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The removal effect of magnetic biochar on pyrene in aqueous phase
Received:July 16, 2016  
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KeyWord:magnetic biochar;water contamination;polycyclic aromatic hydrocarbons;X-ray diffraction;infrared spectroscopy
Author NameAffiliationE-mail
XI Zhi-nan College of Environmental & Resource Sciences, Shanxi University, Taiyuan 030006, China  
LI Zeng-bo School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030002, China lizengbo@sina.com 
WANG Cong-ying College of Environmental & Resource Sciences, Shanxi University, Taiyuan 030006, China wangcongying@sxu.edu.cn 
SHI Zhi-ming College of Environmental & Resource Sciences, Shanxi University, Taiyuan 030006, China  
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Abstract:
      Biochar has been proved effectively in removing pollutants form aqueous phase. However,powdered biochar,was difficult to be separated from the aqueous solution. Introducing magnetic medium to biochar is an efficient method to separate sorbent effectively from aqueous phase by magnetic separating technique. In the present study,magnetic biochars(LZ1.5 and LZ2.5) were prepared by chemical co-precipitation of iron oxide on willow wood biochar(LZ) which was produced at 600℃. The surface structure,element composition and functional group of biochars were analyzed by the analysis methods of BET-N2 specific surface,fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and powder X-ray diffraction(XRD). The adsorption behavior of pyrene on biochars was studied to verify the removal effect of magnetic biochar on organic pollutants in aqueous phase. Adsorption equilibrium of pyrene on pristine biochar(LZ) and magnetic biochars were obtained at 24 h and 72 h,respectively. Both the Langmuir and Freundlich equations fit the isothermal data well(P<0.05). LZ1.5 showed the best adsorption capacity,with the maximum adsorption capacity of 2 758.62 μg·g-1,followed by LZ2.5(833.3 μg·g-1) and LZ(322.6 μg·g-1). 90% of pyrene was removed when LZ1.5 was added at the dose of 375 mg·L-1. The results suggested that the magnetic biochar was a promising sorbent for removing organic pollutants from wastewater. The enhanced adsorption of pyrene was partly due to the original aromatic functional groups. Additionally,the increased micropore structure and the hydroxylation of the magnetic biochar surface by introducing Fe3O4 were also contributed to the adsorption.