酸、碱改性活性炭对甲醇、甲苯吸附性能

Adsorption of Methanol and Toluene onto Activated Carbon with Acid-Base Modified

分别采用硝酸和氢氧化钠对活性炭进行改性,利用比表面积及孔径分析仪(BET)、扫描电镜(SEM)、Boehm滴定法对活性炭物化性质进行表征,测试改性活性炭对甲醇、甲苯吸附性能。结果表明,经过酸、碱改性后的活性炭比表面积、总孔容、微孔孔容均有所增大。酸改性表面酸性基团增加,碱改性后活性炭酸性基团减少。酸改性后的活性炭对甲醇、甲苯吸附能力有所下降,后经碱改性的活性炭吸附能力均有不同程度的提高。单组分吸附实验时,甲醇穿透曲线斜率要大于甲苯,穿透时间早于甲苯。在多组分吸附过程中会出现甲苯取代甲醇的吸附现象,使得已经被吸附的甲醇发生脱附,此时甲醇的出口浓度大于进口浓度,形成峰值效应。

The activated carbon was modified with nitric acid and sodium hydroxide respectively, and the physicochemical properties of the activated carbon were characterized by specific surface area and pore size analyzer （BET）, scanning electron microscope （SEM） and Boehm titration. The adsorption performance of modified activated carbon for methanol and toluene was tested. The results show that the specific surface area, total pore volume and micro-pore volume of activated carbon modified by acid and alkali are increased. The number of acidic groups on the surface is increased after acid-modification, and after the alkali modification, the activated carbon acid groups are reduced. The adsorption capacity of methanol and toluene is decreased for acid-modified activated carbon, and for the alkali-modified activated carbon, the adsorption capacity is improved to varying degrees. For single-component adsorption experiments, the slope of methanol breakthrough curve is greater than that of toluene and the breakthrough time is earlier than that of toluene. In the process of multi-component adsorption, replacement adsorption of toluene to methanol occurs, so that the adsorbed methanol is desorbed.