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| Adsorption characteristics and mechanisms of Cd2+ in biochar derived from vetiver grass under different pyrolysis temperatures |
| Received:August 03, 2017 Revised:September 27, 2017 |
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| KeyWord:vetiver grass;biochar;cadmium;pyrolysis temperatures;adsorption characteristics |
| Author Name | Affiliation | E-mail | | DENG Jin-huan | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 | | | GAO Li-yang | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 | | | ZHOU Wan-wan | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 | | | DU Wei-ting | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045 | | | CAI Kun-zheng | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642
Key Laboratory of Tropical Agro-Environment, Ministry of Agriculture, Guangzhou 510642 | | | CHEN Gui-kui | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642
Key Laboratory of Tropical Agro-Environment, Ministry of Agriculture, Guangzhou 510642 | | | HUANG Fei | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642
Key Laboratory of Tropical Agro-Environment, Ministry of Agriculture, Guangzhou 510642 | feihuang@scau.edu.cn |
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| Abstract: |
| To explore the adsorption characteristics and mechanisms of Cd2+ in biochar, three biochar samples were prepared by heating vetiver grass(Vetiveria zizanioides L.) under different pyrolysis temperatures of 300, 500℃ and 700℃(BC300, BC500, and BC700) and characterized by elemental analysis, BET-N2 surface area, zeta analysis, scanning electron microscopy with energy dispersive spectroscopy(SEM-EDS), and Fourier-transform infrared spectroscopy(FTIR). Results showed that when the pyrolysis temperature increased, yields decreased; however, the ash content, pH, zeta potential, and specific surface area increased especially for BC700(227.04 m2·g-1), which was 67.8 times higher than that in the raw material. The Freundlich model was more suitable for describing the adsorption processes(R2> 0.98), with the adsorption capacity following a descending order of BC700(92.65 mg·g-1) > BC500(80.17 mg·g-1) > BC300(76.29 mg·g-1). Adsorption kinetics showed that the equilibrium time followed an ascending order of BC700(80 min) < BC500(180 min) < BC300(240 min), which were better fitted by the pseudo-second order model(R2>0.98). SEM-EDS and FTIR analyses indicated that the adsorption mechanisms mainly included surface electrostatic adsorption and complexation. The BC700 sample, which was equipped with a larger specific surface area, and greater amounts of negative charge and functional groups, was more effective than the other biochar samples. These observations suggest that biochars derived from vetiver grass have the potential to treat Cd2+ in wastewater. |
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