DMF在大孔吸附树脂上的吸附热力学及动力学研究

Study on the adsoption kinetics and thermodynamics of DMF on macroporous adsorbents

研究了大孔吸附树脂吸附N,N-二甲基甲酰胺(DMF)的热力学与动力学特性.经过初步筛选,发现NKA-Ⅱ型大孔吸附树脂对DMF具有良好的吸附与再生性能.在温度为298、和318K条件下分别测定了吸附平衡数据并应用Freundlich和Langmiur等温吸附方程进行拟合,结308果表明,DMF在NKA-Ⅱ型大孔吸附树脂上的吸附平衡符合Freundlich等温吸附方程.在此基础上,通过热力学分析发现ΔH>0、ΔG<0、ΔS>0,表明DMF在大孔吸附树脂上的吸附属于可自发进行的物理吸附,吸附过程吸热,但吸附热较小,温度对吸附过程的影响较小.吸附动力学研究中分别采用一级速率方程、准二级速率方程和二级速率方程对吸附过程进行模拟,结果表明,准二级动力学方程的计算值与实验值吻合良好,适合描述NKA-Ⅱ型大孔吸附树脂对DMF的吸附过程.

The adsorption thermodynamics and kinetics of DMF on macroporous resin NKA- lI were investigated. The macroporous resin NKA-II has better adsorption and regeneration performance for DMF. Series of adsorption equilibrium experiments were conducted in temperature of 298 K, 308 K and 318 K. The adsorption equilibrium data were fitted to Langmuir and Freundlich isotherm equations. The results showed that the adsorption equilibrium data were agreed with Freundlich isotherm well. Thermodynamic analysis suggested AH 〉 0, AG 〈 0 and AS 〉 0. The adsorption of DMF on NKA- 11 was a spontaneous physical adsorption process, artd AH of adsorption was so small that the temperature had little influence on adsorption process. The kinetics data were fitted to first order model, pseudo-second order model and second order model respectively. The adsorption process of DMF on macroporous resin NKA-II could be described well by pseudo-second order model.