Simultaneous removal of E1, E2, EE2 and levonorgestrel from water using TiO2 catalyst anchored on activated carbon: Processes optimization, materials characterization, and assessment of the estrogenicity reduction

Removal of estrogen hormones from water matrices is crucial owing to its adverse effects on aquatic ecosystems and human health. The present investigation applies an advanced approach to assess the effectiveness of combined processes (adsorption and visible-light-driven photo-degradation) for simultaneous removal of estrone (E1), 17 beta-estradiol (E2), 17 alpha-ethinylestradiol (EE2), and levonorgestrel (LEVO) in water, applying TiO2-activated carbon composite selected through design of experiment (DoE) for process optimization. Based on a central composite rotatable design (CCRD), composites were synthesized with percentages of activated carbon (AC) ranging from 2.93% to 17.07% (wt.) and calcination temperatures between 259 and 541 degrees C. The composite with the best performance TiO2-AC15%-541 (15% wt. AC, calcined at 541 degrees C), achieved a total removal of 98.3 +/- 1.15% for E1, 99.0 +/- 1% for E2, 99.3 +/- 1.15% for EE2, and 96.0 +/- 2.65% for LEVO at the initial concentration of 100 mu g L (-1) under simulated solar irradiation. Further optimization using once more CCRD involved three independent variables: pH; hormone concentration/TiO2-AC15%-541 loading ratio; and the intensity of simulated solar irradiation. Under optimized conditions (pH 2.64, hormone concentration/TiO2-AC15%-541 loading ratio of 3.8 mg g(-1), and irradiation intensity of 41 W m(-2) UV-A), the TiO2-AC15%-541 composite removed 99.8% of E1, 99.8% of E2, 99.0% of EE2, and 92.1% of LEVO. Furthermore, the process achieved a 99.9% reduction in estrogenic activity, assessed with yeast estrogen screen (YES) assay. These results demonstrate that TiO2-AC15%-541 is an efficient and cost-effective remediation agent for treating mixed estrogen compounds in water, with significant potential for commercial applications.