Sorption of Ag+ and Cu2+ by Vermiculite in a Fixed-Bed Column: Design, Process Optimization and Dynamics Investigations

Vermiculite has been used for the removal of Cu2+ and Ag+ from aqueous solutions in a fixed-bed column system. The effects of initial silver and copper ion concentrations, flow rate, and bed height of the adsorbent in a fixed-bed column system were investigated. Statistical analysis confirmed that breakthrough curves depended on all three factors. The highest inlet metal cation concentration (5000 mg/dm(3)), the lowest bed height (3 cm) and the lowest flow rate (2 and 3 cm(3)/min for Ag+ and Cu2+, respectively) were optimal for the adsorption process. The maximum total percentage of metal ions removed was 60.4% and 68.7% for Ag+ and Cu2+, respectively. Adsorption data were fitted with four fixed-bed adsorption models, namely Clark, Bohart-Adams, Yoon-Nelson and Thomas models, to predict breakthrough curves and to determine the characteristic column parameters. The adsorbent was characterized by SEM, FTIR, EDS and BET techniques. The results showed that vermiculite could be applied as a cost-effective sorbent for the removal of Cu2+ and Ag+ from wastewater in a continuous process.