摘要
A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D)was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and static adsorption experiments.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol(2,4-DCP)mixture or using an aqueous 2,4-D and 2,4-dichlorophenylacetic acid(DPAC)mixture.The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18,the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9.The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent.The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D,73%of binding capacity(200 mg/L 2,4-D onto 20 mg of imprinted sorbent)was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HC1(V:V=1:1).In a test of five extraction/stripping cycles,the adsorption capacity of the sorbent was all above 93%of that of the fresh sorbent.Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.
基金
supported by the Natural Science Foundation of Zhejiang Province(No.Y505073)
the Scientific Project of Zhejiang Province(No.2008C22012)
