Aplicação de sistemas aquosos bifásicos para extração de contaminantes emergentes e estudo da eficiência de remoção em etapas do tratamento de água

Abstract

Emerging contaminants are a class of compounds persistent in the environment, consisting of pharmaceuticals, pesticides, illicit drugs, hormones, flame retardants, surfactants, among others, which are not eliminated from the environment by conventional treatments of water bodies and cause effects on aquatic organisms. The aqueous two-phase system (ATPS) is a liquid-liquid extraction technique based on the precepts of green chemistry, which has also been used for the extraction of trace compounds. In this study, the proposal is to use ATPS as a sample preparation technique for the determination of five pharmaceuticals: ibuprofen, paracetamol, ciprofloxacin, norfloxacin and amoxicillin. The evaluation of this study was performed through the partition coefficient (K) of each pharmaceutical by varying some factors of the system, such as: the pH value of the medium, ATPS-forming electrolyte and the polymer, the tie-line length (TLL), the system temperature and the mass ratio between the bottom and top phases of the ATPS. Values of K between 9.3 and 1x103 were obtained for the five pharmaceuticals studied in aqueous solution. The ATPS also proved to be efficient (K between 2.5 and 74.2) in the partition of the studied pharmaceuticals when applied to drinking water, surface water and filtered water from a water treatment plant. The removal of these pharmaceuticals in raw water was studied by simulating the main steps of a water treatment, such as: pre-oxidation, pre-alkalinization, coagulation/flocculation, decantation, filtration, and disinfection. The filtration and pre-alkalinization steps were the most efficient for the removal of the studied pharmaceuticals.