Fotocatálise heterogênea TiO2/UV para o tratamento de efluentes gerados na obtenção de membranas pela técnica de inversão de fases

Abstract

Among the technologies cleaner and research in water treatment, we highlight the Advanced Oxidative Processes (POA’s), which are based on the use of highly oxidizing species to promote a more effective degradation of the pollutant. In the present study, heterogeneous photocatalysis of titanium dioxide/Ultraviolet (TiO2/UV) was evaluated in the degradation of solvents N, N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP). The TiO2 semiconductor material was characterized by X-ray fluorescence (XFR), X-ray diffraction (XRD), infrared spectroscopy with Fourier transform (FTIR), particle size distribution, surface area, volume and average pore diameter , scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The effluents containing DMF and NMP were obtained from the precipitation bath generated in obtaining the membranes by the phase inversion technique. These organic effluents were evaluated by the following physicochemical parameters: hydrogen potential (pH), electrical conductivity, turbidity and chemical oxygen demand (COD). Independent operational variables such as pH, pollutant concentration (DMF and NMP) and photocatalyst load are directly related to the degradation capacity of the photocatalytic process and were evaluated by factorial design of experiments using the Statístic tool. According to the characterizations performed by FRX, DRX, FTIR, granulometric distribution, SEM, specific surface area, volume and average pore diameter, and by thermal analysis (DSC and TG) it was found that the TiO2 semiconductor had important and necessary intrinsic characteristics to be applied in photocatalytic processes. The kinetic tests were performed following the experimental planning and the kinetic data were adjusted to the pseudo-first order model. For the response of the photocatalytic degradation, all variables showed a significant effect at the 95% confidence interval. In addition, the Statístic tool detected that pH was the operational parameter that had the greatest influence and its relationship was directly proportional to the degradation of contaminants. Therefore, it was found that the heterogeneous TiO2/UV photocatalysis showed potential to be applied in photodegradation of solvents contained in effluents generated in obtaining membranes by phase inversion technique, obtaining a removal of up to 95% of the organic solvents DMF and NMP.