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| Adsorption characteristics of Cd2+ and Pb2+ on biochar/attapulgite composites |
| Received:August 05, 2022 |
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| KeyWord:biochar;attapulgite;heavy metal;adsorption;quantitative analysis |
| Author Name | Affiliation | E-mail | | LI Beibei | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China
Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210042, China | | | ZHANG Yaping | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | amflora@126.com | | GUO Bingyue | Geological Exploration Technology Institute of Jiangsu Province, Nanjing 210008, China | | | YANG Kunpeng | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | | | SHEN Kai | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | | | HU Wenyou | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210042, China | |
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| Abstract: |
| A novel low-cost biochar/attapulgite composite material was prepared by pyrolysis under anoxic conditions with different proportions of rice straw, wheat straw, and attapulgite. Batch adsorption experiments were conducted to investigate the effects of adsorption time, initial concentration, and pH on the adsorption efficiency of Cd2+ and Pb2+. SEM, BET, XRD, and FTIR were used to characterize the composite materials before and after adsorption, and the adsorption mechanisms were studied from qualitative and quantitative perspectives. The results showed that the Pseudo-second-order kinetic model and the Langmuir isotherm model could describe the Cd 2+ and Pb2+ adsorption processes of the composites better. Compared with the original biochar and attapulgite, the composites RABC5-1(the ratio of rice straw to attapulgite was 5:1) and WABC3-1(the ratio of wheat straw to attapulgite was 3:1) showed better adsorption performance. The maximum adsorption capacities for Cd2+ were 132.97 mg·g-1 and 132.39 mg·g-1; for Pb2+, they were 222.60 mg·g-1 and 220.55 mg · g-1, respectively. The quantitative analysis revealed that precipitation was calculated to be 84.6% and 77.3% in the Cd2+ adsorption, 82.0% and 78.3% in the Pb2+ adsorption by RABC5-1 and WABC3-1, respectively, which was the main mechanism for heavy metal adsorption by composite materials, followed by cation exchange, functional group complexation, and cation-π interaction, which contributed less to the overall adsorption. The study demonstrates that the composites RABC5-1 and WABC3-1 have great adsorption properties for Cd2+ and Pb2+ and are potential adsorption materials. The mechanism analysis also reveal that precipitation is the dominant mechanism for the adsorption of heavy metals by the composites. |
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