Degradação do antibiótico tetraciclina em matriz aquosa por processos oxidativos avançados

Abstract

With the advancement of technologies, the productive capacity of the industries has increased considerably in the last decades, which has resulted in the insertion of new pollutants called emergent. Thus, such substances are found mainly in water. The proposal of treatment techniques aimed at mitigating these new pollutants is a fundamental step for the maintenance of water resources. For decontamination of these waters containing micropollutants the 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 (TCT) in synthetic aqueous matrix using the advanced oxidative processes (POAs) of photolysis (UV), homogeneous (H2O2/UV) and heterogeneous (H2O2/TiO2/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 batch system, consisting of several 250 mL containers, equipped with four mercury lamps of 15 W, of low pressure with the bulb. By means of the actinometry test it was obtained that the dose to the photoreactor after 20 minutes of assay is equal to 1.00x10-4 einstein s-1. The DCCR for photolysis indicated the best degration pH = 11 and [TCT] = 20 mg L-1. For homogeneous phototocatalysis, the best conditions were pH = 8.82, [TCT] = 20 mg L-1 and [H2O2] = 65 mg L-1. For heterogeneous phototocatalysis, the best conditions were pH = 5.5, [TCT] of 20 mg L- 1, [H2O2] = 50 mg L-1 and [TiO2] = 0,4g L- 1. By means of photolysis and heterogeneous photocatalysis, total removal of the antibiotic occurred after 240 minutes and for homogenous photocatalysis after 180 minutes. The kinetics of all treatments correspond to the pseudo first order model with K1 = 0.017min -1, for photolysis, K1 = 0.01 min-1 for homogeneous photocatalysis and K1 = 0.002 min-1 for heterogeneous photocatalysis. In the toxicity test with lettuce seed Lactuca Sativa L., a lower toxic effect was observed after all the degradation treatments used. The treatments of photolysis (UV), homogeneous (H2O2/UV) and heterogeneous photocatalysis (TiO2 / H2O2 / UV) are promising in the treatment of water and effluents contaminated with the TCT drug.