酸改性活性炭对甲苯、甲醇的吸附性能

分别用1 mol·L^-1硝酸、1 mol·L^-1盐酸、1 mol·L^-1硫酸对商业活性炭进行浸渍改性。采用比表面积及孔径分析仪、Boehm滴定、傅里叶转换红外光谱(FTIR)对活性炭的物化性质进行表征。以甲苯、甲醇为吸附质,在283 K下进行了固定床吸附实验。研究表明:酸改性能去除表面碱性基团,显著增加表面酸性含氧官能团的含量;酸改性活性炭的吸附量与其比表面积、总孔容、微孔孔容、表面总酸性官能团呈现出良好的线性关系;Langmuir方程比Freundlich方程更加适合描述甲苯、甲醇在活性炭上的吸附;甲醇在活性炭上为物理吸附,甲苯在活性炭上以物理吸附为主,与表面官能团之间的化学键作用能增强甲苯吸附量;甲苯、甲醇在活性炭上的微孔有效扩散系数的大小顺序为:AC-N>AC-1>AC-S>AC-C;并且甲醇的微孔有效扩散系数大于甲苯。

Adsorption of toluene and methanol onto activated carbons with acid modification

Commercial activated carbons were impregnated with 1 mol·^-1 nitric acid,1 mol·^-1 hydrochloric acid,and 1 mol·^-1 sulphuric acid separately,denoted as AC-N,AC-1,and AC-S,respectively.Specific surface area and pore distribution analyzer,Boehm titration and Fourier transformed infrared spectroscopy (FTIR) were used to measure the physicochemical properties of the activated carbons.Fixed-bed adsorption experiments were conducted at 283 K using toluene and methanol as adsorbates.The study shows that the acid modification can remove surface basic groups and increase the amount of surface acidic oxygen-containing groups.The relationship of the adsorption capacity of acid modification activated carbons and the specific surface area,total pore volume,micropore volume,amount of total surface acidic groups is linear.The Langmuir equation describes the adsorption of toluene and methanol onto activated carbons better than the Freundlich equation.The adsorption of methanol on activated carbons is physical adsorption.The adsorption of toluene on activated carbons is dominated by physical adsorption,but the chemical bond with surface functional groups can increase the adsorption capacity of toluene.The order of micropore diffusion coefficients of toluene and methanol on activated carbons is:AC-N>AC-1>AC-S>AC-C.The micropore diffusion coefficients of methanol are larger than that of toluene.