Removal of selected pharmaceuticals from aqueous matrices with activated carbon under flow conditions

摘要

Removal of three selected pharmaceuticals namely, diclofenac (DCL), naproxen (NPR) and carbamazepine (CRB) was investigated in aqueous matrices using fixed-bed columns packed with granular activated carbon (GAC) under flow conditions. Model individual, three-component solutions, model sewage water (MSW) and secondary sewage water (SSW) spiked with 5 mg L-1 of pharmaceuticals were studied. Effects of GAC amount (i.e., 4, 8, 12 g), flow rate (i.e., 40, 60, 100 mL min(-1)), and GAC particle size (i.e., 0.42-0.82, 0.82-1.0 and 1.0-1.7 mm) on the breakthrough curve were investigated. For each column bed, an adequate flow rate could be chosen for which the outlet-to-inlet concentration ratio (C C-0(-1)) remained below 0.05 for 20 L outflow volume. Above 1 mm particle size, the increase in the void volume decreased the efficiency of adsorption by 30-40%. The adsorption order of compounds changed from NPR > CBR > DCL to CBR > NPR > DCL for the single and the three-component model solutions, respectively. For the SSW, the adsorption order remained the same but its efficiency decreased by 15, 17 and 25% compared to the MSW for CRB, NPR and DCL, respectively, by applying the same conditions. Nevertheless, the removal efficiency in the optimal case for SSW was >= 95% and >= 80% at the mg L-1 and mu g L-1 concentration levels, respectively. The adsorption process was simulated for MSW and SSW by the Adams-Bohart and Thomas models.