SO_2在活性炭表面的吸附平衡和吸附动力学

Adsorption equilibrium and kinetics of SO_2 on activated carbon

基于固定床反应器研究烟气中SO2在活性炭表面的吸附平衡和吸附动力学。结果表明:活性炭吸附SO2在初始阶段呈现较快的吸附速率,该阶段和表面吸附有关;随着吸附的进行,表面活性位逐渐被占据,吸附速率下降,粒内扩散起主要作用;在接近吸附饱和阶段,SO2吸附量增加缓慢,SO2吸附与H2SO4的脱附有关。与2 mm活性炭相比,0.075 mm活性炭呈现较快的SO2吸附速率和较高的吸附量;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。SO2在活性炭上的动态吸附符合Bangham吸附动力学模型。用Langmuir和Freundlich吸附等温线模型拟合吸附数据,发现Freundlich模型能够很好地预测SO2在活性炭表面的吸附平衡。

The adsorption equilibrium and kinetics of the flue gas SO2 removal on activated carbon were investigated based on a fixed bed reactor.The results show that there is a rapid SO2 adsorption rate on activated carbon in the initial stage,which is determined by the surface adsorption,after that the adsorption rate drops sharply due to the effect of intraparticle diffusion,and then the adsorption rate drops slowly and the amount of SO2 adsorbed increases slowly until the adsorption equilibrium,which is determined by the desorption rate of H2SO4.The SO2 adsorption rate and the amount of SO2 adsorbed increases with decreasing the particle size of activated carbon and increasing SO2 inlet concentration.The Bangham kinetic model can be used to predict the kinetics of SO2 adsorption on activated carbon of different particle size under different SO2 inlet concentration.Compared with Langmuir adsorption isotherm model,Freundlich adsorption isotherm model presents better fitted results for SO2 adsorption equilibrium on activated carbon of different particle size.