Abstract
Degradation of organic dyes and their byproducts by heterogeneous photocatalysts is an essential process, as these dyes can be potentially discharged in wastewater and threaten aquatic and xerophyte life. Therefore, their complete mineralization into nontoxic components (water and salt) is necessary through the process of heterogeneous photocatalysis. In this study, Zr/CrO2 (Zirconium-doped chromium IV oxide) nanocomposite-based photocatalysts with different compositions (1, 3, 5, 7 & 9 wt.%) were prepared by an environmentally friendly, solid-state reaction at room temperature. The as-prepared samples were calcined under air at 450 °C in a furnace for a specific period of time. The synthesis of Zr/CrO2 photocatalysts was confirmed by various techniques, including XRD, SEM, EDX, FT-IR, UV-Vis, and BET. The photocatalytic properties of all samples were tested towards the degradation of methylene blue and methyl orange organic dyes under UV light. The results revealed a concentration-dependent photocatalytic activity of photocatalysts, which increased the amount of dopant (up to 5 wt.%). However, the degradation efficiency of the catalysts decreased upon further increasing the amount of dopant due to the recombination of holes and photoexcited electrons.
Highlights
Water pollution is one of the major environmental issues that arises from the discharge of organic dyes in wastewater, which is a threat to both aquatic and human life [1]
Various methods such as sol gel [23], coprecipitation [24], hydrothermal [25], sonication [26], ball mill [27], and flame pyrolysis [28] have been reported in the literature for the preparation of nanoparticle-based photocatalysts and their composites
The prepared Zr/CrO2 photocatalysts were characterized by their crystal structure, crystallite size, and phase composition by X-Ray diffraction technique
Summary
Water pollution is one of the major environmental issues that arises from the discharge of organic dyes in wastewater, which is a threat to both aquatic and human life [1]. Among the various metal oxides, CrO2 has attracted great scientific interest in the fields of materials science and physical chemistry, since it is the only half-metallic (HM) ferromagnetic (FM) material in 3d transition metal dioxide form [6] It offers various advantages, such as low cost [7], high thermal stability [8], and low toxicity [9]; it can potentially be applied for the degradation of methylene blue [10] and methyl orange dyes [11]. Various methods such as sol gel [23], coprecipitation [24], hydrothermal [25], sonication [26], ball mill [27], and flame pyrolysis [28] have been reported in the literature for the preparation of nanoparticle-based photocatalysts and their composites Such methods are often expensive, hazardous, and counterproductive to the fabrication of scalable and environmentally friendly composite materials. Photocatalytic experiments were carried out using the different samples under visible light
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