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Optimization, characterization, and Cr(Ⅵ)adsorption properties of iron oxide-coated wheat straw biochar
Received:January 03, 2019  
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KeyWord:wheat straw biochar;iron oxide;adsorption;chromium(Ⅵ);response surface methodology
Author NameAffiliationE-mail
LI Ji-hui Linyi Academy of Agricultural Sciences, Linyi 276012, China  
WANG Peng Linyi Academy of Agricultural Sciences, Linyi 276012, China  
ZHUANG Ke-zhang Linyi Academy of Agricultural Sciences, Linyi 276012, China  
BIAN Jian-bo Linyi Academy of Agricultural Sciences, Linyi 276012, China  
TANG Hong-jie Linyi Academy of Agricultural Sciences, Linyi 276012, China  
GUO Yan-ping Linyi Academy of Agricultural Sciences, Linyi 276012, China  
SONG Ji-qing Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China songjiqing@caas.cn 
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Abstract:
      To enhance the adsorption capacity of chromium (Ⅵ) from water by wheat straw biochar, FeCl3 solution was used to introduce iron oxide into the biochar pores; the preparation process was optimized using response surface methodology (RSM). A carbonization temperature of 400℃ and iron/biochar mass ratio of 0.85 were the optimum conditions for the preparation of iron oxide-modified straw biochar (expressed as optimal modified biochar). The optimal modified biochar and the straw biochar samples were characterized by elemental analysis, BET specific surface area, scanning electron microscopy, infrared spectroscopy, and X-ray diffraction. The surface of the optimal modified biochar was rough, the specific surface area and pore volume increased, and a large amount of iron oxide was introduced into the biochar pores. The chromium adsorption performance results showed that the maximum chromium adsorption capacity was 30.96 mg·g-1, based on Langmuir theory. Kinetic studies showed that a pseudo second-order rate equation fit the experimental data well. Chromium adsorption decreased with an increase in pH. With an increase in straw biochar content, the removal rate of chromium increased. The adsorption ability of wheat straw biochar was significantly improved with iron oxide coating, which can be used for the adsorption removal of Cr (Ⅵ) from water, providing a new way to use crop straw efficiently.