Medicamentos psicoativos em matrizes aquosas: ocorrência e remoção pela fotocatálise mediada por TiO2 e compósito TiO2/carvão ativado

Abstract

Population growth, coupled with growing demand for chemicals and pharmaceuticals, including packages, detergents, pesticides, pharmaceuticals compounds and personal care products, have led to an increasing presence of emerging contaminants in different environmental compartments. Psychoactive pharmaceuticals, such as anxiolytic and antidepressant drugs, are widely prescribed worldwide and are considered as emerging environmental contaminants. Such drugs have already been detected in different water matrices in different parts of the world, including Brazil. In addition, many of these compounds are not readily degraded and not totally removed by conventional sewage and water supply treatment plants. There is evidence that some Advanced Oxidation Processes AOPs can be applied to degrade these drugs in water, reaching high efficiency or even total removal. The general objective of this study is to assess the efficiency of the treatment by heterogeneous photocatalysis using as catalyst titanium dioxide (TiO2) commercial and composite of TiO2-activated carbon, both in suspension and impregnated in glass beads for the removal of anxiolytic drugs belonging to the benzodiazepine family in ultrapure water at environmentally relevant concentrations. The objectives of this investigation were: (i) to assess the occurrence of psychoactive drugs in different aqueous matrices, levels of contamination and removal achieved by conventional treatment plants, based on records in the literature; (ii) to assess the ecotoxicity pose by these drugs on aquatic bioindicators, based on records in the literature; (iii) to develop and apply commercial TiO2 immobilized onto glass beads in heterogeneous photocatalysis for photoactivity, characterization, leaching and regeneration studies; (iv) to synthesize and characterize the composite formed by TiO2/activated carbon for application in heterogeneous photocatalysis assays; (v) to assess the performance of TiO2 commercial catalyst and TiO2/activated carbon composite applied in suspension and impregnated onto glass beads in removing anxiolytic compounds (bromazepam, clonazepam and diazepam) from water. The literature review (219 articles and 1642 data/entries) about the occurrence in different aqueous matrices of seven psychoactive drugs, among which, six benzodiazepines (alprazolam, bromazepam, clonazepam, diazepam, lorazepam and oxazepam) and one antidepressant (citalopram) showed that drug concentrations in all aqueous matrices investigated ranged from 0.14 to 840,000 ng/L. Among TiO2/activated carbon composites evaluated, the one with 10% by weight of activated carbon (TiO2/AC10%), presented a synergistic effect between TiO2 and activated carbon, which promoted superior performance in the removal of target compounds (bromazepam, clonazepam and diazepam) when compared to commercial TiO2 separately in photocatalysis applications with the catalyst suspended or impregnated onto glass beads, even after several treatment cycles. Thus, the TiO2/AC10% composite can be considered an attractive alternative material to the use of the commercial TiO2-P25 catalyst for water/wastewater treatment and polishing applications