Síntese, caracterização e aplicação de fotocatalisadores derivados de dióxido de titânio e óxido de ferro III para a degradação do 2,4 – Diclorofenol®

Abstract

The contamination of our planet, with environmental pollutants generated by the excessive use of pesticides has grown year after year. The 2,4 – dichlorophenol® (2,4 – DF) is the main degradation by-product of 2,4 – dichlorophenoxyacetic acid (2,4 – D), a herbicide classified as extremely toxic, harmful to human health and with difficult degradation, which is currently in the 2nd place of most used pesticides in Brazil, with more than 6 tons of sales per year. With this extremely high use, conventional degradation methods are not able to fully mineralize the pollutant from the environment. As a proposed methodology to mitigate the effects of this contamination, this work aimed to synthesize photocatalysts based on iron III oxide and black titanium dioxide, with the aim of using them in heterogeneous photodegradations. The synthesized compounds were characterized using differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Degradation and kinetics tests of the pesticide 2,4 – DF were performed at a concentration of 2.2 x 10-4 mol L-1, with the three photocatalysts, iron oxide III, titanium dioxide and titanium dioxide black, in basic, acidic and neutral media. It was verified that the three particles had a photocatalytic effect and the complete mineralization of the pollutant in 4 hours, obtaining a cheap catalyst, of easy synthesis and effect. Therefore, among the photocatalysts studied, the iron oxide particle at basic pH obtained a faster degradation rate constant, with a value of 0.02859 min.-1 over a 60 minute timeframe.