纳米腐植酸对镉离子的吸附热力学及动力学

Thermodynamics and Kinetics of Cadmium Ions Adsorption by Nanoscale Humic Acid

研究了采用碱溶酸析法配加高剪切技术制备的纳米腐植酸对重金属镉离子的吸附性能,用原子力显微镜（AFM）、红外光谱（FT-IR）、扫描电子显微镜（SEM）、比表面积测试仪（BET）等对纳米腐植酸进行表征,绘制了静态平衡吸附等温线及吸附动力学曲线。实验结果表明：吸附剂纳米腐植酸对镉离子的吸附较符合Freundlich模型,在288-308 K温度下,吸附焓变？H=24.22 k J？mol？1,表明吸附是吸热过程,吸附动力学符合HO二级吸附速率方程,反应的表观活化能Ea=25.58 k J？mol？1,表明纳米腐植酸对重金属离子的吸附是化学反应控制,而非扩散所控。吸附剂纳米腐植酸解吸再生循环使用5次后,Cd2＋的吸附容量仅减少18.9%,说明该吸附剂具有较好的解吸再生性能。

Nanoscale humic acid was prepared by alkali-solution/acid-isolation together with high sheafing methods, which was used in the adsorption of cadmium ions. The prepared acid was characterized by means of AFM, FT-IR, SEM and BET, and the static equilibrium adsorption isotherm and adsorption kinetic curves were obtained. The results show that the adsorption process follows the Freundlich isothermal adsorption model. The enthalpy change at temperatures of 288-308 K is 24.22 kJ.mol^-1, which suggests that adsorption process is endo-thermic. The adsorption kinetics follows the psendo-second-order equation and the apparent activition energy is 25.58 kJ.mol^-1. This result indicates that the adsorption process is chemical reaction controlled rather than diffusion controlled. The adsorption capacity decreases 18.9% after 5 times of acid reusing and this result demonstrates that the adsorbent has good regenerability.