改性活性炭对甲基橙的吸附

Adsorption of Methyl Orange on Modified Activated Carbon

用盐酸和氨水对活性炭进行改性获得改性活性炭,将其用于处理甲基橙废水,考察了改性条件、振荡速度和温度等因素对甲基橙吸附性能的影响,采用吸附等温模型和吸附动力学模型进行拟合,并分析吸附过程的热力学特征.结果表明,盐酸改性活性炭对甲基橙的吸附效果优于氨水改性活性炭,在甲基橙初始浓度60 mg/L、溶液体积50 m L、温度20℃、振荡速度100 r/min、盐酸改性活性炭投加量0.2 g时,24 h基本达到吸附平衡,甲基橙去除率为93.7%.不同温度下,盐酸改性活性炭对甲基橙的吸附符合Langmuir(RC^2>0.95)和Freundlich(RC^2>0.97)吸附等温模型,饱和吸附量达112.7 mg/g.热力学参数DG0<0,DH0>0,DS0>0,表明盐酸改性活性炭对甲基橙的吸附是自发吸热反应,其吸附动力学可用准二级动力学方程描述,随振荡速度增加,吸附速率常数增加.

Activated carbon was modified by hydrochloric acid and aqueous ammonia and used as adsorbent to remove methyl orange（MO） from wastewater. The effects of modification condition, shaking speed and temperature on its adsorption performance of MO were examined. The adsorption data were simulated by both adsorption isotherm and kinetic models, and the adsorption thermodynamics was also analyzed. The results showed that the adsorption capacity of hydrochloric acid modified activated carbon for MO was better than that of ammonia modified one. The adsorption equilibrium was achieved with the removal rate of MO 93.7% within 24 h under the conditions of initial MO concentration of 60 mg/L, solution volume of 50 m L, temperature of 20 ℃ and shaking speed of 100 r/min. The adsorption data of hydrochloric acid modified activated carbon for MO fitted well to Langmuir（RC^2〉0.95） and Freundlich（RC^2〉0.97） adsorption isotherm models, and its saturated adsorption capacity reached up to 112.7 mg/g. Thermodynamic parameters, such as DG^0〈0, and DH^0〉0,DS^0〉0, showed that the adsorption of MO on hydrochloric acid modified activated carbon was a spontaneous and endothermal reaction. The adsorption kinetics could be well described by pseudo-second-order kinetic model. The adsorption rate constant increased with the increase of shaking speed.