Degradação oxidativa da fluoxetina utilizando rejeitos de mineração como catalisadores

Abstract

Fluoxetine (FLX) is one of the most prescribed antidepressants in the world, and it can be found improperly in water, and it can affect organisms in a harmful way. One of the ways to reduce the presence of this organic contaminant is with the use of Advanced Oxidative Processes, since conventional wastewater treatments cannot eliminate this type of micropollutant. There is also a growing concern in the reuse of industrial waste, in order to reduce their environmental impact. Iron mining tailings (named after residues) have properties suitable for use as catalysts in the oxidation of drugs and other organic pollutants, from the Fenton process, with hydrogen peroxide, an oxidizer that can generate hydroxyl radicals and water as by-products. Another pollutant found in water is PET bottles, but this powdered residue can be used as a support with mining tailings, with similar or even superior results in the degradation of organic compounds. Thus, the objective of this work was to study the degradation of fluoxetine by a heterogeneous Fenton and Fenton-like process, using mining tailings (containing iron and silica), in addition to the association with the PET polymer residue (mixture of the two residues), comparing commercial iron II and III salts (homogeneous process, faster, but more expensive). Mining solids were characterized by FTIR spectroscopy, nitrogen gas adsorption and desorption, TG-DTA-DSC, XRD and SEM. The analyzes of the FLX concentration were determined by High Performance Liquid Chromatography (HPLC). The greatest degradation of FLX was obtained with the mining tailing associated with PET (lower iron content), with results of up to 81% of degradation, being better compared to the crude and concentrated samples, with higher iron contents (maximum degradation) 37%), suggesting the potential for applying these residues as catalysts, since they have lower costs than homogeneous catalysts, generate less iron ions in the solution, and can be easily recovered and reused. In these conditions, there was adsorption, avoiding the formation of degradation by-products that can be more toxic than the pollutant itself, and degradation, which can even mineralize the pollutant. To find the best ratio between the catalyst mass and the oxidant volume, the Central Compound Rotational Design (CCRD) statistical tool was used, showing that the largest catalyst mass used from the PET mining residue (45 mg) and the greater volume of oxidant (490 μL) is closer to the point of optimization of the degradation of FLX with hydrogen peroxide.