Abstract
Adsorption is currently recognized as an efficient and economical process for the treatment of toxic metals from wastewater. This process provides flexibility in the design and operation of treatment systems and in many cases generates a high-quality treated effluent. Furthermore, due to the reversibility of the adsorption adsorbents are sometimes regenerated by desorption suitable. Among the adsorbent materials, clays are characterized by their wide availability and low cost, which aggregates the potential they represent, especially when modified, resulting in scientific and industrial interest. Bentonite or smectite clays are widely used in industry, where applications are associated with their characteristic adsorbent and these properties can be improved by thermal and chemical treatments. Copper sorption behavior of calcined Bofe clay in consecutive adsorption–desorption cycles has been investigated in a packed-bed flow-through column during a continuous removal of copper from a 1.57 mmol/L aqueous solution at pH 5. The eluent used was HCl 0.1 mol/L. The adsorption and desorption were carried out for an average of 15 and 4 h, respectively, representing more than 2 days of continuous use of the adsorbent. The weight loss of mass after this time was 0.6 %. The Cu-sorption capacity of the calcined clay, based on the initial dry weight, was approximately 0.11 mmol/g. Sorption performance was indicated by shortening breakthrough time and a broadening mass-transfer zone. The column useful time, considered up to 1 mg Cu/L in the effluent, keeping aproximately in 100 min for all cycles. The mass-transfer zone, decreased almost linearly from 10 to 9 cm. Regeneration with HCl provided elution efficiencies up to 100%.
