Adsorption of trivalent cations on silica - II. Temperature effect

The temperature effect on the magnitude of adsorption was used to explain t he mechanism of adsorption of gadolinium on silica at very low concentratio ns. Standard enthalpy of adsorption of gadolinium equals 36 kJ mol(-1) for a total Gd concentration of 2 x 10(-8) mol dm(-3) and 67 kJ mol(-1) for 2 x 10(-5) mol dm(-3). This result confirms the hypothesis that the Gd adsorpt ion at low initial concentration is governed by formation of strong ternary surface complexes involving anionic impurities. (C) 1999 Academic Press.