The dynamics and equilibrium of ammonium removal from aqueous solution by Na-Y zeolite

Abstract

AbstractThe ammonium removal from aqueous solution using Na-Y zeolite was investigated. The Na-Y zeolite was selected from a group of Beta, A, X, and Y zeolites, which were first screened to identify the best candidate for the ammonium removal. Among the considered zeolites, Na-Y and Na-X zeolites had the highest adsorption efficiencies, presumably due to a combination of their qualifying characteristics such as low Si/Al ratio, high surface area, and large pore size. The order at which the different investigated Y zeolites showed affinity for ammonium uptake was Na-Y >> Cs-Y ≈ K-Y > Mg-Y = Ca-Y > H-Y. For the Na-Y zeolite, it was found that the ammonium removal dynamics followed a pseudo-second-order kinetic model while the Langmuir adsorption isotherm fitted the equilibrium data well. Furthermore, it was deduced that the ammonium removal proceeded through two mechanisms: ion exchange and molecular adsorption. Three regeneration methods for restoring the adsorption efficiency of the spent zeolites were e...