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| Removal of aqueous Cd(Ⅱ) by biochar derived from rice straw and its anaerobically digested residue |
| Received:September 10, 2017 |
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| KeyWord:rice straw;anaerobic digestion;biochar;Cd(Ⅱ);adsorption |
| Author Name | Affiliation | E-mail | | LI Jin-yang | Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China
State Grid Sichuan Power Economic Research Institute, Chengdu 611130, China | | | GUO Hai-yan | Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | SHEN Fei | Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | fishen@sicau.edu.cn | | DENG Shi-huai | Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | |
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| Abstract: |
| To develop a novel use for rice straw and its anaerobically digested residue, the two resources were carbonized using slow pyrolysis at 500℃ to produce biochar(RS500 and DRS500, respectively). The thermal stability of the two biochars was compared, as well as their main characteristics, including morphology, elemental composition, electrical conductivity, pH, and surface functional groups. Meanwhile, the adsorption of Cd(Ⅱ) by RS500 and DRS500 were investigated, and potential mechanisms for the observed adsorption as well. DRS500 contained relatively higher levels of C, H, and O, but not N, and possessed relatively lower electrical conductivity and surface area. The thermogravimetric(TG) curves indicated that DRS500 had greater thermal stability. The adsorption equilibrium of RS500 was achieved at 12 h, but the DRS500 was hard to achieve the adsorption equilibrium in 48 h. Increasing the solution pH promoted the adsorption of Cd(Ⅱ) by RS500 but reduced the adsorption of Cd(Ⅱ) by DRS500. The adsorption of Cd(Ⅱ) by RS500 and DRS500 can be regarded as an endothermic process because higher temperatures were beneficial to Cd(Ⅱ) adsorption. The Langmuir adsorption isotherms model was suitable for describing the adsorption process, and adsorption kinetics could be simulated well by the second-order model, which indicated that Cd(Ⅱ) adsorption was dominated by chemical adsorption, during which surface functional groups, including -OH, C=O, Si-O-Si, and C-H played key roles in Cd(Ⅱ) removal. |
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