质子化交联壳聚糖对水中高氯酸根的吸附特性研究

通过合成质子化交联壳聚糖,采用静态试验方法对水中高氯酸根(ClO4-)的吸附效果及机制进行了研究,考察了pH、温度和初始浓度对吸附过程的影响以及吸附剂的重复使用性能.结果表明,质子化交联壳聚糖吸附ClO4-过程属放热反应;当pH在3.0~6.0之间时,对ClO4-均有较好的吸附作用;随着ClO4-初始浓度的增加,吸附容量增加,当初始浓度为100 mg.L-1时,吸附容量在34.39~37.98 mg.g-1之间;当ClO4-为400 mg.L-1时,吸附容量达128.78 mg.g-1.质子化交联壳聚糖对水中ClO4-的吸附过程符合Langmuir和Freundlich等温吸附模型,ClO4-在质子化交联壳聚糖小球上的吸附过程中化学吸附为速率控制步骤.质子化交联壳聚糖小球可在pH为12.8的NaOH溶液中再生,反复使用10次其吸附容量无明显变化,表现出较好的吸附/解吸性能,这为有效地去除水中的ClO4-提供了新的方法.

Adsorption of Perchlorate from Water by Protonated Cross-linked Chitosan Gel Beads

Cross-linked chitosan gel beads were used to adsorb perchlorate (ClO^-₄) from water. Batch experiments were conducted to investigate the effects of temperature, pH, and initial ClO^-₄ concentration, adsorption isotherms and kinetics, and regeneration ability. The adsorption process of ClO^-₄ on chitosan is exothermic reaction. The adsorption capacity varies from 37.98 mg·g^-1 to 34.39 mg·g^-1 with the pH changes from 3.0 to 6.0 when the initial ClO^-₄ concentration is 100 mg·g^-1. The adsorption capacity increases with the initial ClO^-₄ concentration increase, and the maximum reaches up to 128.78 mg·g^-1 at the initial ClO^-₄ concentration of 400 mg·L^-1. The equilibrium data fit Langmuir and Freundlich isothermal models well. In addition, the adsorption process can be explained by the pesudo-second-order kinetic model, and the chemisorption is the limit step for adsorption velocity. Finally, the adsorbent can be easily refreshed by pH 12.8 NaOH and repeatedly used for 10 cycles without obviously destruction.