Removal of emerging pollutants by an adsorbent developed from a waste produced in a thermoelectric power plant: adsorption and ecotoxicological studies

The increasing use and improper disposal of pharmaceuticals have caused significant environmental impacts. Conventional treatment methods face challenges at the industrial scale, whereas abundant, low-cost adsorbents such as residues offer a sustainable alternative for pharmaceutical removal. In this study, an adsorbent was developed from sludge generated by the water treatment system of a thermoelectric power plant. The precursor was chemically modified with dodecyltrimethylammonium chloride (DTAC) and designated as chemically modified residue (CMR). The CMR was applied for the removal of ibuprofen, sodium diclofenac, and potassium losartan from aqueous solutions. Characterization was performed using SEM, FTIR, XRD, TG, nitrogen adsorption–desorption, PZC, XRF, CHN, and XPS. XRF revealed Si, Al, and Fe as the predominant elements. XPS analysis identified surface chemical bonds including C–C, C–OH, C–O–C, Si–C, and nitrogen species. FTIR analysis revealed vibrational bands associated with Si–O–Si, Si–O–Al, Si–O, Si–OH, and CH₂. XRD identified crystalline phases such as SiO₂ and NaAlSi₃O₈. Modification with DTAC led to an improvement in removal efficiency, with values exceeding 70.00 %. The maximum experimental adsorption capacities were 101.43 mg g⁻¹ for losartan, 73.77 mg g⁻¹ for diclofenac, and 24.81 mg g⁻¹ for ibuprofen, demonstrating the system's potential to remove these compounds. Ecotoxicity tests using pharmaceutical solutions resulted in EC₅₀,_48h values of 24.11, 175.50, and 53.92 mg L⁻¹ for diclofenac, losartan and ibuprofen, respectively. These results demonstrate that CMR is an effective and low-cost adsorbent for pharmaceutical removal, promoting waste reuse and reducing environmental impact.