High-performance removal of anti-inflammatory using activated carbon from water treatment plant sludge: fixed-bed and batch studies

A high-performance activated carbon from water treatment sludge was applied as adsorbent material to remove the anti-inflammatory Nimesulide from aqueous solution. The adsorption studies were performed in batch and fixed-bed systems, evaluating initial pH, adsorbent dosage, adsorption kinetics, equilibrium isotherm, continuous adsorption, and simulated effluents. The batch tests were carried out with the adsorbent dosage of 1 g L−1 and pH 8, previously determined by 22 Factorial Design. The kinetic data were best fitted to the Elovich model and Intraparticle diffusion reaching the equilibrium at 120 min. Langmuir model presented a better description of the equilibrium data with the maximum adsorption capacity of 274.99 mg g−1. The activated carbon from water treatment sludge was tested in two simulated hospital effluents and proved to be an excellent adsorbent, removing 98.57% of Nimesulide from aqueous solution containing salts, sugars, and other inorganics. The adsorbent was also applied in fixed-bed Nimesulide adsorption obtaining the satisfactory value of 217.28 mg g−1 for adsorption capacity. According to these results, activated carbon produced from water treatment plant sludge is one of the most competitive in the literature for Nimesulide removal. This innovation promotes a sustainable use for this residue, in addition to assisting the studies regarding the removal of pharmaceutical compounds present in aqueous solution which have been highlighted in recent years.