硫脲改性壳聚糖对水中Cr(Ⅵ)与Ni(2+)的吸附性能研究-《电镀与精饰》

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Title:: Adsorption of Cr( Ⅵ) and Ni~(2+) by Chitosan Modified Using Thiourea

摘要:: 以壳聚糖和硫脲为原料,经环氧氯丙烷交联,制得硫脲改性壳聚糖颗粒,通过吸附实验考察了pH、吸附时间对Cr(Ⅵ)、Ni2+吸附的影响。结果表明,硫脲壳聚糖颗粒对Ni2+吸附的最佳pH为6,对Cr(Ⅵ)吸附的最佳pH为1,最佳吸附t为2h。利用准一级反应动力学模型和准二级反应动力学模型对实验数据进行拟合,并分别采用Freundlich模型、Langmuir模型对吸附等温线进行拟合。结果表明,吸附符合准二级动力学模型,以化学吸附为主。吸附等温线用Langmuir模型拟合结果最好。在初始质量浓度80mg/L,θ为25℃时,Ni2+,Cr(Ⅵ)的饱和吸附量可达40.98mg/g和33.33mg/g。

Abstract:: Chitosan particles cross linked epichlorohydrin were prepared by a mixture of thiourea and chitosan. The pH value and effects of reaction time on the adsorption capacity of the particles for Cr( Ⅵ)and Ni2 +were investigated. It was found that the adsorption capacity of Ni2 +increased with the increase of pH value,and the optimum value is 6,but Cr( Ⅵ) decreased with the increase of pH value,and the optimum value is 1,the optimal adsorptive time is 120 min. The kinetics was evaluated utilizing the pseudofirst-order reaction and pseudo-second-order reaction models,and the equilibrium data were analyzed using the Freundlich and Langmuir adsorption isotherm models. The results showed that the adsorption kinetics followed the mechanism of the pseudo-second-order reaction equation,which demonstrated that chemical adsorption held a dominant position. The equilibrium data were fitted with Langmuir isotherm well. Under the conditions of initial concentration 80 mg / L,and temperature 25 ℃,the maximum adsorption capacities of Ni2 +and Cr( Ⅵ) reached 40. 98 mg / g and 33. 33 mg / g,respectively.