没食子酸修饰的超高交联吸附树脂对2,4-二氯苯氧乙酸的吸附性能研究

Adsorption properties investigation of 2,4-dichlorophenoxyacetic acid onto gallic acid modified hyper-cross-linked resin

通过后交联反应和化学修饰反应制备了没食子酸修饰的超高交联吸附树脂(GAMR),以大孔吸附树脂XAD-4树脂为对照,研究了GAMR对水中2,4-二氯苯氧乙酸(2,4-D)的吸附性能.实验结果表明:GAMR具有较丰富的微孔,比表面积和微孔面积分别为1 232.3和899.5 m2·g-1.GAMR对2,4-D的吸附动力学过程符合准一级动力学方程,吸附过程同时存在物理吸附和化学吸附.Freundlich等温方程能较好地拟合GAMR对2,4-D的吸附等温线.GAMR对2,4-D吸附过程的ΔG为负值,ΔH和ΔS均大于0,表明吸附是自发、吸热和熵增加的过程.与XAD-4相比,所制备的GAMR对2,4-D的吸附去除率显著提高.

A new hyper-cross-linked resin GAMR was prepared by post-crosslinking of chloromethyl low crosslinking poly-styrene and chemically modifying with gallic acid. The adsorption properties of GAMR for 2,4-dichlorophenoxyacetic acid(2,4-D) in aqueous solution were investigated as compared with XAD-4 resin. The results indicated that GAMR had rich micropore distribution. And the BET surface and micropore areas were 1 232.3 and 899.5 m2·g-1, respectively. The kinetics experiment showed that the adsorption of 2,4-D onto GAMR was in accord with the pseudo first-order kinetic equation. The physical sorption and chemical sorption interaction coexisted in the adsorption process of 2,4-D onto GAMR. Freundlich isothermal adsorption equations could well fit the adsorption isotherms of 2,4-D onto GAMR. The results of thermodynamic calculations of 2,4-D onto GAMR showed that ΔG<0, ΔH>0, and ΔS>0, which indicated that the adsorption was a spontaneous, endothermic process with increased randomness. The adsorption efficiency of 2,4-D by GAMR was enhanced remarkably compared to XAD-4.