Otimização da síntese de compósitos à base de TiO2 e carvão ativado e da remoção de hormônios estrogênios em água

Abstract

The removal of estrogenic hormones as contaminants of aqueous matrices is fundamental due to their negative impacts on aquatic ecosystems and human health. This study uses an advanced strategy to evaluate the efficiency of the combination of sortive and photocatalytic processes in the simultaneous removal of four estrogens: estrone (E1), 17β-estradiol (E2), 17α-ethinyl estradiol (EE2) and levonorgestrel (LEVO) from water. Compounds formed by nanoparticles of titanium dioxide (TiO2) and commercial activated carbon were tested and the most efficient removal of contaminants was selected based on the experimental design (DoE) of the central rotary compound design (DCCR) for process optimization. The composites were initially synthesized with activated carbon mass ratio (AC) varying from 2.93% to 17.07% (peso) and calcination temperatures between 259 °C and 541 °C. From an initial concentration of 100 μg L -1 of two four hormones in ultrapure water, the composite formed by 15% of AC and calcined at 541 °C (TiO2 -AC15%-541) was more efficient, promoting high rates of removal of estrogens under UV-A irradiation, namely: 98.3 ± 1.15% for E1, 99.0 ± 1% for E2, 99.3 ± 1.15% para EE2 e 96.0 ± 2.65% para LEVO. Through the DCCR, the following levels for three independente variables (pH 2.64, hormone concentration of 380 µg L-1, and UV-A radiation intensity of 41 W m-2) resulted in higher hormone removal rates, namely: 99.8% for E1, 99.8% for E2, 99.0% for EE2 and 92.1% for LEVO. The results highlight the effectiveness of the TiO2-AC15%-541 composite treatment in view of the energy required to remove estrogen hormones in a water mixture, demonstrating great potential for real-scale applications.