Treatment of Drug Residues From Waters: Effect of Surfactants and Regeneration Through Solvent Desorption

In this study, the adsorption behavior of pharmaceutical compounds such as promethazine, triflupromazine, trimethoprim, carbamazepine, and ibuprofen on activated carbon in aqueous media was investigated. The effects of ionic surfactants (sodium dodecyl sulfate and dodecyl trimethyl ammonium bromide) on this process were also evaluated. The effects of parameters such as contact time, initial concentration, and temperature on adsorption efficiency were systematically investigated. Lagergren first‐order and pseudo‐second‐order models were applied in kinetic analyses; the results obtained showed better fit to the pseudo‐second‐order model. The Giles curves obtained from isotherm studies exhibited an L‐shaped character, and the equilibrium data fit the Langmuir model better than the Freundlich isotherm. The calculated adsorption capacities followed the order ibuprofen > carbamazepine > trimethoprim > triflupromazine > promethazine. The presence of surfactants did not alter the equilibrium time but significantly affected the adsorption capacity. Furthermore, the desorption of promethazine from activated carbon was studied using low molecular weight alcohols (methanol, ethanol, and isopropanol); the highest desorption rate was obtained with a solution containing 40% isopropanol in 24 h. Successive adsorption–regeneration cycles were successfully performed under these conditions.