APLICAÇÃO DE PROCESSOS FOTO-FENTON NA DEGRADAÇÃO DE EFLUENTES INDUSTRIAIS UTILIZANDO MEMBRANAS DE ACETATO DE CELULOSE/Fe

Abstract

In this work, the degradation of organic pollutants was investigated by the photo-Fenton process using immobilized forms of Fe3+ in cellulose acetate membranes. Two membranes were prepared with different iron concentrations (CAFe 1% and 5% (w/w), which were characterized by atomic absorption spectrometry, electron spectroscopy in the ultraviolet and visible (UV-VIS), infrared spectroscopy (FTIR) chemical mapping by energy dispersive X-ray spectrometry (EDS), thermal gravimetric analysis (TG/DTA). The iron chemical mapping showed homogeneity in the metal surface of the prepared membranes, without agglomeration thereof. In the FTIR spectrum were observed two bands in the region of 875 and 838 cm-1, associated with the fixed iron, since they were not found in pure cellulose acetate. The performance of the prepared membranes were tested solutions by degradation of the azo dye Reactive Black 5 and Phenol (50 mg L-1), and further analysis of real effluent. The variables affecting the photo-Fenton process, such as iron concentration in the membranes of cellulose acetate, hydrogen peroxide concentration and pH of the solution were optimized using factorial design 23. Membranes prepared with higher amounts of iron resulted in better results in a pH = 4,0. The optimum amount of hydrogen peroxide for dye was 100 mg L-1 and the phenol 140 mg L-1. For both substrates models in studies using artificial light, degradation was approximately 100% and an average 89% reduction of chemical oxygen demand (COD). As expected, processes solar radiation were less effective than those operated by artificial radiation, in this case, 78% of COD reductions were obtained for the dye and 83% for phenol. In the process operated at pH 6,0 and artificial light, the degradation of these substrates was very similar to that obtained at pH 4,0; indicating that the membranes can be used at more basic pH without precipitation of iron ions. Studies of adsorption and photocatalytic decomposition of hydrogen peroxide, showed little influence on the degradation of substrates when compared with the excellent results obtained by the photo-Fenton process. In all studies, it was observed that the iron remained fixed and stable membranes, enabling the reuse of the material up to seven times. Regarding the application of the process in the degradation of industrial effluents, it was checked again the catalytic efficiency of the material prepared as in times of 300 minutes there was a reduction of approximately 70% of COD in the effluent of the toilet paper industry and 72% of COD to the effluent from the textile industry.