Effects of thermal treatment on feldspar sorptive properties: Identification of uptake mechanisms

Thermal treatments of two feldspars (FELA and FELB) have been performed in air at various temperature, ranging from 200°C up to 800°C. The influence of this heating on the efficiency of cadmium removal from aqueous solutions by immersing these two feldspars into these solutions is presented. Sorption tests carried out in batch-type reactors have demonstrated that cadmium removal efficiency of quenched minerals is strongly dependent on heating temperatures. Results of textural, structural and composition modifications due to heating are discussed combining several analytical techniques (BET, XRD, MEB-WDS and XPS). Effects of heating on sorption activity and exchange sites are valued on the basis of these data combined with direct measurements performed by ICP-AES on the species released from feldspar in aqueous solutions.