天然沸石负载壳聚糖吸附溶液中镉(Ⅱ)的研究

Adsorption of cadmium (Ⅱ) in solution by natural zeolite-chitosan adsorbent

根据天然沸石的离子交换特性,利用壳聚糖在酸性溶液中带有的正电荷,将80目天然沸石与90%脱乙酰度壳聚糖的0.5%醋酸溶液混合,使壳聚糖负载在天然沸石上,制成颗粒吸附剂,用于吸附溶液中的Cd^2＋。结果表明,在最佳吸附条件下,即壳聚糖与天然沸石质量比为1∶20,颗粒吸附剂用量为15g/L,溶液中Cd^2＋质量浓度不大于300mg/L,pH=6~8,吸附平衡时间为8h,Cd^2＋的吸附率为99%。本文结果为利用天然沸石原位修复镉污染土壤提供了理论依据。

This paper is inclined to present the study on the way to improve the natural zeolite adsorbent ability for cadmium （ Ⅱ ） in the solution prepared with the combination of chitosan and zeolite. Since the interchangeability is characteristic of natural zeolite ions, chitosan would be positive in charge in the acid solution. Based on the two properties mentioned above, we can add 80 mesh natural zeolites to the 90% of chitosan slurry in the 0.5% of deacetylation to prepare adsorbent. The optimal conditions for absorption can be listed as follows ： the mass ratio of chitosan to natural zeolite is 1 ： 20, while the dosage of the adsorbent is 15 g/L. If the mass concentration of Cd （ Ⅱ ） in the wastewater is no more than 300 mg/L, the pH value should be controlled between 6 - 8. And, when the adsorption equilibrium time is nearly 8 h, the Cd （ Ⅱ ） removal efficiency should reach 99 %. The above said method and the activated carbon absorbing method may demonstrate a similar effect. However, since the former has a lower cost, that is, only 1/6 of the latter, this absorbent may have a stronger absorbability, as well as a lower cost, as compared with the single natural zeolite or single chitosan. Also, the results would provide a theoretical basis for utilizing natural zeolite to extract heavy metals from the contaminated soils.