Continuous Fixed-Bed Column Study and Adsorption Modeling for Cadmium Removal

Adsorption of cadmium ions from aqueous solutions using granular activated carbon prepared from Phosphoric acid treated tamarind nuts (seeds) in fixed bed column was investigated. Activated carbon granules of 300 to 800µm particle size were chosen for all studies. The effect of metal ion concentration (50-200 mg/L), feed flow rate (5-15 mL/min) and activated carbon bed height (10-20 cm) on the breakthrough characteristics of the adsorption process were determined. The results showed that the adsorption efficiency increased with increase in influent concentration, bed depth and decreased with increase in flow rate. Column adsorption data were fitted to three well established fixed bed adsorption models namely Adam’s-Bohart, Thomas and Yoon-Nelson models. The results fitted well to Thomas and Yoon-Nelson models with coefficients of correlation R2≥ 0.9 at different working conditions. Phosphorylated tamarind nut carbon (PTNC) was proved to be suitable for adsorption of cadmium from aqueous solutions using fixed-bed adsorption column.