Aqueous nitrate removal by D417 resin: thermodynamic, kinetic and response surface methodology studies

In this study, D417 resin was characterized using scanning electron microscopy, Fourier transform infrared spectrometry and thermogravimetric analysis (TGA). Batchwise experiments were carried out to evaluate the thermodynamic and kinetic behaviors of the aqueous nitrate adsorption onto D417 resin. Response surface methodology (RSM) with Box–Behnken design (BBD) was employed to analyze the competition disturbance and matrix effects in terms of pH, organic matter concentration, contact time (CT) and salinity. Test results revealed that the resin was composed of the quaternary ammonium functional group and exhibited a considerable adsorption capacity of 23.46 to 22.81 mg·g−1 at the temperature ranging from 293.15 to 313.15 K. Mean free energy of adsorption calculated from the Dubinin–Radushkevich model showed that the adsorption was realized through ion-exchange pathway. Gibbs free energy change, enthalpy change and entropy change illustrated that the aqueous nitrate sorption was feasible and spontaneous. It was also found that the pseudo-second-order model could well describe the adsorption kinetics, and the intraparticle diffusion was the main rate-limiting step. RSM with BBD showed that CT and salinity had significant effects on aqueous nitrate adsorption, whereas the impacts of pH and dissolved organic matter were negligible. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.