载铁改性活性炭对溶液中六价铬Cr(VI)的吸附研究

摘要

With the progress of society and the development of modern industry, industrial "three wastes" emissions continued to increase, which brought great threat to the development of ecological environment.It caused people's survival environment to deteriorate continuously.The primary typical pollutant in chromium-containing waste water was hexavalent chromium [Cr (Ⅵ)].Different iron salt solution impregnating phosphoric acid activated carbon (Fe-PAC) was adopted, investigated the adsorption of Cr (Ⅵ) in the water.The factors of iron salt solution concentration, pH of solution, and adsorption equilibrium time, adsorption kinetics were studied.The physicochemical properties of modified activated carbon were analyzed using XPS and BET.The results showed that: modification of activated carbon by ferrous sulfate solution was chose to adsorb Cr (Ⅵ).The activated carbon adsorption capacity of Cr (Ⅵ) after the modified carrier from 10.18 mg/g up to 22.56 mg/g.Removal efficiency of Cr (Ⅵ) reached 95% while the pH of solution was at 2.0.The XPS result showed that there were divalent iron oxide and ferric oxide in the surface of activated carbon.Adsorption process was in line with the pseudo second order equation and dominated by chemical adsorption.By using nitrogen adsorption isotherm, the results showed that the specific surface area of the activated carbon decreased, because the pores of activated carbon were been blocked by iron oxide.%以磷酸法活性炭(PAC)为原料,通过不同铁盐溶液浸渍法制备载铁改性活性炭(Fe-PAC),采用二苯碳酰二肼分光光度法检测其对水中Cr(Ⅵ)的吸附效果,考察了铁盐浓度、溶液pH等因素对吸附效果的影响,研究了吸附平衡时间、吸附动力学,利用XPS、BET等方法对改性活性炭进行表征.结果表明:硫酸亚铁溶液浸渍改性活性炭对Cr(Ⅵ)吸附最佳,硫酸亚铁溶液浓度为0.20 mol/L,载铁改性后活性炭对水中Cr(Ⅵ)的吸附量从10.18 mg/g提高到22.56 mg/g;溶液pH为2.0时,Cr(Ⅵ)去除率达到95%.通过XPS检测改性后活性炭表面负载有二价铁及三价铁氧化物;吸附动力学实验表明改性活性炭对Cr(Ⅵ)的吸附符合伪二级动力学方程,以化学吸附占主导.采用氮气吸附等温线对其比表面积及孔隙分布分析,结果表明由于铁氧化物堵塞孔隙,改性后活性炭的比表面积减小.