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| Adsorption and interaction of Cd(Ⅱ) and pyrene in water on walnut shell biochar |
| Received:February 24, 2017 |
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| KeyWord:walnut shell biochar;cadmium(Ⅱ);pyrene;sorption;interaction |
| Author Name | Affiliation | E-mail | | WANG Li-guo | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | | | ZHONG Jin-kui | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | zhongjk@mail.lzjtu.cn | | ZHAO Bao-wei | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | | | ZHANG Jian-yu | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | | | LI Liu | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | | | YANG Qiao-zhen | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | | | CHEN Wei-yi | School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China | |
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| Abstract: |
| The walnut shell biochar(WSBC) used in this study was made via pyrolysis of walnut shell at 600℃. Using Scanning Electron Microscopy(SEM) and Fourier Transform Infrared Spectroscopy(FTIR), the surface structure and functional groups of the WSBC were characterized. The sorption behaviors of Cd(Ⅱ) and pyrene in single and binary systems were investigated. Batch sorption experiments of the kinetics and isotherms for the WSBC were performed under different temperature, contact time, initial concentration of Cd(Ⅱ) and pyrene, and pH of aqueous solutions. The experimental data show that the WSBC contains an aromatic and a heterocyclic and has a coarse surface. Its porous structure is significant, and hydroxyl, carboxyl, carbonyl, and other oxygen-containing functional groups at the surface of the WSBC are abundant. Batch sorption experimental results show that the achieved equilibrium times were 20 h and 16 h for Cd(Ⅱ) and pyrene, respectively, and the saturated adsorption capacities were 23.79 mg·g-1 and 0.17 mg·g-1. It was found that the sorption was best described by the pseudo-second-order kinetic model. Two sorption isotherms were tested to fit the monocomponent equilibrium data, with the best description obtained using the Langmuir-type isotherm model. The individual sorption for Cd(Ⅱ) or pyrene was influenced by pH. For Cd(Ⅱ), the WSBC exhibited the maximal sorption capacity at pH 5. As for pyrene, the adsorption capacity increased with a decrease of pH in the pH range of 3 to 11. The sorption of both Cd(Ⅱ) and pyrene by WSBC depended on WSBC particle size, i.e., WSBC with smaller particle size had a better adsorption capacity for both Cd(Ⅱ) and pyrene. The results also show that the sorption capacity of Cd(Ⅱ) onto WSBC is influenced by the presence of pyrene, and vice versa; thus, there is competition between Cd(Ⅱ) and pyrene for sorption sites. These observations provide a reference for the use of WSBC as an engineered sorbent for environmental applications. |
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