Equilibrium, kinetic and thermodynamic studies on perchlorate adsorption by cross-linked quaternary chitosan
Equilibrium, kinetic and thermodynamic studies on perchlorate adsorption by cross-linked quaternary chitosan
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DOI：
10.1016/j.cej.2012.04.014
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发表时间：
2012-06
影响因子：
15.1
通讯作者：
Yanhua Xie;Shi-yu Li;Guangli Liu;Jun Wang;Ke Wu
中科院分区：
文献类型：
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作者：
Yanhua Xie;Shi-yu Li;Guangli Liu;Jun Wang;Ke Wu
采用交联季壳聚糖盐（QCS）去除高氯酸盐。考察了pH和共存阴离子对吸附过程、吸附等温线、动力学和热力学的影响。经戊二醛交联后，QCS的热稳定性和在水中的溶解度得到了改善。交联壳聚糖的最大单层吸附量为119.0mg/g，是质子化交联壳聚糖的2.5倍。在4.0 ~ 10.3的pH范围内，吸附过程几乎不受pH的影响，比在4.0 ~ 6.0的pH范围内使用质子化交联壳聚糖的吸附过程宽得多。共存阴离子对高氯酸盐吸附的影响顺序为：Cl−>NO3->SO42-。吸附数据与Langmuir和Tempkin等温线模型拟合较好。吸附动力学分析表明，化学吸附是吸附过程中的一个限速阶段。吸附热力学计算结果表明，吸附反应为放热自发反应。当NaCl浓度大于0.3%时，废吸附剂可有效再生。傅里叶变换红外光谱和溶液中Cl−浓度的变化表明，交联QCS的季铵盐基团上的氯离子可能与溶液中的高氯酸盐离子发生离子交换作用，导致高氯酸盐吸附在交联QCS上。
Cross-linked quaternary chitosan salt (QCS) was used for perchlorate removal from aqueous solution. The effect of pH and co-existing anions on the adsorption process, adsorption isotherms, kinetics and thermodynamics was investigated. The thermo stability and the solubility in water were improved after QCS was cross-linked by glutaraldehyde. The cross-linked QCS showed maximum monolayer adsorption capacity of 119.0mg/g, which was 2.5 times higher than protonated cross-linked chitosan. The adsorption process was almost independent of pH in a range from 4.0 to 10.3, which was much wider than using protonated cross-linked chitosan with applicable pH range of 4.0–6.0. The effect from co-existing anions on perchlorate adsorption followed the order: Cl−>NO3->SO42-. The adsorption data fitted Langmuir and Tempkin isotherm models well. Adsorption kinetic analysis showed that chemical adsorption was a rate-limiting stage during the adsorption process. The adsorption reaction was exothermic and spontaneous according to the calculated result of adsorption thermodynamics. The spent adsorbents could be effectively regenerated by NaCl solution with the concentration higher than 0.3%. Fourier transformation infrared spectra and the change of Cl−concentration in solution demonstrated that the ion-exchange interaction might occur between the chloride ions on the quaternary ammonium salt groups of the cross-linked QCS and the perchlorate ions in solution, resulting in the perchlorate adsorption onto the cross-linked QCS.