An insight decipher on photocatalytic degradation of microplastics: Mechanism, limitations, and future outlook.

Plastic material manufacturing and buildup over the past 50 years has significantly increased pollution levels. Microplastics (MPs) and non-biodegradable residual plastic films have become the two most pressing environmental issues among the numerous types of plastic pollution. These tiny plastic flakes enter water systems from a variety of sources, contaminating the water. Since MPs can be consumed by people and aquatic species and eventually make their way into the food chain, their presence in the environment poses a serious concern. Traditional technologies can remove MPs to some extent, but their functional groups, stable covalent bonds, and hydrophobic nature make them difficult to eliminate completely. The urgent need to develop a sustainable solution to the worldwide contamination caused by MPs has led to the exploration of various techniques. Advanced oxidation processes (AOPs) such as photo-catalytic oxidation, photo-degradation, and electrochemical oxidation have been investigated. Among these, photocatalysis stands out as the most promising method for degrading MPs. Photocatalysis is an environmentally friendly process that utilizes light energy to facilitate a chemical reaction, breaking down MPs into carbon dioxide and water-soluble hydrocarbons under aqueous conditions. In photocatalysis, semiconductors act as photocatalysts by absorbing energy from a light source, becoming excited, and generating reactive oxygen species (ROS). These ROS, including hydroxyl radicals (•OH) and superoxide ions ( [Formula: see text] ), play a crucial role in the degradation of MPs. This extensive review provides a detailed exploration of the mechanisms and processes underlying the photocatalytic removal of MPs, emphasizing its potential as an efficient and environmentally friendly approach to address the issue of plastic pollution.

Doped graphitic carbon nitride (g-C3N4) catalysts for efficient photodegradation of tetracycline antibiotics in aquatic environments.

Tetracyclines (TCs) antibiotics are very common and often used in both human and veterinary medicines. More than 75% of TCs are excreted in an active condition and released into the environment, posing a risk to the ecosystem and human health. Residual antibiotics are in global water bodies, causing antibiotic resistance and genotoxicity in humans and aquatic organisms. The ever-increasing number of multi-resistant bacteria caused by the widespread use of antibiotics in the environment has sparked a renewed interest in developing more sustainable antibiotic degradation processes. In this regard, photodegradation technique provides a promising solution to resolve this growing issue, paving the way for complete antibiotic degradation with the generation of non-toxic by-products. As a fascinating activity towards visible light range shown by semiconductor, graphitic carbon nitride (g-C3N4) has a medium bandgap, non-toxicity, chemically stable complex, and thermally great strength. Recent studies have concentrated on the performance of g-C3N4 as a photocatalyst for treating wastewater. Pure g-C3N4 exhibits limited photocatalytic activity due to insufficient sunlight usage, small surface area, and a high rate of recombination of electron and hole ([Formula: see text] & [Formula: see text]) pairs created in photocatalytic activity. Doping of g-C3N4 is a very effective method for improving the activity as element doped g-C3N4 shows excellent bandgap and electronic structure. Doping significantly broadens the light-responsive range and reduces recombination of e- & h+ pairs. Under above context, this review provides a systematic and comprehensive outlook of designing doped g-C3N4 as well as efficiency for TCs degradation in aquatic environment.

Noble metal-free doped graphitic carbon nitride (g-C3N4) for efficient photodegradation of antibiotics: progress, limitations, and future directions.

Graphitic carbon nitride (g-C3N4) is well recognised as one of the most promising materials for photocatalytic activities such as environmental remediation via organic pollution elimination. New methods of nanoscale structure design introduce tunable electrical characteristics and broaden their use as visible light-induced photocatalysts. This paper summarises the most recent developments in the design of g-C3N4 with element doping. Various methods of introducing metal and nonmetal elements into g-C3N4 have been investigated in order to simultaneously tune the material's textural and electronic properties to improve its response to the entire visible light range, facilitate charge separation, and extend charge carrier lifetime. The degradation of antibiotics is one of the application domains of such doped g-C3N4. We expect that this research will provide fresh insights into clear design methods for efficient photocatalysts that will solve environmental challenges in a sustainable manner. Finally, the problems and potential associated with g-C3N4-based nanomaterials are discussed. This review is expected to encourage the ongoing development of g-C3N4-based materials for greater efficiency in photocatalytic antibiotic degradation.

Photocatalytic degradation of cyanide using polyurethane foam immobilized Fe-TCPP-S-TiO2-rGO nano-composite.

An attempt has been made for the treatment of cyanide contaminated wastewater using a S-TiO2@rGO heterogeneous photocatalyst system immobilized on polyurethane foam (PUF) supporting materials. Further, to make the photocatalytic system more efficient and active under visible light, a highly efficient iron porphyrin derivative sensitizer viz. Fe-TCPP was synthesized and employed for cyanide degradation. To investigate the synthesized heterogeneous nano-composite S-TiO2@rGO-FeTCPP photocatalytic system, advanced techniques such as XRD, XPS, FT-IR, PL spectra, UV-vis DRS, FESEM, and EDS were utilized. The photocatalytic performance of the nanocomposite was evaluated in a suspended system and results revealed that about 75% of cyanide degradation was obtained at 100 mg/L of initial cyanide within 2 h. Whereas, at the same condition, more than 91% of cyanide degradation as well as 88% toxicity removal occurred by the PUF immobilized S-TiO2@rGO-FeTCPP solid-state photocatalytic system. First-order kinetics was applied to investigate the degradation of cyanide by the photocatalytic nanocomposite. From the kinetic study, the estimated first-order rate constant (Kf) in a solid-state photocatalytic system of the nanocomposite was 1.7 times superior to that of the suspended system. Further, the rate of photocatalytic activity was nearly 10.8 times greater than that of pure TiO2. This study demonstrated that the immobilized S-TiO2@rGO-FeTCPP photocatalytic system could be an efficient technique for degrading cyanide from industrial effluent.