活性炭电极电容法脱盐性能的研究

研究了活性炭用于电容法脱盐时的电化学性能。用恒压充放电方法研究了操作电压对活性炭电吸附性能的影响,比较了活性炭对不同金属离子的电吸附性能,初步研究了活性炭物性参数与其电吸附性能的关系。结果表明,操作电压与活性炭电吸附容量呈线性关系(0.6~1.2 V),活性炭电极经恒压充放电循环后动态电吸附容量有一定的衰减,这可能与活性炭的表面官能团有关;4种活性炭对质量分数0.1%的碱金属和碱土金属氯化物吸附性能的比较发现,702#活性炭综合性能最好,对于KC l的吸附容量达27.9 mg/g,对NaC l的吸附容量达19.0 mg/g,对于MgC l2的吸附容量达17.0 mg/g;离子特性影响活性炭的电吸附性能;活性炭的比表面积和孔结构是影响活性炭电吸附性能的两个关键因素,比表面积较大、中孔较丰富的活性炭其电吸附性能更好。

Study of Activated Carbon for Capacitive Desalination

Capacitive desalination properties of activated carbon were investigated by using potentiostatic charge/discharge technique.The influence of operating voltage on ion adsorption amount of activated carbon was studied first,and then electrostatic adsorption amounts of activated carbon to alkali and alkaline earth metal chlorides were compared.The correlation between ion electrostatic adsorption amount and structural properties of activated carbon was also discussed.It was found that the ion electrostatic adsorption amount increases as the operating voltage increases in the voltage range of 0.6~1.2 V.Capacitive desalination performance was deteriorated to a certain degree after potentiostatic charge/discharge cycling;this might be attributed to the badly cycling performance of the surface functional group of activated carbon.Comparison test of electrostatic adsorption amount of alkali and alkaline earth metal chlorides for the four activated carbons was carried out in 0.1% aqueous solution.It was found that the 702# activated carbon has the best performance,obtaining adsorption amount of 27.9 mg/g to KCl,19.0 mg/g to NaCl and 17.0 mg/g to MgCl2.The characteristics of ions have an effect on the desalination properties of activated carbon.The capacitive desalination properties of activated carbons depend mainly on the specific surface area and pore structure;activated carbons with larger BET surface area and mesopore volume have better performance.