DMF在大孔吸附树脂上的吸附热力学及动力学研究

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.

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

The adsorption thermodynamics and kinetics of DMF on macroporous resin NKA-Ⅱ 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 ΔH>0,ΔG<0 and ΔS>0.The adsorption of DMF on NKA-Ⅱ was a spontaneous physical adsorption process,and ΔH 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.