用于吸附氟离子的EGDE交联载镧壳聚糖的制备与表征

Preparation and Characterization of EGDE-crosslinked and La-incorporated Chitosan Beads for Defluoridation from Water

利用戊二醛(GLA)交联并负载La3+的壳聚糖吸附净化高氟地下水时,反应不完全的戊二醛可能会溶出而产生较大的生物毒性。选用低毒的乙二醇二缩水甘油醚(EGDE)替代GLA,对壳聚糖实施交联改性,生成交联壳聚糖微球(CEB),然后在CEB表面螯合La3+,制备新型除氟剂(CEB-La)。结果表明,交联温度是影响CEB-La吸附性能的最主要因素,交联的适宜条件为EGDE与CS的-NH2物质的量比为1∶2,20℃反应4h;螯合的适宜条件为将CEB按投加量2g/L加到0.020mol/L的La3+溶液中,40℃反应3h。所得到的吸附剂具有良好的稳定性,对质量浓度20mg/L含氟水的F-去除率达96%。红外光谱分析表明,EGDE与壳聚糖的-NH2、C6-OH发生交联反应,形成的交联产物CEB中,仲羟基与La3+配位。X射线衍射分析表明,壳聚糖微球在制备过程中结晶能力下降,有利于La3+的负载和F-的吸附,除氟剂中的镧主要以La-O化物的形式存在。

A new absorbent to remove fluoride from drinking water was studied using lanthanum incorporated chitosan beads which had been cross-linked with ethylene glycol diglycidyl ether（EGDE） previously substituted of glutaraldehyde（GLA）. The results of orthogonal experiment show that the fluoride removal efficiency of absorbent （CEB-La） is mostly effected by the cross-linking temperature. The synthesis conditions of CEB-La are optimized as follows： chitosan beads are cross-linked with EGDE for 4 hours under the temperature of 20℃ and the molar ratio of EGDE and amino is 1 ： 2; the chelating time is 3 hours under the temperature of 40℃ and the dose of cross-linked chitosan beads（CEB） is 2g/L. Treated the water containing F- of 20mg/L using CEB-La prepared under these condi- tions, the residual concentration of F- was 0. 79mg/L, lower than 1.0mg/L. These absorbents had good stability. The beads were characterized using FT-IR and XRD. The FT-IR spectra indicated that after EGDE reacted with amino and primary hydroxyl groups in chitosan, lanthanum coordinated with second hydroxyl group in CEB. The XRD spectra showed the crystallinity of CEB and CEB-La decreased distinctly which benefits the loading of lanthanum on CEB and fluoride adsorbing to CEB-La. Phase identifying for inorganic component of CEB-La revealed that lanthanum oxi- de was the main form of lanthanum.