Adsorption of zinc on manganite (γ-MnOOH):: particle concentration effect and adsorption reversibility

The adsorption and desorption processes of Zn(II) on gamma-MnOOH as a function of particle concentrations (C-p) were studied. An obvious C-p effect was observed in this adsorption system. The degree of adsorption hysteresis increased greatly with the increasing of Cp, indicating that the extent of the real metastable-equilibrium states deviating from the ideal equilibrium state was enhanced with the increasing of C-p. The C-p-reversibility relationship confirmed the motastable-equilibrium adsorption (MEA) inequality (Pan, 1998a), which was the core formulation of the MEA theory. Because the MEA inequality was based on the basic hypothesis of MEA theory that adsorption density Gamma is not a state variable, the C-p-reversibility relationship gave indirect evidence to the basic hypothesis of MEA theory.