Water Contaminated by Industrial Textile Dye: Study on Decolorization Process

Pierantonio De Luca,Jànos B Nagy,Anastasia Macario,Paola Foglia,Carlo Siciliano

doi:10.3390/environments6090101

Pierantonio De Luca, Jànos B Nagy + Show 3 more

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https://doi.org/10.3390/environments6090101

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Journal: Environments	Publication Date: Sep 2, 2019
Citations: 15	License type: CC BY 4.0

Affiliation: University of Calabria

Abstract

This work aims to investigate possible interferences due to the presence of sodium carbonate on the photodegradation of the reactive Black 5 azoic dye, both in systems containing only titanium oxide and those containing titanium oxide and hydrogen peroxide. The role of hydrogen peroxide is explicitly treated. Sodium carbonate, in fact, is often present in the wastewater of textile industries as it is used in the fiber dyeing phases. The use of TiO2 nanoparticles is emphasized, and the possible danger is underlined. Each system was subjected to ultraviolet irradiation (UV) by varying the exposure time. After the photodegrading tests, the resulting solutions were analyzed by UV-vis spectrophotometry and High-Resolution Nuclear Magnetic Resonance to measure the residual concentrations of dye. The dye degradation curves and reaction rates for different UV exposure times were obtained and discussed as a function of the used additives. All the data are repeated three times, and they differ only by a maximum of 5%. The results indicated a reduction of about 50% of the initial concentration of Reactive Black 5 after 30 min under optimal experimental conditions. The NMR analysis indicated the formation of a series of aromatic structures that were generated by the UV-induced photochemical fragmentation of the original molecule.

Highlights

There are already many polluting substances that put the environment and human health at risk [1,2,3,4,5,6]
From the set of results obtained, it is clear that the Reactive Black 5 azo dye in the absence of photocatalytic agents is fairly photostable; after thirty minutes of ultraviolet irradiation (UV) radiation, a reduction of only 8.9% is recorded
Titanium oxide instead plays a fundamental role in the UV-induced photodegradation of Reactive Black 5 azo dye, and the photocatalytic activity of titanium dioxide can be improved through the simultaneous use of hydrogen peroxide

Summary

Introduction

There are already many polluting substances that put the environment and human health at risk [1,2,3,4,5,6]. Alongside the development of new materials, particular interests have been turned to the study of eco-friendly processes designed to purify the wastewater using sunlight, a renewable and clean energy. In this “pro environment” context, the photochemistry is having a great development through the application of photocatalysis, a natural phenomenon that is manifested by a chemical reaction that mimics the photosynthesis of plants to absorb and transform pollutants into harmless elements [12,13,14,15,16,17]. In the presence of specific substances called photocatalysts. One has tried to widen the range of substances that may be used as photocatalysts, and among the new species there are the zeolitic materials [21,22,23,24,25,26,27,28,29], and adsorption materials such as microporous materials and carbon nanotubes [30,31,32,33,34,35,36]

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