Influence of both the composition of impregnation solution and impregnation method on copper(II), chromium(VI) and silver(I) deposition on activated carbon

Abstract

The composition of a solution for impregnating activated carbon (AC) for use in a gas filter was investigated. The solution components were tetraaminocop-per(II) complex, chromium(VI), silver(l) and carbonate ions. Two methods of impregnation were investigated: ion adsorption from aqueous solution in excess and the incipient wetness method. Copper, chromium and silver con-tents on AC Were determined by atomic absorption spectrometry. The largest copper contents (4.38 and 5.00 % (w/w for two AC samples) were achieved at: c([Cu(NH3)4]2+) = 1.0 mol/L; M(Cu) i M(Cr) = 3.75: 1; M(Cu) i M(Ag) = 62: 1 and M(Cu): M(CO3) = 2: 1, using two fold impregnation by the incipient wetness method with 2.4 mL of solution per 3 g AC. The contents of chromium and silver on the same AC samples Were 1.06 and 0.0098 % for the first and 1.14 and 0.009 % for the second AC. A larger Cr content (1.57 %) was achieved from an impregnation solution in excess (c([Cu(NH3)4]2+) = 1.25 mol/L; M(Cu) i M(Cr) = 3: 1; without Ag). The largest Ag content (0.17 %) was obtained using two fold impregnation by the incipient wetness method (c([Cu(NH3)4]2+) = 0.8 mol/L; M(Cu): M(Cr) = 3.75: 1<; M(Cu) i M(Ag) ( 80: 1 and M(Cu) i M(CO3) = 1 i 1.32). Larger metal contents were obtained using two fold impregnation by the incipient wetness method. Further work is needed on the determination of the influence of carbonate ions both on the solution stability and metal deposition on AC.