Visible-Light-Driven Reduced Graphite Oxide as a Metal-Free Catalyst for Degradation of Colored Wastewater

Mahmoud Mazarji,Tatiana Minkina,Svetlana Sushkova,Niyaz Mohammad Mahmoodi,Saglara Mandzhieva,Tatiana Bauer,Alexander Soldatov,Gholamreza Nabi Bidhendi

doi:10.3390/nano12030374

Abstract

Reduced graphite oxide (rGO)-based materials have demonstrated promising potential for advanced oxidation processes. Along with its distinctive 2D characteristics, rGO offers the prospect of catalytic degradation of various kinds of organic pollutants from aqueous environments. The practical application of rGO as a metal-free catalyst material to promote the Fenton reaction depends on the degree of rGO reduction. In this regard, the rGO was prepared according to oxidation by modified Hummers’ method and two-step reduction via hydrothermal and calcination in the N2 atmosphere. The as-prepared rGO was characterized in terms of X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, UV-vis absorption spectroscopy, and transmission electron microscopy. The effectiveness of as-prepared rGO as a photocatalyst and the metal-free catalyst to decolorize different textile dyes, including basic red 46, basic red 18, and methylene blue, was investigated in visible/rGO and visible/rGO/H2O2 systems. The impact of operational factors such as catalyst dose, pH, and initial dye concentration was examined. The dye degradation process was investigated by the pseudo-first-order kinetic model. In addition, the recyclability of rGO in the visible/rGO/H2O2 system was examined.

Highlights

The variety of organic dyes produced annually in different industries such as textile, paper, and plastic have been estimated to account for more than 450,000 tons globally [1].The fact that many of these dyes are constantly discharged into the environment as effluent throughout the manufacturing and application processes is an unpleasant side effect of their widespread usage, because their complex and synthetic origins are extremely hazardous, possibly carcinogenic, and mutagenic, posing a serious threat to human health and disrupting the ecosystem of receiving waterways [2,3,4,5,6,7]
Traditional water and wastewater treatment practices are inadequate to meet the difficulties associated with textile dyes [7,8]
The advances made by nanomaterials hold the promise of evolving traditional water and wastewater treatment technology to deal with environmental issues related to textile effluents [9,10,11,12]

Summary

Introduction

The variety of organic dyes produced annually in different industries such as textile, paper, and plastic have been estimated to account for more than 450,000 tons globally [1].The fact that many of these dyes are constantly discharged into the environment as effluent throughout the manufacturing and application processes is an unpleasant side effect of their widespread usage, because their complex and synthetic origins are extremely hazardous, possibly carcinogenic, and mutagenic, posing a serious threat to human health and disrupting the ecosystem of receiving waterways [2,3,4,5,6,7]. Photocatalytic and catalytic oxidation is well-known to be a promising and green technology in the field of advanced oxidation processes with high efficiency [13,14,15,16,17]. This process has been extensively investigated to mineralize a wide range of organic pollutants, including dyes, to relative nontoxic end products, i.e., water and carbon dioxide [9,11,18,19,20,21]

Methods

Results

Conclusion