关键词: 麦草秸秆, 硝酸根, 吸附, 最大吸附量, 拉曼光谱

Abstract: An anion exchange resin(MWS,modified wheat straw) was prepared by chemical modification of wheat straw grafting epichlorohydrin,triethylamine and diethylenetriamine to improve MWS performance,particularly for adsorption of NO^-₃ in water.The results showed that amine groups with positive-charge had been introduced into the structure of MWS,which resulted in improving significantly adsorption capacity for NO^-₃ in water.The analysis of zeta potential and surface elemental as well as FTIR and Raman spectra indicated that the adsorption mechanism of MWS for NO^-₃ was ion exchange.The adsorption data could be well fitted with the Langmuir model and the correlation coefficient(R²) was higher than 0.988.The results of competition adsorption indicated that the adsorption efficiency for co-present ions followed an order as SO^2-₄>H₂PO^-₄>NO^-₃>NO^-₂.The maximum adsorption capacity(Q_max) of MWS for NO^-₃ was 52.1 mg·g^-1,which could compared with that of commercial resin,and showed that there was a significant increase than that of raw WS(1.3 mg·g^-1).In addition,column adsorption test showed that the breakthrough adsorption capacity for NO^-₃ was about 45.2 mg·g^-1,and both 0.1 mol·L^-1 NaCl and HCl solutions could be used as regenerating agent for the desorption of NO^-₃ from the MWS.

Key words: wheat straw, nitrate, adsorption, maximum adsorption capacity, Raman spectrum