OXIDAREA FOTOCATALITICĂ OMOGENĂ ȘI ETEROGENĂ CU TiO2 / H2O2 ȘI Fe2 +/ H2O2 (REAGENTUL FENTON) A SURFACTANTULUI CATIONIC BROMURĂ DE CETILTRIMETILAMONIU

Veronica PORUBIN-SCHIMBĂTOR, Maria GONŢA, Larisa MOCANU Universitatea de Stat din Moldova

Abstract

PHOTO-CATALYTIC OXIDATION WITH TiO2 / H2O2 AND Fe2 +/ H2O2 (FENTON REAGENT) OF CATIONIC SURFACTANT CETYLTRIMETHYLAMMONIUM BROMIDE 

To prevent surfactant contamination of water and soil, the decrease of CTAB cationic surfactant in model systems has been studied by using photodegradation under UV/TiO2/ H2O2 and UV/Fe2+/H2O2 (photo-Fenton) conditions. In both processes, the factors influencing the effectiveness of photodegradation were evaluated. The residual concentration of the cationic surfactant was determined by UV/VIS spectrophotometry using methylene blue as a colouring agent and extraction. The research results showed that the concentration of the CTAB surfactant could be significantly reduced by using both UV/TiO2/H2O2 processes and UV/Fe2+/H2O2 processes with a degree of mineralization and degradation of about 50%. In both processes the dependence of the photodegradation efficiency of the surfactant on the physico-chemical parameters was observed: TiO2 concentration, Fe(II) and H2O2 concentrations, pH, time and wavelength. The homogeneous/heterogeneous photocatalytic oxidation reaction rates and the degree of mineralization were determined according to different physico-chemical parameters. It was found that the optimal pH for the oxidation of CTAB with photo-Fenton reagent is 2.5, and for the UV/TiO2/H2O2 system – 4.0. It is also confirmed that the UV/Fe2+/H2O2 process (photo-Fenton) was more efficient in the photodegradation of the CTAB surfactant than that of the UV/TiO2/ H2O2 process. 

Keywords: advanced oxidation, surfactant, CTAB, Fenton reagent, titanium dioxide, hydrogen peroxide, methylene blue, chloroform.