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| Adsorption of ammonium nitrogen by biochars produced from different biomasses |
| Received:August 17, 2017 |
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| KeyWord:biochar;ammonium nitrogen;adsorption isotherm;kinetic adsorption;oxygen-containing functional group |
| Author Name | Affiliation | E-mail | | SONG Ting-ting | College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | LAI Xin | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | WANG Zhi-wen | College of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | FANG Ming | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | YANG Dian-lin | College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China | | | JU Xue-hai | Rural Energy & Environment Agency, Ministry of Agriculture, Beijing 100125, China | | | LI Jie | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | lijie@caas.cn | | ZHANG Gui-long | College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | zgl-2008@126.com |
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| Abstract: |
| In order to study the effects of different biomasses on the adsorption capacity of ammonium and the adsorption mechanism, peanut shell, maize straw, aspen chips, and bamboo chips were used in the preparation of biochars through N2 protection pyrolysis at 500℃. The biochar adsorption mechanism of NH4+-N was explored via batch equilibrium adsorption test, SEM, and FTIR. The results showed that the surfaces of the four biochars were filled with particles or powders and the pores were filled, which demonstrated that the surface of biochars could be flattened after adsorption of ammonium. Functional groups, such as -OH, -C=O, and -C-O, were distributed on the surface of the different biochars, and the -CH3, -CH2, and -O-groups that distributed on the biochar prepared from peanut shell and maize straw were all involved in their adsorption process. The Langmuir equation could be better fitted to the NH4+-N isothermal adsorption of the four kinds of biochars; the pseudo-second-order kinetics equation could more effectively describe the NH4+-N kinetic adsorption, and equilibrium could be achieved in 50 min. Under the condition of pH=7.00, the adsorption capacity of different biochars reached equilibrium with the initial concentration of 800 mg·L-1, and the maximum adsorption capacity of the biochars varied from 9.5 to 15 mg·g-1. The adsorption capacity of the biochars followed peanut shell > maize straw > aspen chips > bamboo chips. Our main findings are as follows:oxygen-containing functional groups might play a decisive role in enhancing the adsorption capacity; adsorption was of the single molecular layer type; adsorption was controlled by rapid reactions; and peanut shell showed the highest adsorption. |
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