Ameliorative photocatalytic dye degradation of hydrothermally synthesized bimetallic Ag-Sn hybrid nanocomposite treated upon domestic wastewater under visible light irradiation

A novel photocatalytic degradation of mixed dye through chemically synthesized ZnO/Fe2O3 nanocomposite

This study reported the synthesis and assessment of zinc oxide/iron oxide (ZnO/Fe2O3) nanocomposite as photocatalysts for the degradation of a mixture of methylene red and methylene blue dyes. X-ray diffraction analysis confirms that the crystallite of zinc oxide (ZnO) has a hexagonal wurtzite phase and iron oxide (Fe2O3) has a rhombohedral phase. Fourier Transform Infra-Red spectrum confirms the presence of Zn-O vibration stretching at 428, 480 and 543 cm-1 stretching confirming Fe-O bond formation. Scanning Electron Microscope images exhibited a diverse size and shape of the nanocomposites. The ZnO-90%/Fe2O3-10% and ZnO-10%/Fe2O3-90% nanocomposites reveal good photocatalytic activity with reaction rate constants of 1.5 × 10-2 and 0.66 × 10-2; and 1.3 × 10-2 and 0.60 × 10-2 for methylene blue and methyl red dye respectively. The results revealed that the synthesized ZnO/Fe2O3 nanocomposite is the best catalyst for dye degradation and can be used for industrial applications in future.

In Situ Interfacial Engineering of CeO2/Bi2WO6 Heterojunction with Improved Photodegradation of Tetracycline and Organic Dyes: Mechanism Insight and Toxicity Assessment

The construction of heterojunction photocatalysts is an auspicious approach for enhancing the photocatalytic performance of wastewater treatment. Here, a novel CeO2/Bi2WO6 heterojunction is synthesized using an in situ liquid-phase method. The optimal 15% CeO2/Bi2WO6 (CBW-15) is found to have the highest photocatalytic activity, achieving a degradation efficiency of 99.21% for tetracycline (TC), 98.43% for Rhodamine B (RhB), and 94.03% for methylene blue (MB). The TC removal rate remained at 95.38% even after five cycles. Through active species capture experiments, •O2 -, h+, and •OH are the main active substances for TC, RhB, and MB, respectively. The possible degradation pathways for TC are analyzed using liquid chromatography-mass spectrometry (LC-MS). The photoinduced charge transfer and possible degradation mechanisms are proposed through experimentation and density functional theory (DFT) calculations. Toxicity assessment experiments show a significant reduction in toxicity during the TC degradation process. This study uncovers the mechanism of photocatalytic degradation in CeO2/Bi2WO6 and provides new insights into toxicity assessment.

Biodegradation of commercial textile reactive dye mixtures by industrial effluent adapted bacterial consortium VITPBC6: a potential technique for treating textile effluents

Textile industries release major fraction of dyestuffs in effluents leading to a major environmental concern. These effluents often contain more than one dyestuff, which complicates dye degradation. In this study ten reactive dyes (Reactive Yellow 145, Reactive Yellow 160, Reactive Orange 16, Reactive Orange 107, Reactive Red 195, Reactive Blue 21, Reactive Blue 198, Reactive Blue 221, Reactive Blue 250, and Reactive Black 5) that are used in textile industries were subjected to biodegradation by a bacterial consortium VITPBC6, formulated in our previous study. Consortium VITPBC6 caused single dye degradation of all the mentioned dyes except for Reactive Yellow 160. Further, VITPBC6 efficiently degraded a five-dye mixture (Reactive Red 195, Reactive Orange 16, Reactive Black 5, Reactive Blue 221, and Reactive Blue 250). Kinetic studies revealed that the five-dye mixture was decolorized by VITPBC6 following zero order reaction kinetic; Vmax and Km values of the enzyme catalyzed five-dye decolorization were 128.88 mg L-1 day-1 and 1003.226 mg L-1 respectively. VITPBC6 degraded the dye mixture into delta-3,4,5,6-Tetrachlorocyclohexene, sulfuric acid, 1,2-dichloroethane, and hydroxyphenoxyethylaminohydroxypropanol. Phytotoxicity, cytogenotoxicity, microtoxicity, and biotoxicity assays conducted with the biodegraded metabolites revealed that VITPBC6 lowered the toxicity of five-dye mixture significantly after biodegradation.

Sn-based materials in photocatalysis: A review

Development and the application of Sn-based materials have become more prevalent in recent years due to concerns regarding the energy crisis, environmental pollution, and the urgent need of constructing inexpensive and highly effective photocatalysis. The recent advancement in Sn-based materials for efficient photocatalysts, such as Sn alloys, Sn oxides, Sn sulfides, Sn selenides, Sn niobates, Sn tantalites, and Sn tungstates, is summarized in this study. Several design ideas for increasing the photoactivity of Sn-based materials in various photocatalytic applications are emphasized. In addition, we considered their present applications in energy generation (H2 evolution, CO2 reduction, and N2 fixation) and environmental remediation (air purification and wastewater treatment). As a result, the current review will deepen the reader's understanding of the properties and potential uses of Sn-based materials in photocatalysis. Hence, this paper will serve as a guide in promoting the domain of Sn-based materials for future photocatalytic technologies.

Sustainable fabrication of hybrid silver-copper nanocomposites (Ag-CuO NCs) using Ocimum americanum L. as an effective regime against antibacterial, anticancer, photocatalytic dye degradation and microalgae toxicity

In this study, a sustainable fabrication of hybrid silver-copper oxide nanocomposites (Ag-CuO NCs) was accomplished utilizing Ocimum americanum L. by one pot green chemistry method. The multifarious biological and environmental applications of the green fabricated Ag-CuO NCs were evaluated through their antibacterial, anticancer, dye degradation, and microalgae growth inhibition activities. The morphological features of the surface functionalized hybrid Ag-CuO NCs were confirmed by FE-SEM and HR-TEM techniques. The surface plasmon resonance λ_max peak appeared at 441.56 nm. The average hydrodynamic size distribution of synthesized nanocomposite was 69.80 nm. Zeta potential analysis of Ag-CuO NCs confirmed its remarkable stability at -21.5 mV. XRD and XPS techniques validated the crystalline structure and electron binding affinity of NCs, respectively. The Ag-CuO NCs demonstrated excellent inhibitory activity against Vibrio cholerae (19.93 ± 0.29 mm) at 100 μg/mL. Anticancer efficacy of Ag-CuO NCs was investigated against the A549 lung cancer cell line, and Ag-CuO NCs exhibited outstanding antiproliferative activity with a low IC₅₀ of 2.8 ± 0.05 μg/mL. Furthermore, staining and comet assays substantiated that the Ag-CuO NCs hindered the progression of the A549 cells and induced apoptosis as a result of cell cycle arrest at the G₀/G₁ phase. Concerning the environmental applications, the Ag-CuO NCs displayed efficient photocatalytic activity against eosin yellow degradation up to 80.94% under sunlight irradiation. Microalgae can be used as an early bio-indicator/prediction of environmental contaminants and toxic substances. The treatment of the Ag-CuO NCs on the growth of marine microalgae Tetraselmis suecica demonstrated the dose and time-dependent growth reduction and variations in the chlorophyll content. Therefore, the efficient multifunctional properties of hybrid Ag-CuO NCs could be exploited as a regime against infective diseases and cancer. Further, the findings of our investigation witness the remarkable scope and potency of Ag-CuO NCs for environmental applications.

Room-Temperature Synthesis of Carbon Dot/TiO2 Composites with High Photocatalytic Activity

Benefiting from the wide-range absorption and adjustable energy gap, carbon dots (C-dots) have attracted a great deal of attention and they have been used to sensitize semiconductor nanocomposites to boost the efficiency of energy conversion devices, while there is still a lack of fundamental understanding of the interaction between such materials and their influence on the catalytic activity on the reaction process. In this study, C-dots were used to modify TiO₂ to form a direct Z-scheme (DZS) junction for enhancement of the photocatalytic activity. The C-dot/TiO₂ composite was prepared by ultrasonication at room temperature through coupling between the Ti-O-C bond and electrostatic interaction. The C-dots can dramatically enhance the absorption of the composite by forming the DZS, and the composite is enabled to generate more free radicals, which facilitate ∼10 times higher photocatalytic activity compared to that of TiO₂. As a proof of concept, the as-prepared C-dot/TiO₂ was used for textile wastewater dye degradation. This study provides an efficient approach for room-temperature preparation of C-dot/TiO₂ composites with high photocatalytic activity.

Preparation of MnO2-Carbon Materials and Their Applications in Photocatalytic Water Treatment

Water pollution is one of the most important problems in the field of environmental protection in the whole world, and organic pollution is a critical one for wastewater pollution problems. How to solve the problem effectively has triggered a common concern in the area of environmental protection nowadays. Around this problem, scientists have carried out a lot of research; due to the advantages of high efficiency, a lack of secondary pollution, and low cost, photocatalytic technology has attracted more and more attention. In the past, MnO₂ was seldom used in the field of water pollution treatment due to its easy agglomeration and low catalytic activity at low temperatures. With the development of carbon materials, it was found that the composite of carbon materials and MnO₂ could overcome the above defects, and the composite had good photocatalytic performance, and the research on the photocatalytic performance of MnO₂-carbon materials has gradually become a research hotspot in recent years. This review covers recent progress on MnO₂-carbon materials for photocatalytic water treatment. We focus on the preparation methods of MnO₂ and different kinds of carbon material composites and the application of composite materials in the removal of phenolic compounds, antibiotics, organic dyes, and heavy metal ions in water. Finally, we present our perspective on the challenges and future research directions of MnO₂-carbon materials in the field of environmental applications.

Photocatalytic and Antimicrobial Activities of Biosynthesized Silver Nanoparticles Using Cytobacillus firmus

The toxicity of the ecosystem has increased recently as a result of the increased industrial wastewater loaded with organic contaminants, including methylene blue (MB), which exerts serious damage to the environment. Thus, the present work aims to green the synthesis of silver nanoparticles (Ag-NPs) and to evaluate their degradability of notorious MB dye, as well as their antimicrobial activities. Ag-NPs were synthesized by Cytobacillus firmus extract fully characterized by UV-vis, TEM, DLS, XRD, and FTIR. Ag-NPs showed good antibacterial and antifungal activities against Escherichia coli ATCC 25922, Enterococcus feacalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, and Candida albicans ATCC 90028. Moreover, Ag-NPs exhibited a high biodegradability level (98%) of MB dye after 8 h of co-incubation in the presence of sunlight. Additionally, the phytotoxicity of treated MB dye-contaminated water sample showed good germination of Vicia faba as compared with non-treated MB dye-contaminated solution. In conclusion, the herein biosynthesized Ag-NPs demonstrated its feasibility of the purification of contaminated water from microbes and methylene blue dye and the probability of reusing purified water for agricultural purposes.

Visible-NIR light-responsive 0D/2D CQDs/Sb2WO6 nanosheets with enhanced photocatalytic degradation performance of RhB: Unveiling the dual roles of CQDs and mechanism study

Environmental pollution caused by dye wastewater discharge has attracted much attention in the past decades. Developing photocatalysts with high solar energy utilization efficiency for the treatment of dye wastewater is one of the most promising methods to address afore-mentioned environmental problem. Herein, novel Vis-NIR (visible to near-infrared) light-responsive carbon quantum dots modified Sb₂WO₆ (CQDs/Sb₂WO₆) nanosheets with remarkably enhanced photocatalytic degradation performance of Rhodamine B (RhB) aqueous solution were successfully synthesized. Under the irradiation of Vis light, the photocatalytic degradation efficiency reaches 83% over the optimal composite, which is nearly seven times higher than that of pristine Sb₂WO₆. Meanwhile, under NIR light irradiation, the optimal composite also keeps a stable degradation performance, while pristine Sb₂WO₆ exhibits sluggish performance. Besides, a detailed photocatalytic degradation pathway was proposed via the analyses of corresponding intermediates in the photocatalytic degradation process. On the basis of electron spin resonance spectrometry, quenching experiment and density functional theory (DFT) calculation, hydroxyl radicals (•OH) play a dominating role in the photocatalytic reactions and a possible photocatalytic degradation mechanism was unearthed. This work provides new insights for constructing novel Vis-NIR responsive photocatalysts to purify dye wastewater for environmental remediation.

A well-defined S-g-C3N4/Cu–NiS heterojunction interface towards enhanced spatial charge separation with excellent photocatalytic ability: synergetic effect, kinetics, antibacterial activity, and mechanism insights

A well-defined heterojunction among two dissimilar semiconductors exhibited enhanced photocatalytic performance owing to its capability for boosting the photoinduced electron/hole pair transportation. Therefore, designing and developing such heterojunctions using diverse semiconductor-based materials to enhance the photocatalytic ability employing various approaches have gained research attention. For this objective, g-C₃N₄ is considered as a potential photocatalytic material for organic dye degradation; however, the rapid recombination rate of photoinduced charge carriers restricts the widespread applications of g-C₃N₄. Henceforth, in the current study, we constructed a heterojunction of S-g-C₃N₄/Cu–NiS (SCN/CNS) two-dimensional/one-dimensional (2D/1D) binary nanocomposites (NCs) by a self-assembly approach. XRD results confirm the construction of 22% SCN/7CNS binary NCs. TEM analysis demonstrates that binary NCs comprise Cu–NiS nanorods (NRs) integrated with nanosheets (NSs) such as the morphology of SCN. The observed bandgap value of SCN is 2.69 eV; nevertheless, the SCN/CNS binary NCs shift the bandgap to 2.63 eV. Photoluminescence spectral analysis displays that the electron–hole pair recombination rate in the SCN/CNS binary NCs is excellently reduced owing to the construction of the well-defined heterojunction. The photoelectrochemical observations illustrate that SCN/CNS binary NCs improve the photocurrent to ∼0.66 mA and efficiently suppress the electron–hole pairs when compared with that of undoped NiS, CNS and SCN. Therefore, the 22% SCN/7CNS binary NCs efficiently improved methylene blue (MB) degradation to 99% for 32 min under visible light irradiation.

A well-refined heterointerface combination of a 2D/1D SCN/CNS binary heterojunction is developed.

Optimization of photocatalytic degradation conditions and toxicity assessment of norfloxacin under visible light by new lamellar structure magnetic ZnO/g-C3N4

Degradation of norfloxacin (NFX) by zinc oxide (ZnO)/g-C₃N₄, a magnetic sheet ZnO with g-C₃N₄ on its surface was studied. Through a new preparation system method, hydrothermal reaction provides a solid-layered magnetic ZnO material basis, and the simple thermal condensation method was used to transform the urea into g-C₃N₄ on the magnetic sheet ZnO in a uniform and orderly manner to increase the stability and photocatalytic performance of the material. Compared with previous studies, the pore volume and photocatalytic performance of the material are improved, and became more stable. By studying the degradation effect of basic and photocatalytic materials prepared in different proportions, the kinetic constant of ZGF is 0.01446 (min^-1). The response surface methodology (RSM) was used to study the optimization and effect of solution pH (4-12), photocatalyst concentration (0.2-1.8 g/L), and NFX concentration (3-15 mg/L) on the degradation rate of NFX during photocatalytic degradation. The R² value of the RSM model was 0.9656. The NFX removal rate is higher than 90% when the amount of catalyst is 1.43 g/L, the solution pH is 7.12, and the NFX concentration is less than 8.61 mg/L. After 5 cycles, the degradation rate of magnetic materials decreased to 92.8% of the first time. The capture experiment showed that the photocatalytic machine Toxicities was mainly hole action. The TOC removal rate within 2 h was 30%, a special intermediate toxicity analysis method was adopted according to the characteristics of NFX's inhibitory effect on Escherichia coli community. The toxicity of degraded NFX solution disappeared, and the possibility of non-toxic harm of by-products was verified. LC-Q-TOF method was used to detect and analyze various intermediate products converted from NFX after photocatalytic degradation, and the photocatalytic degradation pathway of NFX was proposed.