氧化改性和热处理联合作用后活性炭吸附六价铬的研究

Hexavalent Chromium Adsorption of Activated Carbon after Co-modification of Nitric Acid Oxidation and Thermo Process

采用不同浓度硝酸氧化联合热处理的方法对活性炭(AC)进行表面化学改性,并研究了改性之后活性炭的Cr(VI)的吸附性能以及溶液初始浓度、pH、温度和时间等因素对其吸附性能的影响。研究发现,在空气氛围下,经20wt%的沸腾的硝酸溶液氧化3 h,450℃条件下马弗炉热处理2h后活性炭(MAC-20)的Cr(VI)的吸附性能最好,饱和吸附容量为34.89mg·g^(-1),比AC增加了10.77mg·g^(-1)。溶液pH是MAC-20的Cr(VI)吸附性能的主要影响因素,pH=2,MAC-20达到最大吸附值。MAC-20的Cr(VI)吸附规律符合Lagergren准二级反应速率模型,Cr(VI)在MAC-20表面的吸附行为主要以化学吸附为主。

This paper carried out a way of the surface chemical modification of activated carbon(AC)by combining nitric acid oxidation treatment and heat treatment in the muffle furnace.Furthermore,the adsorption capacity of C(VI)and the initial concentration of solution,pH,temperature and time on the adsorption properties of activated carbon after modification were also studied.The results showed that the MAC-20 which was made by the method of oxidizing by the boiled nitric acid for 3 h and placing in a tube furnace containing air at 450℃for 2 h had the best adsorption property of hexavalent chromium and its Saturated adsorption capacity of 34.89 mg·g-1 increasing by 10.77 mg·g-1 compared with that of AC.During the adsorption process,the initial pH of solution was the main factor and the optimum pH was 2.The pseudo-second-order equation provided the best correlation of the equilibrium data,indicating that the removal of hexavalent chromium onto MAC-20 was mainly by chemical adsorption.