香草醛改性壳聚糖对镉离子的吸附热力学和动力学

Adsorption thermodynamics and kinetics of Cd(Ⅱ) ions by modification of chitosan with vanillin

研究了微波辐射条件下香草醛改性壳聚糖(V-CTS)对Cd2+离子的吸附性能,测定了吸附等温线和吸附动力学曲线。结果表明,该吸附剂对Cd2+离子的吸附行为符合Freundlich吸附等温式,在298～318K温度范围内,焓变ΔH=24.22kJ/mol,表明吸附是吸热过程。吸附动力学符合Lagergren二级吸附速率方程,反应活化能为25.58kJ/moL,表明V-CTS对金属离子的吸附由化学反应控制,而非扩散控制。吸附剂解吸再生循环使用4次后,镉离子的吸附容量仅减少18.9%,该吸附剂具有较好地再生使用性。

Chitosan modified by vanillin（V-CTS） were prepared with microwave radiation method for adsorption of Cd（ Ⅱ ）ions were investigated. V-CTS was characterized by means of FT-IR,SEM and XRD. Results showed that the isothermal adsorption follows the isothermal adsorption model of Freundlich. Enthalpy change at ad- sorption temperatures in range of 298-318K is 24. 2174kJ/mol, which suggests that adsorption process is endo-thermic. The adsorption kinetics followed the mechanism of the pseudo-second-order equation and activity energy is 25. 57597kJ/mol, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. After 4 times regeneration experiment,the uptake amount of Cd（ 11 ）ions reduced 18.9%.