Equilibrium and dynamic study on hexavalent chromium adsorption onto activated carbon

Dynamic tests at pH 11 were well described considering the external mass transfer as the rate controlling step. Differently, for dynamic tests at pH 6 the same model provided a satisfying description of the experimental breakthrough curves only until a sorbent coverage around 1.6 mg g−1. Above this level, a marked reduction of the breakthrough curve slope was observed in response to a transition to an inter-particle adsorption mechanism.