石墨烯基铁氧化物对水体中草甘膦的动态吸附性能及模型

Mechanism and model of dynamic adsorption of glyphosate contaminated water on graphene-based iron oxide composite

采用热沉积法制备出石墨烯/四氧化三铁(RGO-Fe_3O_4)复合材料,针对草甘膦(GLY)污染水体,开展该吸附材料对GLY的动态柱实验,通过考察污染物浓度、pH、流速、柱高等因素对穿透过程的影响,研究复合材料对GLY的动态吸附性能,并结合扫描电子显微镜(SEM-EDS)、X射线光电子能谱仪(XPS)、全自动比表面和孔隙分析仪(BET)等表征手段和Thomas、Yoon-Nelson和Yan等吸附模型分析吸附机理。实验结果表明:随着柱高增加,穿透时间延长,吸附柱对GLY的吸附总量增大;随着GLY初始浓度的升高,穿透时间缩短,吸附柱对GLY的吸附总量增大;随着流速和pH的升高,穿透时间缩短,吸附柱对GLY的吸附总量减小。此外,Thomas、Yoon-Nelson和Yan模型拟合得到的R^2均大于0.9,且理论单位吸附量均与实际值相差不大,即3种模型均可较好地描述石墨烯复合材料对GLY的动态吸附过程。本实验的研究对石墨烯材料的推广应用及实际GLY污染水体的修复具有重要意义。

Reduced graphene-based iron oxide composite was prepared via thermal chemical deposition method and used to remove glyphosate(GLY)contaminated water by a dynamic adsorption experiment.Influences of GLY concentration,solution pH,flow rate and filler bed height were analyzed.The dynamic adsorption mechanism was characterized by SEM-EDS,XPS and BET,as well as Thomas,Yoon-Nelson and Yan adsorption models.The results demonstrated that the glyphosate adsorptivity increased and the breakthrough time decreased with the increase of the initial glyphosate concentration,however,breakthrough time prolonged when increasing the adsorbent quality.In contrast,the glyphosate adsorptivity and the breakthrough time decreased with an increase in the pH value and flow rate.The fitting results matched Thomas,Yoon-Nelson and Yan model well,and the theoretical adsorption capacities were in close agreement with the experimental data.To study the dynamic adsorption process and the adsorption microscopic mechanism is of vital theoretical and practical significance for the popularization of graphene materials and the treatment of glyphosate contaminated water.