用于吸附氟离子的EGDE交联载镧壳聚糖的制备与表征

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。

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

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 conditions,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.