Equilibrium isotherm and kinetic modeling of the adsorption of nitrates by anion exchange Indion NSSR resin

This paper describes the adsorption capacity of ion exchange Indion NSSR resin for removal of nitrates from aqueous solution. Adsorption capacity of resin was investigated under different conditions viz variations in adsorbent dose, initial concentrations of nitrate and pH. The fitting of the Freundlich, Langmuir and Dubinin–Radushkevich adsorption models to the equilibrium data was investigated. The equilibrium data obtained in this study were found to follow the Langmuir adsorption isotherm. The maximum sorption capacity was 119 mg/g as per Langmuir isotherm at 35 °C under this particular study. The rate parameters for the intra particle diffusion have been estimated for different initial concentrations. In batch adsorption processes, the adsorbate molecules diffuse in porous adsorbent and rate process usually depends on t0.5 rather than the contact time. The nitrate adsorption on Indion NSSR resin from aqueous solution follows first order reversible model. The nitrate adsorption capacity of ca 77 mg/g was observed for the Indion NSSR resin from the column study with specific conditions of operation.

Research highlights
► High adsorption capacity of Indion NSSR resin for removal of nitrate.
► Estimation of various adsorption isotherms for designing nitrate removal treatment.
► Resin provides potential for nitrate removal and subsequent catalytic reduction.