Separation of tungsten from Mo-rich leach liquor by adsorption onto a typical Fe-Mn cake: Kinetics, equilibrium, mechanism and thermodynamics studies

CATEGORY: SEPARATION
Separation of tungsten from Mo-rich leach liquor by adsorption onto a typical Fe-Mn cake: Kinetics, equilibrium, mechanism and thermodynamics studies
Abstract
RAJIV RANJAN SRIVASTAVA , Min-seuk Kim , and Jae-chun Lee
Abstract
Researchers employed a typical mixed hydrated oxide cake of iron and manganese (FMC) to adsorb and separate tungsten from Mo-rich leach liquor obtained from the ammonia leaching of oxidatively roasted, spent hydro-desulfurization catalysts. The FMC is itself a byproduct of the ammonia leaching of reduced manganese nodules.
They studied the adsorption kinetics and correlated it with the common isotherm equations of Langmuir and Freundlich. The data fit well with the Freundlich model and showed first-order kinetic behavior. The plot of qt vs. t0.5 indicates boundary layer diffusion as the rate-limiting step of the adsorption process. The calculated thermodynamic parameters, ΔG, ΔH and ΔS, suggest that the adsorption of tungsten onto FMC is a spontaneous, exothermic and physical sorption process.
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