Heterogeneous Catalytic Ozonation of Aniline-Contaminated Waters: A Three-Phase Modelling Approach Using TiO2/GAC

Cristian Ferreiro,José Ignacio Lombraña,María J Rivero,Natalia Villota

doi:10.3390/w12123448

Abstract

This work aims to study the sustainable catalytic ozonation of aniline promoted by granular active carbon (GAC) doped with TiO2. Aniline was selected as a model compound for the accelerator manufacturing industries used in the manufacture of rubber due to its environmental impact, low biodegradability, and harmful genotoxic effects on human health. Based on the evolution of total organic carbon (TOC), aniline concentration measured using high performance liquid chromatography (HPLC), pH and ozone concentration in liquid and gas phase, and catalyst loading, a three-phase reaction system has been modelled. The proposed three-phase model related the ozone transfer parameters and the pseudo-first order kinetic constants through three coefficients that involve the adsorption process, oxidation in the liquid, and the solid catalyst. The interpretation of the kinetic constants of the process allowed the predominance of the mechanism of Langmuir–Hinshelwood or modified Eley–Rideal to be elucidated. Seven intermediate aromatic reaction products, representative of the direct action of ozone and the radical pathway, were identified and quantified, as well as precursors of the appearance of turbidity, with which two possible routes of degradation of aniline being proposed.

Highlights

At present, as part of corporate social responsibility, manufacturing industries must compromise in the short-term in order to carry out environmental protection actions
The use of high doses of ozone limits the kinetics and adsorption capacity of aniline and its degradation oxidation products, with oxidation in the liquid being the principal route of degradation
At moderate ozone doses, a greater role of the adsorption and oxidation mechanisms of the TiO2 deposited in the granular active carbon (GAC) was observed

Summary

Introduction

As part of corporate social responsibility, manufacturing industries must compromise in the short-term in order to carry out environmental protection actions. The removal of aniline, as a model pollutant of environmental concern, is studied. Is mainly used in the synthesis of methylene diphenyl isocyanate to produce polyurethane foams, antioxidants, activators, and accelerators in the rubber industry, as well as in the synthesis of indigo and other dyes [3]. It is employed as a raw material in the manufacturing of different types of fungicides in the agricultural and pharmaceutical industries [4,5]

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