, 110.31 and 88.82 mg·g-1, and 30.64, 29.39, and 21.47 mg·g-1 for Cd2+, respectively. The removal rates of metals from solution increased dramatically when the initial pH increased from 2.5 to 3.5. The removal mechanism of Pb2+ and Cd2+ from aqueous solution might be chemical precipitation with CO32-, CO43-, SiO2 in WSB and RSB, while through adsorption on the surface of MSB particles with high amount of functional groups. |
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