根据热重分析结果,确定了活性炭热改性的温度条件;采用Boehm滴定、傅里叶转换红外光谱仪(FTIR)、比表面积分析仪对活性炭表面物化性质进行了测试;以甲苯、丙酮、二氯乙烷、甲醇为吸附质,在283K下进行了固定床吸附实验,探讨了改性前后活性炭表面结构变化与吸附量之间的关系,同时计算了相应的动力学参数和吸附能。实验结果表明,热改性可以改善活性炭的孔径分布和改变表面官能团的分布,吸附量与有效孔容呈明显的线性关系;一阶动力学方程和二阶动力学方程均可描述4种吸附质在活性炭上的吸附过程;孔内扩散模型表明改性活性炭对有机气体的吸附速率均大于未改性活性炭;4种吸附质在活性炭上的吸附能均小于20kJ.mol-1,表明活性炭对4种有机气体以物理吸附为主。
According to the TGA results,the temperature requirement for modifying process of activated carbons was discussed.The physicochemical properties of modified activated carbon surfaces were examined using Boehm titration,Fourier transformed infrared spectroscopy(FTIR)and BET specific surface area analyzer.Fixed-bed adsorption experiments were conducted at 283 K,in which toluene,acetone,dichloroethane and methanol were used as adsorbate,separately.With the correlation analysis on experimental results and surface characterization results,the dynamic parameters and adsorption energy were calculated.The results show that the pore size distribution and surface functional groups of activated carbons are changed after the thermal treatment,and the correlation between adsorption capacity and effective pore volume is linear.Both pseudo-first-order and pseudo-second-order kinetic equations are appropriate to characterize the adsorption process of these four adsorbates on activated carbon.In addition,intra-particle diffusion model shows that the rate of adsorption of the organic gases on activated carbon is greater than that on unmodified one.The adsorption energy of all the four adsorbates is smaller than 20 kJ·mol-1,indicating that the adsorption is dominated by physical adsorption.