Kinetic modeling of lead removal in a resin column-parameters evaluation

Lead contamination of water streams, a potential threat to ecosystem, was treated using a cation exchange resin under continuous conditions in a upflow column. The optimal pH for maximum lead removal was identified through the batch experiments. Neutral pH was found to be favorable due to non-existence of competing hydrogen ions and absence of hydroxide containing precipitate formations. The effects of flow rates (4.0 to 8.0 mL/min) and the resin bed depth (6 to 18 cm) were studied under optimal pH and fixed initial lead concentration of 50 mg/L. The breakthrough curves were plotted and analyzed in detail. Bed Depth Service Time (BDST) and Thomas model were fitted to the experimental data and the model parameters were determined. The maximum exchange capacity of the bed (q(0)) was determined as 14.60 mg/g at a flow rate of 4 mL/min and a bed height of 12 cm and the Thomas model constant decreased with decrease in flow rate. BDST model parameters, namely, N-0 and Ka, increased with increase in flow rates. BDST proved to be a better fit compared to Thomas model under the entire range of operating conditions tested.