水中高氯酸根的颗粒活性炭吸附过程及影响因素分析

Adsorption of Perchlorate in Water by Granular Activated Carbon and Impact Factors Analysis

通过批量实验研究了颗粒活性炭(GAC)对水中高氯酸根(ClO4-)的吸附特性,考察了pH、ClO4-初始浓度和共存阴离子对吸附作用的影响,并分析了吸附动力学和等温吸附模型.结果表明,GAC对ClO4-的吸附容量在碱性条件下减小,随初始浓度升高而增大,共存阴离子与ClO4-在GAC上存在竞争吸附,其影响顺序为SO42->NO3->CO32->H2PO4->BrO3-≈Cl-.ClO4-在GAC上的吸附最符合准二级动力学模型,吸附中存在大孔扩散过程,且孔扩散可能为GAC吸附ClO4-的主要速率控制步骤.试验浓度范围内吸附过程符合Langmuir、Freundlich和Tempkin 3种等温吸附模型,吸附过程是自发且放热的,温度升高不利于GAC对ClO4-的吸附,温度为288、298和308 K时的饱和吸附容量分别为13.00、11.21和8.04 mg.g-1.说明GAC虽较易吸附水中ClO4-,但必须控制反应条件,如温度、pH和共存阴离子浓度等,以取得最佳吸附效果.

The adsorption of perchloric ion（ClO^-4） on granular activated carbon（GAC） was studied in aqueous solution through batch experiments.The effect of pH,initial ClO^-4 concentration and co-existed anions on ClO^-4 adsorbed by GAC,adsorption kinetics and isothermal models were studied.The results show that the adsorption capacity of ClO^-4 on GAC decreases in the alkaline solution,and increases with the increasing initial concentration.The competitive adsorption exists between co-existed anions and ClO^-4 on GAC and the order of competitive effect is SO4^2-4〉NO^-3〉CO3^2-〉H2PO^-4〉BrO3^-≈ Cl^-.The adsorption process follows pseudosecond order kinetics.The existed pore diffusion probably is the main rate-controlling step of adsorption process.In addition,adsorption of ClO^-4 on GAC fits the Langmuir,Freundlich and Tempkin isothermal models in the range of experimental concentration.The adsorption of ClO^-4 on GAC is spontaneous and exothermic,and the increase of temperature decreases the adsorption capacity.The maximum adsorption capacity is 13.00,11.21 and 8.04mg·g^-1 at the temperatures of 288,298 and 308 K,respectively.Adsorption of ClO^-4 on GAC is favorable,but the reaction conditions,such as temperature,pH and co-existed concentration,should be controlled to improve the adsorption efficiency.