A facile strategy for the degradation of recalcitrant textile dyes using highly robust ZnO catalyst

Abstract

BACKGROUND Due to urbanization, the release of coloured wastewaters from textile industries into various environmental components has increased and is posing a threat to water bodies, so that their eradication from water bodies is necessary. To this end, semiconductor heterogeneous photocatalysis has emerged as a promising tool. However, as is well known, photocatalysis is a surface phenomenon; therefore it is strongly influenced by the fabrication technique employed for its synthesis. To address this issue, the present work demonstrates the dependence of synthetic methodology on photocatalytic efficacy of ZnO catalyst. RESULTS Catalytically active nanostructured ZnO particles were fabricated by five different facile methodologies. The fabricated nanostructures were critically analysed using techniques such as, X‐ray diffraction (XRD), high resolution transmission electron microscopy (HR‐TEM), Brunauer–Emmett–Teller (BET) and photoluminescence (PL) spectrophotometer. The photocatalytic activity of different ZnO catalysts was compared by using safranin O dye as probe molecule. CONCLUSIONS ZnO nanopowders fabricated by different methodologies were found to display different catalytic efficiencies, which was ascribed to large variations in specific surface area and rate of recombination of electrons and holes. Therefore, it is perceived that ZnO catalyst with best catalytic activity can be utilized to streamline the treatment of dye wastewater and is an ideal catalyst for a practical approach. © 2015 Society of Chemical Industry

Fe3+ @ ZnO/polyester based solar photocatalytic membrane reactor for abatement of RB5 dye

“…In a modern society, massive production and use of dyes has led to the generation and dumping of aqueous effluents containing 20% of dye contents (Kaur et al, 2016).The metabolites produced after the incomplete biodegradation of recalcitrant dyes are not only carcinogenic and mutagenic but also retard the photosynthetic activity of aquatic flora (Sarkar et al, 2012;Yu et al, 2017;Zhang et al, 2012).The azo dyes, characterized by having an azo group (-N=N-), are the largest class of dyes considered as persistent organic pollutants (POPs) of textile effluents (Bello et al, 2017;Kansal et al, 2007).All conventional protocols for the treatment of wastewater are categorized as physical, chemical and biological processes that have limitations regarding their execution and efficiency. The heterogeneous photocatalysis employing semiconductor metal oxides has been proved to have remarkable advantages such as mineralization of broad spectrum of pollutants even at ambient temperature and pressure (Asghar et al, 2015;Chow et al, 2017;Giannakis et al, 2017;Kannangara et al, 2018;Prieto-Rodriguez et al, 2012;Thompson and Yates, 2006;Zheng et al, 2017).…”

Equilibrium and Isotherm Studies on the Removal of Basic Textile Dye from Aqueous Solutions Using <i>Kigelia africana</i> Biosorbent

“…On the other hand, the complex structure of dyes made them to resist biodegradation and hence, it is inevitable to treat the dye effluents before releasing in to the environment. Different physical and chemical methods have been proposed such as ozonation, oxidation, adsorption, use of catalysts, photocatalysis, membrane filtration etc, to remove recalcitrant dyes from waste waters [3]. Among all the methods, adsorption on to activated carbon has received greater attention because of high efficiency [4].…”

Evaluation of the Photocatalytic Potential of TiO2 and ZnO Obtained by Different Wet Chemical Methods

“…Water contamination generated by dyes originating from the textile industries is a growing problem [1][2][3][4] since these pollutants typically show color and toxicity even in low concentration [5][6] . Several processes have been used to promote the water decontamination, among them physical and chemical processes.…”