DEGRADAÇÃO FOTOCATALÍTICA DE 4-NITROFENOL EM SUSPENSÃO AQUOSA DE NANOPARTÍCULAS DE TiO2 SINTETIZADO VIA ANODIZAÇÃO ELETROQUÍMICA

Abstract

4-Nitrophenol (PNP) is an organic pollutant that poses significant risk to the public and environment, due to their bioaccumulative potential health risk, and mutagenicity or carcinogenicity. Since titanium dioxide (TiO2) promotes the oxidation of organic pollutants, TiO2 nanoestructured powders were prepared to evaluate the effects of drying (PO1E) or heat treatment (PO1EF and PO1F) to improve their ability to PNP photocatalytic decomposition. The experimental procedure was performed in two stages: TiO2 powders synthesis and their photocatalytic activity characterization under UV, fluorescent light and in absence of light to PNP decomposition. Powder morphological and chemical characterization were performed using Scanning Electron Microscopy Field Emission Gun (SEM-FEG) coupled to Energy-Dispersive X-ray Spectroscopy (EDX). Structural characterization was obtained by XRD (X-ray Diffraction. For photocatalysis tests, PNP aqueous solutions at concentration of 25mg L-1 were prepared. UV-vis spectrophotometer was used to establish the maximum and minimum absorbance (%) limits measured at 405 nm. The powders were present as agglomerated nanosized particles to form a porous structure, being sintered after heat treatment at 450 °C/1 h. All anodized powders were in the anatase phase, with nanometric sizes ~ 50 nm and varyin micron sizes between 0,2 and 50 micrometers. UV illumination was three times more efficient than fluorescent light in PNP decomposition, and P25 catalyst (reference material) the better in both cases. Among anodized powders, PO1E was most promising in PNP decomposition. PO1EF presented the better adsorptive capacity between analyzed powders.