Di Natale F, Lancia A, Molino A, Musmarra D
Department of Chemical Engineering, University of Naples Federico II, P. le Tecchio, 80-80125 Naples, Italy.
J Hazard Mater. 2007 Jul 16;145(3):381-90. doi: 10.1016/j.jhazmat.2006.11.028. Epub 2006 Nov 19.
Adsorption isotherms of chromium ions in aqueous solution have been experimentally measured on a granular activated carbon (GAC) and on a char of South African coal (CSAC). Experimental results show that the adsorption capacity for the GAC strongly depends on solution pH and salinity, with maximum values around 7mg/g at neutral pH and low salinity levels. On the contrary, the CSAC shows a smaller adsorption capacity, near 0.3mg/g, which slightly decreases by increasing pH and salinity levels. Chromium adsorption mainly depends on the availability of chromium ions in solution and on the occurrence of redox reactions between the surface groups and the Cr(VI) which lead to the formation of Cr(III). The reduction of Cr(VI) and the following sorption of Cr(III) cations appears as the leading mechanism for chromium uptake on the CSAC. A similar behaviour can be observed for the GAC at pH below 3. On the contrary, at pH>7, the multicomponent competitive adsorption of Cr(VI), OH(-) and Cl(-) has to be considered.
已在颗粒活性炭（GAC）和南非煤焦（CSAC）上对水溶液中铬离子的吸附等温线进行了实验测量。实验结果表明，GAC的吸附容量强烈依赖于溶液的pH值和盐度，在中性pH值和低盐度水平下最大值约为7mg/g。相反，CSAC的吸附容量较小，接近0.3mg/g，随着pH值和盐度水平的增加略有下降。铬的吸附主要取决于溶液中铬离子的可用性以及表面基团与Cr(VI)之间发生的氧化还原反应，这会导致Cr(III)的形成。Cr(VI)的还原以及随后Cr(III)阳离子的吸附似乎是CSAC上铬吸收的主要机制。在pH值低于3时，GAC也可观察到类似行为。相反，在pH>7时，必须考虑Cr(VI)、OH(-)和Cl(-)的多组分竞争吸附。
