改性活性炭对镉的吸附研究

Research on Cadmium Adsorption by Modified Granular Activated Carbon

研究镉在表面氧化改性的颗粒活性炭上的吸附行为．考察离子强度、pH值、温度和镉初始浓度对吸附的影响，并进行相应的动力学与热力学计算．结果表明，实验范围内，活性炭对镉的吸附在pH=2～7范围内与pH值呈正相关，增加离子强度对吸附有一定的阻碍作用；吸附动态曲线符合二级动力学模型；活性炭与镉之间的标准吸附热约为-25．29k1．mol^-1，整个温度范围内吸附是自发的放热过程．

Cadmium adsorption behaviour of modified granular activated carbon was investigated. Experiments were conducted to study the effect of parameters, such as ionic strength, pH, equilibrium time and initial cadmium concentration. The adsorption capacity of modified granular activated carbon enlarged with an increase in pH, and reduced with an increase in ionic strength. The adsorption pro- cess followed pseudo-second order rate model. Thermodynamic calculation was employed based on adsorption isotherms at different temperatures. The average change of standard adsorption heat AH was - 25.29 kJ. mol^-1. Negative △H and △G values indicate the adsorption process for cadmium onto the studied activated carbon is exothermic and spontaneous.