Abstract
It is well known that water treatment of printing and dyeing wastewaters is problematic. In order to decompose dyes from dyestuff wastewater and convert them into almost harmless substances for the natural environment, an easily prepared, efficient, practical, and easy-to-regenerate composite material was produced from porous floating ceramsite loaded with cuprous oxide (PFCC). The PFCC samples were prepared and characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The material was applied for photocatalytic degradation of methyl orange (MO) in water. The results show that the maximal degradation rate of MO was 92.05% when the experimental conditions were as follows: cuprous oxide loading rate of 8%, PFCC dosage of 20 g/L, the reaction time of 2 h, pH value of 8, and solution initial concentration of 30 mg/L. The degradation processes of MO fits well with the Langmuir–Hinshelwood model in reaction kinetics, and the Freundlich model in reaction thermodynamics, respectively. The degradation mechanism of MO was considered from two perspectives—one was the synergetic effect of adsorption and photocatalytic oxidation, and the other was the strong oxidation of hydroxyl radicals produced by photocatalysts.
Highlights
China is the world’s largest country in terms of the production and consumption of dyes, as well as the amount of dye and printing wastewater, and pollution from dyeing wastewater is continuing to increase [1,2]
Unlike raw ceramsite, the loaded ceramsite had more redundant and stronger peaks. Both of them had partial diffraction peaks aligned with those of cuprous oxide, this was more obvious in the loaded ceramsite, especially at 36.40◦ and 42.28◦
It might be that the low loading of cuprous oxide on the surface of the loaded ceramsite resulted in the cuprous oxide having indistinct peaks
Summary
China is the world’s largest country in terms of the production and consumption of dyes, as well as the amount of dye and printing wastewater, and pollution from dyeing wastewater is continuing to increase [1,2]. Dye wastewaters are emitted in large volumes, and they are distinguished by high chroma and complex chemical composition, and they are not suitable for effective biochemical degradation. The main methods for the detection of pollutants in this type of wastewater are BOD (biochemical oxygen demand) analysis, COD (chemical oxygen demand) analysis, determination of organic toxic substances, and chromaticity [3,4]. Dye and printing wastewater often use filtration, precipitation, coagulation, and physicochemical methods [5]. Photocatalytic oxidation degradation of dye wastewater is a recent research hotspot [6,7]. Studies have shown that using TiO2, ZnO, CdS, etc., as photocatalysts can effectively degrade organic substances such as dyes in wastewater [8]. There are relatively few studies on using cuprous oxide as a photocatalyst [9]
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