Experimental Design and Optimization of Triclosan and 2.8-Diclorodibenzeno-p-dioxina Degradation by the Fe/Nb2O5/UV System

Michel Fidelis,Onélia Dos Santos,Rodrigo Brackmann,Daniele Dias,Eduardo Abreu,Giane Lenzi,Eduardo Chaves

doi:10.3390/catal9040343

Abstract

This study describes the experimental design and optimization of the photocatalytic reaction using the immobilized catalyst Fe/Nb2O5 in the degradation of Triclosan and 2.8-DCDD. The techniques employed to characterize the photocatalysts were: specific surface area, average pore volume, average pore diameter, photo-acoustic spectroscopy (PAS), X-ray diffraction (XRD), and scanning electron microscopy (SEM/EDS). The reaction parameters studied were pH, catalyst concentration, catalyst calcination temperature, and nominal metallic charge. The results indicated that the immobilized Fe/Nb2O5 catalysts were efficient in the degradation of Triclosan and 2.8-dichlorodibenzene-p-dioxin. The catalysts with nominal metal loading of 1.5% Fe calcined at 873 K showed the highest constant reaction rate and the lowest half-life 0.069 min−1 and 10.04 min. Tests in different matrices indicated that the photocatalytic reaction using aqueous solution containing Cl− is faster when compared with the ultrapure water matrix.

Highlights

The chemical compounds progressive use, coupled with the low efficiency of effluent collection and treatment systems, have contributed to the significant increase in contaminants of emerging concern found in surface waters
These results indicate the influence of the calcination temperature and the addition of Fe
The Fe/Nb2 O5 immobilized catalysts were efficient in the Triclosan and 2,8-dichlorodibenzenep-dioxin degradation

Summary

Introduction

The chemical compounds progressive use, coupled with the low efficiency of effluent collection and treatment systems, have contributed to the significant increase in contaminants of emerging concern found in surface waters. This was considered to be of low risk to the environment, and these contaminants were detected only a few years ago. Among the contaminants of emerging concern is the Triclosan (TCS) and 5-chloro-2-(2,4dichlorophenoxy)-5-phenol—an antimicrobial agent that is extensively used as a preservative in a variety of consumer products such as toothpaste, antiseptic soaps, detergents, cosmetics, plastic kitchenware, socks, rugs, and toys [1,2,3]. Exposure to radiation, mainly in an environment with free chlorine, favors the reaction of transformation of the TCS in this compound [6,7]

Methods

Results

Conclusion