硫脲改性磁性壳聚糖微球对Hg~(2+)的吸附特性

利用悬浮分散以及化学交联技术制备磁性壳聚糖微球,并经硫脲改性(SMCS),用于吸附水溶液中Hg2+。用光学显微图、红外、热重分析等对微球进行了表征;考察了pH值、Hg2+初始浓度、吸附时间以及振荡速率对Hg2+吸附的影响。结果表明,SMCS为球形,粒径50—80μm。SMCS对Hg2+有良好的吸附性能,饱和吸附容量(1.2—6.5 mmol/g)随pH值升高而增加,pH值为5.0时饱和吸附容量约为2.9 mmol/g。等温吸附线可用Freundlich等式拟合。吸附动力学结果表明,振荡速率为150—200 r/min时,为内扩散控制;50—150 r/min时,由外扩散和内扩散同时控制;振荡速率<<50 r/min时,为外扩散控制。吸附动力学可用拟二级模型拟合,初始吸附速率为0.22—1.77 mmol/(g.h),随振荡速率加快而增加。

Adsorption characteristics of Hg2+ by thiourea-modified magnetic chitosan microspheres

The magnetic chitosan microspheres were prepared by inverse phase suspension cross-linking technique and modified with thiourea as an adsorbent for Hg2+ removal from the aqueous solution.This adsorbent was characterized by optical micrographs,FTIR,TGA,etc.The effects of pH values,Hg2+ initial concentration,adsorption time and stirring rates on the Hg2+ adsorption by thiourea-modified magnetic chitosan(TMCS) were investigated.The results show that TMCS has a spherical shape with a diameter of 50-80 μm and excellent performance for Hg2+ adsorption.The saturated adsorption capacity(1.2-6.5 mmol/g) for Hg2+ increases with the increasing of pH value,and is 2.9 mmol/g at pH=5.0.The adsorption equilibrium data were fitted well by Freundlich isotherms.The results of uptake kinetics indicate that the adsorption is controlled by internal diffusion at agitation rates of 150-200 r/min,but by both internal diffusion and external diffusion at 50-150 r/min,and by external diffusion at<<50 r/min.The pseudo-second order is suitable to describe the kinetic process of Hg2+ adsorption onto the adsorbent.The initial adsorption rate is 0.22-1.77 mmol/(g·h),which increases with increasing agitation rate.