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Effects of freeze-thaw cycles on ammonium-nitrogen adsorption of yak dung biochar
Received:August 01, 2016  
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KeyWord:biochar;freeze-thaw cycles;ammonium;isotherm adsorption;kinetics adsorption
Author NameAffiliationE-mail
WANG Yan-ru The Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China 
 
HOU Jie-fa The Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China 
 
GUO Jian-hua Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China  
HUANG Bing The Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China  
LUO Zhuan-xi Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China zxluo@iue.ac.cn 
CHEN Liang The Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China  
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Abstract:
      In order to understand the effects of freeze-thaw cycles on ammonium-nitrogen(AN) adsorption of yak dung biochar, adsorption batch experiments were conducted to investigate AN adsorption process of different yak dung biochars at different pyrolysis temperature and its freeze-thaw cycles counterparts. Then their physicochemical properties were characterized using elemental analysis, scanning electron microscopy, FTIR spectra, and BET-N2 surface area(SSA) to explore the adsorption mechanism of AN by freeze-thaw cycles biochars. Results showed that the AN adsorption kinetics of yak dung biochars fitted the pseudo-second-order model, and AN adsorption isotherms were fitted the Freundlich model. There were significant differences in AN adsorption onto yak dung biochars at different pyrolysis temperature.More effective roles were observed to be played on AN adsorption by yak dung biochars at higher pyrolysis temperature by freeze-thaw cycle(C0<20 mg·L-1). Ammonium adsorption onto of PBC450 and PBC600(biochars with freeze-thaw cycles at 450℃ and 600℃, respectively) were remarkably increased 13.1%, 12.4%, and the AN removal rate were reached 62.6% and 55%(C0=5 mg·L-1). After freeze-thaw cycles, the cation exchange capacity(CEC) and SSA of PBC450 and PBC600 remarkably increased, the CEC increased 9.1% and 75.7%, while the pH and Zeta potential remarkably decreased. Herein, the CEC and SSA were the main influenced factors in the AN adsorption.