Fabrication of dual Z-scheme TiO2-WO3-CeO2 heterostructured nanocomposite with enhanced photocatalysis, antibacterial, and electrochemical performance

Fabrication of Dual Z-scheme TiO2-WO3-CeO2 heterostructured nanocomposite with enhanced photocatalysis, antibacterial, and electrochemical performance

Dye and nitro-compound pollution has become a significant issue worldwide. The adsorption and degradation of dyes and nitro-compounds have recently become important areas of study. Different methods, such as precipitation, flocculation, ultra-filtration, ion exchange, coagulation, and electro-catalytic degradation have been adopted for the adsorption and degradation of these organic pollutants. Apart from these methods, adsorption, photocatalytic degradation, and chemical degradation are considered the most economical and efficient to control water pollution from dyes and nitro-compounds. In this review, different kinds of dyes and nitro-compounds, and their adverse effects on aquatic organisms and human beings, were summarized in depth. This review article covers the comprehensive analysis of the adsorption of dyes over different materials (porous polymer, carbon-based materials, clay-based materials, layer double hydroxides, metal-organic frameworks, and biosorbents). The mechanism and kinetics of dye adsorption were the central parts of this study. The structures of all the materials mentioned above were discussed, along with their main functional groups responsible for dye adsorption. Removal and degradation methods, such as adsorption, photocatalytic degradation, and chemical degradation of dyes and nitro-compounds were also the main aim of this review article, as well as the materials used for such degradation. The mechanisms of photocatalytic and chemical degradation were also explained comprehensively. Different factors responsible for adsorption, photocatalytic degradation, and chemical degradation were also highlighted. Advantages and disadvantages, as well as economic cost, were also discussed briefly. This review will be beneficial for the reader as it covers all aspects of dye adsorption and the degradation of dyes and nitro-compounds. Future aspects and shortcomings were also part of this review article. There are several review articles on all these topics, but such a comprehensive study has not been performed so far in the literature.

https://www.mdpi.com/1420-3049/28/3/1081/pdf?version=1675431032

A Comprehensive Review on Adsorption, Photocatalytic and Chemical Degradation of Dyes and Nitro-Compounds over Different Kinds of Porous and Composite Materials

A new nanocomposite based on Cloisite 30B clay modified with ZnO and Ag2O nanoparticles (Cloisite 30B/ZnO/Ag2O) was synthesized as an effective catalyst in the sono-photocatalytic process of crystal violet (CV) and methylene blue (MB) dyes simultaneously. The characteristics and catalytic activity of Cloisite 30B/ZnO/Ag2O nanocomposite were investigated under different conditions. The specific active surface for Cloisite 30B/ZnO/Ag2O nanocomposite was 18.29 m2/g. Additionally, the catalytic activity showed that Cloisite 30B/ZnO/Ag2O nanocomposite (CV: 99.21%, MB: 98.43%) compared to Cloisite 30B/Ag2O (CV: 85.38%, MB: 83.62%) and Ag2O (CV: 68.21%, MB: 66.41%) has more catalytic activity. The catalytic activity of Cloisite 30B/ZnO/Ag2O using the sono-photocatalytic process had the maximum efficiency (CV: 99.21%, MB: 98.43%) at pH 8, time of 50 min, amount of 40 mM H2O2, catalyst dose of 0.5 g/L, and the concentration of ‘CV + MB’ of 5 mg/L. The catalyst can be reused in the sono-photocatalytic process for up to six steps. According to the results, •OH and h+ were effective in the degradation of the desired dyes using the desired method. Data followed the pseudo-first-order kinetic model. The method used in this research is an efficient and promising method to remove dyes from wastewater.

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Sono-Photocatalytic Activity of Cloisite 30B/ZnO/Ag2O Nanocomposite for the Simultaneous Degradation of Crystal Violet and Methylene Blue Dyes in Aqueous Media

The high-level contamination of pharmaceuticals in aquatic environment, and their toxicities is a serious issue. This review highlights the use of ceria photocatalyst for treatment of pharmaceuticals. Cerium oxide (CeO 2 ) with high oxygen storage, ecofriendly properties, reusability, and photostability contrary to other metal oxides photocatalysts is reportedly a better choice. However, ceria with high band gap energy show photoactivity mainly under UV light. This review highlights pharmaceuticals contamination in water, their contamination level, and toxicities and properties of CeO 2 and different approaches used for extending photoactivity of CeO 2 under visible irradiation. Metals and non-metals doping is found to promote greatly photoactivity of CeO 2 under visible irradiation by narrowing band gap, shift in absorption edge to visible region, crystal defects and yield of oxygen vacancy, lower recombination of conduction band electrons and valence band holes and increasing surface area. The visible irradiation of CeO 2 is found to produce hydroxyl radical ( OH) and superoxide radical (O 2 – ) which contribute in pharmaceuticals degradation. The electron paramagnetic resonance spectroscopy and radical scavenger studies confirmed the formation of reactive oxygen species from CeO 2 photoactivation. Doping was found to incorporate into the lattice of CeO 2 and improve reusability and stability of CeO 2 photocatalyst. The suggested mechanisms involved in the treatment of pharmaceuticals through OH and O 2 – is discussed. Furthermore, the outlook and future challenges in the use CeO 2 for photocatalytic degradation of pharmaceuticals and other organic pollutants are evaluated. • The sources and issues of different pharmaceuticals in water are discussed. • The design and importance of CeO 2 for degradation under visible light is discussed. • Key steps and processes in the modification and activation of CeO 2 are discussed. • Effects of different factors affecting performance of the photocatalyst is discussed. • Steps necessary for future perspective and potential use of CeO 2 are discussed. 

Visible light driven doped CeO2 for the treatment of pharmaceuticals in wastewater: A review

Sonophotocatalytic degradation of organic pollutant under visible light over Pt decorated CeO2: Role of ultrasonic waves for unprecedented degradation

Grass-derived carbon nanodots as a fluorescent-sensing platform for label-free detection of Cu (II) ions

Stabilization of Pt nanoparticles within MOFs for selective hydrogenation of hazardous 4-nitrophenol to valuable 4-aminophenol: Confinement and synergistic effect

Catalytic reduction is considered an effective approach for the reduction of toxic organic pollutants from the environment, but finding an active catalyst is still a big challenge. Herein, Ag decorated CeO2 catalyst was synthesized through polyol reduction method and applied for catalytic reduction (conversion) of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The Ag decorated CeO2 catalyst displayed an outstanding reduction activity with 99% conversion of 4-NP in 5 min with a 0.61 min−1 reaction rate (k). A number of structural characterization techniques were executed to investigate the influence of Ag on CeO2 and its effect on the catalytic conversion of 4-NP. The outstanding catalytic performances of the Ag-CeO2 catalyst can be assigned to strong synergistic interaction of Ag with CeO2 that prevents the aggregation of Ag species and also, helps in the exposure of more surface active metallic Ag0. In addition, the Ag-CeO2 catalyst shown remarkable durability up to several (five) repeated rounds, certifying its everyday applicability. 

Muhammad Farooq Khan

Papers

Sonophotocatalytic degradation of organic pollutant under visible light over Pt decorated CeO2: Role of ultrasonic waves for unprecedented degradation

Grass-derived carbon nanodots as a fluorescent-sensing platform for label-free detection of Cu (II) ions

Stabilization of Pt nanoparticles within MOFs for selective hydrogenation of hazardous 4-nitrophenol to valuable 4-aminophenol: Confinement and synergistic effect

An efficient Ag decorated CeO2 synergetic catalyst for improved catalytic reduction of lethal 4-nitrophenol

Elettaria cardamomum seed extract synthesized silver nanoparticles for efficient catalytic reduction of toxic dyes