Estudo de degradação da tetraciclina em água empregando processos oxidativos avançados

Abstract

As a result of the growth of the world population, the consumption of medicines has increased significantly, which has resulted in the insertion of these pollutants into the environment, being found mainly in the waters. One of the groups of residual drugs that deserve attention is that of antibiotics because of their potential effect on the selection of resistant bacteria in the environment. The proposal of treatment techniques aimed at mitigating these new pollutants is a fundamental step for the maintenance of water resources. For the elimination of micropollutants in aqueous medium, Advanced Oxidative processes (POAs) have emerged as a promising technology due to their strong oxidizing power. The aim of this work was to study the degradation of the tetracycline antibiotic (TC) in synthetic aqueous matrix using (POAs) of homogeneous (photo-Fenton) and heterogeneous (TiO2/H2O2/UV) photocatalysis. The optimized conditions by means of full initial factorial design and later rotational central compound design (DCCR). The experiments were conducted in a laboratory scale reactor, with a batch system, consisting of four 250 ml containers, equipped with four 15 W low pressure mercury lamps with a wavelength of 254 nm. By means of the actinometry test it was obtained that the dose to the photoreator after 20 minutes of assay is equal to 1.00x10-4 Einstein s-1. The DCCR for homogeneous photocatalysis setting to [TC] = 20 mg L-1 was obtained as best conditions pH = 4, [H2O2] = 25 mg L- 1 and [Fe2+] = 15 mg L-1. For heterogeneous photocatalysis by setting [TC] = 20 mg L- 1, the best conditions were pH = 4, [H2O2] = 51 mg L-1 and [TiO2] = 0.23 g L-1. The kinetics data of the two treatments adjusted more satisfactorily to the pseudo-second order model with K2 = 0.002 min-1, for homogeneous photocatalysis and K2 = 0.0006 min-1 for heterogeneous photocatalysis. In the toxicity test with Escherichia coli as bioindicator microorganisms a lower toxic effect was observed after all the degradation treatments used. The homogeneous photocatalysis (photo-Fenton) and heterogeneous (TiO2/H2O2/UV) are promising in the treatment of water and effluents contaminated with the TC drug.