Retention of Nitrates Discharged from Photovoltaic Baths by Adsorption onto Mg-Al-LDH: Parametric Study

Abstract

Adsorption of nitrates ions (N O 3 - ) from aqueous solutions onto an anionic synthetic clay Mg-Al-LDH has been studied using a batch adsorber. Mg-Al-LDH was prepared by co-precipitation method at constant pH and characterized by X-Ray and FTIR. Nitrates ions adsorption parameters were optimized (contact time, pH, initial NO₃^- concentration, LDH mass...). Equilibrium isotherm studies were done to evaluate the maximum adsorption capacity of Mg-Al-LDH. The localized exchange sites on the heterogeneous adsorbent surface of Mg-Al-CO₃^2- receive the nitrates species in multilayers with possible interactions between the adsorbed molecules by a chemisorption mechanism. Experimental kinetics data of nitrate adsorption on Mg-Al-CO₃^2- can be well described by the pseudo-second order model. The adsorbed quantities of nitrates at equilibrium is about 33 mg per unit mass of Mg-Al-CO₃