Removal of carbamazepine and diclofenac at trace levels from water using a regenerable polymeric adsorbent and a desorption-based analytical method

This study explores the potential of a commercial, chemically unmodified, and milled thermoplastic polyester elastomer (MTPEE) for the first time as an adsorbent for the removal of diclofenac and carbamazepine from ultrapure water and a municipal wastewater treatment plant effluent. A desorption-based analytical method was developed to assess adsorption at environmentally relevant, low initial pharmaceutical concentrations by quantifying the total amount of pharmaceuticals recovered from the polymer after adsorption. In both water matrices, adsorption data were best described by the Langmuir isotherm, which indicates monolayer adsorption, while kinetic modeling showed a faster adsorption rate for carbamazepine. Besides, the polymer showed excellent regeneration capability and maintained the adsorption efficiency constant over six consecutive cycles. Testing the influence of four major wastewater constituents on pharmaceuticals´ adsorption revealed their negative effect on adsorption, particularly for diclofenac, except for NaCl. These findings were consistent with results obtained in wastewater treatment plant effluent, where diclofenac adsorption was strongly suppressed, whereas carbamazepine adsorption was less affected. Although diclofenac exhibited higher adsorption capacity, affinity, and selectivity than carbamazepine in ultrapure water, the complex wastewater effluent matrix significantly altered selectivity, favoring carbamazepine adsorption. Overall, the results demonstrate the potential of a simple, non-porous commercial adsorbent to enable more sustainable micropollutant removal due to its recyclability, even if selectivity is partially compromised in wastewater matrices. • MTPEE effectively adsorbed diclofenac and carbamazepine in water and wastewater • Desorption-based method enabled adsorbent performance analysis at low pharmaceutical levels • Adsorption followed Langmuir monolayer behavior with faster kinetics of carbamazepine • MTPEE showed constant regenerability over six adsorption-desorption cycles • Wastewater matrix suppressed diclofenac adsorption and shifted selectivity toward carbamazepine