The Isosteric Heat of Adsorption of Sr2+, Ce3+, Sm3+, Gd3+, Th4+ and UO22+ Ions on Activated Charcoal

Abstract

The values of the isosteric heat of adsorption (qst) of Sr2+, Ce3+, Sm3+, Gd3+, Th4+ and UO22+ ions on activated charcoal have been calculated at different surface coverages and temperatures by applying the Clausius–Clapeyron equation. The variation of qst with surface coverage indicates the heterogeneous nature with varying activities of the activated charcoal surface. The behaviour of qst values with temperature suggests that two types of adsorption processes occur simultaneously; one with a small activation energy and the other with a large activation energy. A large increase in the qst values indicates that increasing temperature changes the physical adsorption process to chemisorption.