负载镧的EGDE交联壳聚糖微球对氟离子的吸附平衡与吸附动力学

采用负载镧的乙二醇二缩水甘油醚(EGDE)交联壳聚糖微球对含氟水进行吸附处理.该吸附剂的适宜工作条件为:温度30～50℃,pH值7.0,吸附时间30 min.用吸附等温线描述了F-在吸附剂上的吸附平衡,并用动力学模型研究了其吸附动力学机制.结果表明:吸附剂对F-的吸附平衡符合Langmuir吸附等温线和Freundlich吸附等温线,饱和吸附容量为25.7mg·g-1；该吸附剂对F-的吸附既包含化学吸附又包含物理吸附过程,以单分子层的化学吸附为主；吸附动力学符合拟二级动力学方程,吸附过程受化学吸附机理的控制,颗粒内扩散和液膜形成的边界层是其限速步骤.

Adsorption Equilibrium and Kinetics of Fluoride on La( Ⅲ )-Loaded Chitosan Beads Crosslinked by EGDE

The water containing high fluoride ions was treated by the applicability of La(Ⅲ)-loaded chitosan beads crosslinked by ethylene glycol diglycidyl ether(EGDE).The suitable treatment conditions were: temperature was 30~50 ℃,pH value was 7.0,and contact time was 30min.The adsorption equilibrium behavior was described using adsorption isotherms;and several dynamic models were adopted to interpret the adsorption dynamics mechanism.The equilibrium data fitted well both to Langmuir and Freundlich isotherms;the maximum adsorption capacity for F-was 25.7 mg·g-1.It was found that the physical adsorption and the chemical adsorption coexisted;the monomolecular layer chemical adsorption was the dominant type.Adsorption kinetics study revealed that the adsorption process followed pseudo-second-order model;the adsorption process was complex and controlled by chemical adsorption mechanism;both the boundary of liquid film and intraparticle diffusion contributed to the rate-determining step.