赋硫活性炭对Cr(VI)的吸附机理

Adsorption mechanism of Cr( VI) by sulfur-impregnated activated carbon

以商品活性炭(AC)为原料,制备具有含硫官能团的赋硫活性炭(SAC),对比研究了2种活性炭对Cr(VI)的等温吸附及吸附动力学;同时,用付立叶变换红外光谱(FT-IR),拉曼光谱(Raman),X射线光电子能谱(XPS)等分析方法表征吸附前后的活性炭表面官能团的变化。结果表明,赋硫改性使活性炭表面生成了S—S,噻吩,O=S=O等含硫官能团,为吸附Cr(VI)提供更多活性位点。Langmuir吸附模型非线性拟合能较好地描述AC对Cr(VI)的等温吸附,而SAC对Cr(VI)的吸附过程则以Freundlich吸附模型非线性拟合结果更好,准二级动力学模型非线性拟合比较吻合AC与SAC对Cr(VI)的吸附动力学。与AC相比,SAC对Cr(VI)的平衡吸附量在25、35和45℃下分别增加了55.20%、29.16%和85.76%。

Sulfur-impregnated activated carbon（ SAC） was derived from commercial activated carbon（ AC）. SAC and AC were used as adsorbents to investigate the adsorption isotherms and adsorption kinetics of Cr（ VI） in aqueous solutions. FT-IR,Raman,and XPS analyses were employed to characterize the sulfur-containing functional groups on AC and SAC before and after adsorption. The results showed that the surface functional groups of S—S,thiophene and O=S=O were acquired by the process of sulfur impregnation. These groups provided a large number of activated sites for the adsorption of Cr（ VI）. The non-linear fitting of the Langmuir model was applied to describe the adsorption isotherms of Cr（ VI） for AC,while the adsorption process for SAC obeyed the non-linear fitting of the Freundlich model. The non-linear form of the pseudo-second-order kinetics model could be applied to describe the adsorption kinetics of Cr（ VI） for both AC and SAC. The equilibrium adsorption capacity of SAC increased by 55. 20%,29. 16%,and 85. 76% at 25,35,and 45 ℃,respectively,compared with that of AC.