磁性环氧丙基三甲基氯化铵-β-环糊精复合水凝胶对草甘膦的吸附性能

Adsorption performance of magnetic glycidyl trimethyl ammonium chloride-β-cyclodextrin composite hydrogel toward glyphosate

为有效去除水中的草甘膦,合成了一种磁性环氧丙基三甲基氯化铵-β-环糊精复合水凝胶(MGTACDCH),且对其进行了结构表征,探究了溶液初始pH、草甘膦浓度等对MGTA-CDCH吸附性能的影响。结果表明:在pH=3~10.5时,MGTA-CDCH的Zeta电位均能够保持在27 mV以上;MGTA-CDCH对草甘膦的吸附过程符合Sips等温线模型,饱和吸附量为179.2 mg·g-1,且在1 h内可达到饱和吸附容量的96.6%;由于草甘膦属于阴离子有机物,MGTA-CDCH中季胺基团和羟基基团可以与其发生静电和氢键作用,因此,溶液pH对吸附作用影响较大,pH=3~7为吸附的适用范围,此后,随着pH的升高,MGTA-CDCH对草甘膦的吸附量明显下降。此外,腐殖酸对MGTA-CDCH吸附草甘膦存在较为明显的抑制效果,但抑制效果随着腐殖酸浓度的升高而减弱;MGTA-CDCH在5次循环再生后仍能保持86%的吸附容量。上述研究结果表明,MGTA-CDCH在含草甘膦废水处理中具有潜在的应用价值。

In order to effectively remove glyphosate, a magnetic glycidyl trimethyl ammonium chloride-β-cyclodextrin composite hydrogel(MGTA-CDCH) was prepared. In combination of MGTA-CDCH characterization, the effects of initial pH, glyphosate concentration in water on the MGTA-CDCH adsorption performance were studied. The results showed that the zeta-potential of MGTA-CDCH maintained above 27 mV within pH range of 3.0~10.5. The adsorption process of glyphosate by MGTA-CDCH fitted the Sips model, and the corresponding saturated adsorption capacity was 179.2 mg·g-1, and the adsorption amount of glyphosate could reach 96.6% of this capacity within 1 h. As a type of anionic organic matter, the quaternary amine groups and the hydroxyl groups in MGTA-CDCH could attracted glyphosate through electrostatic interactions and hydrogen bonding, respectively, thus the solution pH had a significant effect on the adsorption of glyphosate on MGTA-CDCH, the feasible pH range was 3~7. Afterwards, the adsorption amount of glyphosate on MGTACDCH decreased drastically with the increase of pH. In addition, humic acid could inhibit the glyphosate adsorption on MGTA-CDCH, but the inhibitory effect weakened with the increase of humic acid concentration.After five regeneration-reuse cycles, its residual adsorption capacity still maintained 86% of fresh MGTACDCH. Above all, this study indicates that MGTA-CDCH has potential application in glyphosate wastewater treatment.