镧铝/壳聚糖复合小球对水中磷的吸附及机理

Adsorption and mechanism of phosphorus in water by lanthanum-aluminum/chitosan composite pellets

镧铝复合材料对水体中磷有着优良的吸附性能,但其粉末状特性大大限制了其应用前景。利用壳聚糖的可塑性,制备出镧铝/壳聚糖复合小球,并利用环氧氯丙烷和聚乙烯醇提高复合材料的耐酸性,同时研究其对水体中磷的静态批吸附及动态柱吸附行为,最后采用SEM、EDS、XRD和FTIR表征方法观察吸附磷前后的微观结构,阐述吸附机理。结果表明:镧铝/壳聚糖复合小球对磷的最大吸附量达到39.84 mg·g^(-1);壳聚糖/镧铝质量比为1/10时,复合小球穿透吸附效率随流速提高而下降,BDST模型能够有效地模拟该复合小球对磷的动态吸附过程;壳聚糖/镧铝质量比为1/4的聚乙烯醇改性复合小球较质量比为1/5的更加耐受水流冲击,吸附效果较为稳定;静电作用,离子交换作用,络合作用和La化合物产生的氧空位是镧铝/壳聚糖复合小球吸磷的主要机理。

Lanthanum aluminum composites show excellent adsorption properties of phosphorus in water, but its application is greatly restricted in powder state. This research investigated the static-adsorption and dynamic-adsorption study of phosphorus removal using lanthanum-aluminum/chitosan composite pellets which were prepared by chitosan,also its acid resistance was improved using epoxy chloropropane and polyvinyl alcohol. Furthermore, SEM, EDS, XRD and FTIR were used to demonstrate its mechanism. The maximum adsorption capacity of lanthanum-aluminum/chitosan composite pellets reached 39.84 mg·g^（-1）.Penetration efficiency of composite pellets decreased with the increase of velocity at the quality ratio of lanthanum-aluminum/chitosan 1/10, showing the dynamic adsorption of phosphorus fit BDST model effectively. Poly（vinyl alcohol） modified composite pellets, of which the quality ratio of the chitosan/lanthanum was1/4, were more resistant to the impact of water flow with a more stable adsorption effect, than that of 1/5. Electrostatic interaction, ion exchange, complexation, and oxygen defect generated by La compounds were the main mechanisms of phosphorus absorption by chitosan/barium-aluminum composite pellets.