Heavy metal removal and water treatment using Upsalite

Abstract: Ion exchange reactions between Upsalite, a mesoporous magnesium carbonate, and metal ions of cadmium, lead and nickel have been studied to evaluate the capacities of Upsalite as a water treatment agent. Uptake capacity and reaction kinetics have been evaluated using a batch experiment and atomic absorption spectroscopy. Post reaction materials from the reaction between Upsalite and each of the three metal ions have been investigated with XRD, SEM and TGA in order to determine what species have been formed during the ion exchange.   The maximum uptake capacity of Upsalite was found to be 990 mg/g for cadmium ions and 470 mg/g for nickel ions. The evaluation of the uptake capacity of lead ions in Upsalite was not conclusive but the results indicate a maximum uptake capacity of at least 4400 mg/g. The uptake capacity for lead ions is to high be explained by ion exchange alone and is proposed to be from both ion exchange and adsorption. The reaction between Upsalite and cadmium ions resulted in the formation of crystalline CdCO3 (Otavite) with some parts of MgCO3 and crystalline MgO remaining from the original material. Post reaction materials from the reaction between nickel ions and Upsalite were found to be amorphous and contained both MgCO3 and crystalline MgO. The reaction between Upsalite and lead ions resulted in crystalline hydrocerussite (Pb3(CO3)2(OH)2).