SO_2在活性炭上的吸附平衡、动力学及热力学研究

Equilibrium,kinetics and thermodynamics of SO_2 adsorption on activated carbon

为深入研究SO2在活性炭上的吸附过程,基于固定床反应器研究了某商业活性炭对烟气中SO2的吸附性能,考察了SO2体积分数、吸附温度对活性炭吸附SO2的影响,分析了SO2在活性炭表面的吸附平衡、吸附动力学和热力学特性。结果表明,随着SO2体积分数的增加,SO2初始吸附速率和平衡吸附量增加;随着吸附温度的增加,SO2初始吸附速率和平衡吸附量降低。活性炭对SO2的吸附平衡数据符合Langmuir和Freundlich吸附等温线模型;SO2在活性炭上的动态吸附过程符合Bangham吸附动力学模型。吸附热力学研究表明,吸附过程中焓变为-19.21 kJ/mol,吸附自由能变为-10.17^-9.29 kJ/mol,吸附熵变为-27.69^-27.17 J/(mol·K),该吸附过程是一个自发、放热、熵降低过程,升温不利于SO2在活性炭上的吸附。

In order to study the process of SO2 adsorption on activated carbon,the flue gas SO2 adsorption removal by activated carbon was investigated based on a fixed bed reactor. The effects of SO2 inlet concentration and adsorption temperature on SO2 adsorption were also investigated and the adsorption equilibrium, kinetics and thermodynamics were analyzed. The initial SO2 adsorption rate and the amount of SO2 adsorbed increase with the SO2 inlet concentration increase,and decrease with the adsorption temperature increase. Langmuir and Freundlich adsorption isotherm model presents a better fitted results for SO2 adsorption on activated carbon. The Bangham kinetic model can be used to pre- dict the kinetics of SO2 adsorption on activated carbon. The thermodynamics results indicate that the adsorption enthal- py is -19.21 kJ/mol, the Gibbs free energy is -10. 17--9.29 kJ/mol, and the entropy is -27.69--27. 17 J/ （mol · K） ,therefore,the adsorption is a spontaneous, exothermic, and entropy decreasing process. The SO2 adsorption on activated carbon is unfavorable at higher temperature.