Study on Structural Characteristics of Wheat Straw Biochar and Its Adsorption Performance for Cr(Ⅵ)
Two types of wheat straw biochar were prepared under conditions of 300 ℃(WS300)and 500 ℃(WS500),then their physicochemical properties were characterized,and their adsorption characteristics of Cr(Ⅵ)were studied.The results showed that the higher the pyrolysis temperature,the higher the C content and condensation degree of biochar,while the lower the polarity and hydrophilicity.WS500 had a larger specific surface area and pore volume.Cr(Ⅵ)was mainly adsorbed on the surface of biochar in the form of Cr oxides such as HCrO4+or Cr2O72-.WS500 had more abundant functional groups such as hydroxyl,carboxyl and ester groups,which could undergo complexation,redox and other reactions with Cr(Ⅵ).The adsorption isotherm of Cr(Ⅵ)was more suitable for fitting with the Langmuir model,indicating that the adsorption process was mainly monolayer.The adsorption capacity of Cr(Ⅵ)on WS500 was higher than that on WS300.
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