The use of alternative catalysts in processes of the chemical degradation of di-n-butyl phthalate in aqueous solutions

Abstract

The work detailed here investigated the efficiency of oxidising technologies in clearing aqueous solutions of di-n-butyl phthalate (DBP), a known endocrine-disrupting compound (EDCs). Specifically, this paper addresses the use of the classic Fenton process, and the development of a modification of Fenton's reagent targeted at the degradation of di-n-butyl phthalate in aqueous solution. The modification in question entailed the use of alternative catalysts or a mixture thereof. Hence oxidation by hydrogen peroxide (at various different concentrations), the classic Fenton process, was tested for the removal of DBP, alongside versions modified in terms of the quantitative and qualitative composition of a mixture of catalysts, and the presence of metal ions, as well as the factors of time, pH and initial DBP concentration. Given that it did not exceed 31%, the degradation of DBP we achieved using H₂O₂ could not be regarded as satisfactory. In contrast, the addition of 2.5 mM L^-1 of Fe²⁺ was found to mediate almost complete elimination of the phthalate from the model solution. Also confirmed by experimentation were the benefits of using homogeneous catalysts (compounds of copper(II) and manganese(II)) as alternatives to Fe²⁺ in the Fenton reagent. A key experimental achievement was to confirm the applicability of a catalyst formed from a mixture of 2 or 3 types of transition metal ion. A Fenton reaction extended to ions like Mn²⁺ and Cu²⁺ in particular is seen to eliminate factors/parameters discouraging practical industrial use of the classic Fenton process.

Keywords: Advanced oxidation processes; Alternative catalysts; Catalyst mixtures; Di-n-butyl phthalate; Modified Fenton process.