Current perspective in metal oxide based photocatalysts for virus disinfection: A review

Preparation of polyethyleneimine modified cellulose/nano-CdS composite aerogel and its photocatalytic properties for organic dyes under visible light

Organic dyes are extensively used in industries such as textiles and printing, contributing to the increasing discharge of wastewater and posing significant risks to human health. Conventional photocatalysts, including metal oxides and sulfides, often exhibit limited pollutant adsorption capacities and suffer from charge carrier recombination. In this study, we synthesized a novel composite aerogel via the lyophilization of cellulose modified with polyethyleneimine and cadmium sulfide. This composite demonstrated exceptional efficacy in degrading of methyl orange (MO) and methylene blue (MB). The composite exhibits a unique three-dimensional structure characterized by a multitude of uneven pores, providing abundant active sites favorable for catalytic reactions. Furthermore, the material shows significant light absorption within the visible spectrum and has a low band gap. Under optimized conditions, the removal efficiencies of MO and MB reached 99.56 % and 100 %, respectively. After five consecutive cycles, the degradation rates of MO and MB remained high at 83 % and 87 %, respectively, showcasing excellent photocatalytic activity and stability. The amino and hydroxyl groups within the composite act as electron donors during photocatalytic reactions, with reaction kinetics following a quasi-first-order model. The mechanism of dye removal by the composite involves a synergistic interplay between adsorption and photocatalytic reduction, underscoring its potential for efficient wastewater treatment.

Deciphering the virucidal potential of hydroxyl radical during ozonation: Implications for waterborne virus inactivation

The heightened public health risks associated with viral contamination in water have led to a strong emphasis on effective disinfection strategies. Ozone is a potent disinfectant widely employed for the inactivation of pathogens, yet comprehensive reports detailing the virucidal efficacy of hydroxyl radical (•OH) generated during ozonation are limited. The present research meticulously deciphered the role and influencing factors of •OH during ozone disinfection processes, elucidating how •OH enhanced ozone-mediated virus inactivation from both kinetic and molecular biological perspectives. The inactivation rate constants of ozone-derived •OH for Phi6 (9.67 × 1010 M-1 s-1) and PhiX174 (3.85 × 1010 M-1 s-1) were 4-5 orders of magnitude higher than those of ozone molecules. At 20 °C and pH 7.0, the contribution of •OH to the reduction of viral infectivity has been quantified as ranging from 11.3 % to 52.7 %. The yield of •OH increased notably as pH rose from 6.0 to 8.0, which was the principal cause for the accelerated apparent virus inactivation rates by ozone. An elevation in temperature (10-30 °C) had a negligible impact on •OH yield but facilitated virus removal by enhancing the reactivity of oxidants with viral particles. The damage inflicted on the viral genome by •OH vastly surpassed that caused by ozone, with the log reduction in gene copies in the presence of •OH being 297-343 % higher than the effect observed with ozone alone. The potential interaction sites of ozone and •OH with viral genetic material were predicted using Density Functional Theory static calculations and further compared. The present research offers comprehensive insights into the inactivation capabilities and underlying mechanisms of •OH for the effective control of waterborne viruses, establishing a theoretical foundation for employing the advanced oxidation properties of ozone-derived •OH in developing innovative water disinfection strategies.

A review on conducting organic polymers: Concepts, applications, and potential environmental benefits

Polymer materials have long been valued for their insulating properties. But recent advancements have revealed their potential as electrically conductive materials, offering an alternative to traditional metallic conductors with the added benefit of reduced environmental impact. This review article provides a comprehensive overview of conducting organic polymers, focusing on their conceptual foundations, diverse applications, and their significant role in mitigating environmental pollution. The paper begins with an exploration of how polymeric materials have progressed from insulators to conductors, explaining the basic principles and mechanisms behind their electrical conductivity. It then provides an insight into the various applications enabled by their unique optical and electronic properties, including their use in light-emitting diodes, electrochromic displays, smart windows, fuel cells, solar cells, supercapacitors and batteries. Additionally, the review emphasizes the potential of conducting organic polymers in mitigating environmental pollution, particularly through their role in wastewater treatment and e-waste management. By examining recent advancements and promising future prospects, this article underscores the potential of conducting organic polymers to revolutionize both electronic technology and environmental sustainability.

Porphyrin-Based Metal-Organic Framework Photocatalysts: Structure, Mechanism and Applications

In recent years, porphyrins have been frequently reported as photocatalysts due to their fascinating photochemical properties. However, porphyrins have the same shortcomings as other homogeneous photocatalysts, such as poor stability and difficulty in recovering. To solve this problem, it is a good strategy to form a porphyrin-based metal-organic framework (PMOF) by modifying porphyrin functional groups and adding metals as nodes to connect and control the arrangement of porphyrins. The metal nodes control the rigidity and connectivity of the porphyrin modules to order them in the MOF, which improves the stability of the porphyrins, avoids porphyrin aggregation and folding, and increases the active sites for photocatalytic reactions. This review summarized the research progress of PMOF photocatalysts in the last ten years and analyzed the effects of the spatial structure, porphyrin ligands, porphyrin central metals, and metal nodes of PMOF on the photocatalytic performance. The applications of PMOF-based photocatalysts in H2 production, CO2 reduction, pollutant degradation, and sterilization are reviewed. In addition, the mechanism of these processes is described in detail. Finally, some suggestions on the development of PMOF photocatalysts are put forward.

Boosted electrocatalytic activity and durability of CuFe/NC by modulating the interfacial composition and electronic structure for efficient oxygen reduction reaction

Oxygen reduction reaction (ORR) serves as the foundation for various electrochemical energy storage devices. Fe/NC catalysts are expected to replace commercial Pt/C as oxygen electrode catalysts based on the structural tunability at the atomic level, abundant iron ore reserves and excellent activity. Nevertheless, the lack of durability and low active site density impede its advancement. In this work, a durable catalyst, CuFe/NC, for ORR was prepared by modulating the interfacial composition and electronic structure. The introduction of Cu nanoclusters partially eliminates the Fenton effect from Fe and optimizes the electron structure of FeNx, thereby effectively enhancing the long-term durability and activity. The prepared CuFe/NC exhibits a half-wave potential (E1/2) of 0.90 V and superior stability with a decrease in E1/2 of only 20 mV after 10,000 cycles. The assembled alkaline Zinc-Air batteries (ZABs) with CuFe/NC exhibit an open-circuit potential of 1.458 V. At a current density of 5 mA cm-2, the batteries are capable of operation for 600 h with a stable polarization. This CuFe/NC may promote the practical application of novel and renewable electrochemical energy storage devices.

Dual-synergistic effect of medium-entropy metal sulfoselenide nanoparticles toward efficient overall seawater splitting

Developing efficient and durable electrodes for overall water splitting (OWS) in seawater electrolytes is a major challenge. Herein, we synthesized highly active and stable Fe1.2(CoNi)1.8S3Se3 medium-entropy metal sulfoselenide (MESSe) nanoparticles for the electrodes. The Fe1.2(CoNi)1.8S3Se3 MESSe electrode exhibited excellent electrocatalytic performance in alkaline simulated seawater, with a η100 value of 156 mV for the hydrogen evolution reaction and 262 mV for the oxygen evolution reaction. Compared to Fe1.2(CoNi)1.8S6 sulfide and Fe1.2(CoNi)1.8Se6 selenide, the electronic structure of Fe1.2(CoNi)1.8S3Se3 MESSe positively modulates the adsorption/desorption process of *H/*OH intermediate and significantly reduces the free energy of the rate-determining step, thereby accelerating the reaction kinetics of both hydrogen/oxygen evolution reactions. The performance of OWS is significantly enhanced by utilizing the prepared electrode, enabling it to achieve 100 mA cm-2 with only 1.77 V in alkaline simulated seawater. Furthermore, the durability of the electrode is maintained at this high current density in alkaline simulated seawater, alkaline seawater as well as seawater electrolyte. This work will lay the foundation for the development of innovative medium-entropy metal sulfoselenides, promoting their application in a wide range of electrochemical energy systems operating under extreme conditions.

Rational Design of Mesoporous ZnFe2O4@g-C3N4 Heterojunctions for Environmental Remediation and Hydrogen Evolution

Mesoporous catalysts with a high specific surface area, accessible pore structures, and appropriate band edges are desirable for optimal charge transfer across the interfaces, suppress electron-hole recombination, and promote redox reactions at the active sites. The present study demonstrates the rational design of mesoporous ZnFe2O4@g-C3N4 magnetic nanocomposites (MNCs) with different pore sizes and pore volumes following a combination of facile thermal itching and thermal impregnation methods. The MNCs preserve the structural, morphological, and physical attributes of their counterparts while ensuring their effectiveness and superior catalytic capabilities. The morphological analysis confirms the successful grafting and confinement of ZnFe2O4 nanoparticles with the polymeric g-C3N4 nanosheets to form heterojunctions with numerous interfaces. The MNCs possess uniformly distributed small mesopores (pore size <4 nm), ample active sites, and a high specific surface area of 62.50 m2/g. The mesoporous ZnFe2O4@g-C3N4 notably improve hydrogen evolution rate and methylene blue dye degradation. The optimal loading weight of ZnFe2O4 is 20 %, in which the MNCs display the highest hydrogen evolution rate of 1752 μmol g-1 h-1 and photo-Fenton dye degradation rate constants of 0.147 min-1, upon solar-light illumination. Furthermore, the photocatalysts demonstrate recyclability over five consecutive cycles, confirming their stability, while easy separation using a simple magnet underscores practical utility.

Photocatalytic degradation of antibiotics by N-doped carbon nanoflakes-nickel ferrite composite derived from algal biomass

This work reports the synthesis of nickel ferrite (NiFe) nanoparticles, N-doped mesoporous carbon nanoflakes (NCF) and novel nickel ferrite-carbon nanoflakes (NiFe@NCF) nanocomposite using solvothermal method. NCF was derived from a cyanobacterial consortium consisting of Anabaena, Lyngbya and Weistiellopsis, rich in carbon and nitrogen. The synthesized nanoparticles were used as heterogeneous photocatalyst for degradation of two harmful water pollutants, ciprofloxacin (CIP) and levofloxacin (LEV). 99.91% LEV and 98.86% CIP were degraded within 50 and 70 min of visible light irradiation using NiFe@NCF following pseudo first order kinetics. This improved efficiency of the nanocomposite may be attributed to its higher surface area, reduction of band gap (from 2.42 to 2.19 eV), more active sites as well as charge carrier mobility with decreasing agglomeration tendency of the magnetic nickel nanoparticles upon being embedded on NCF. N-doping improves light harvesting property, retards charge recombination and extends as well as delocalises ᴨ-conjugated system resulting in enhanced photocatalytic activity. The scavenging experiments and EPR analysis reveal that O2-• and •OH are the main active species taking part in the degradation process. The material performs well within a wide range of pH and can be effectively used up to 5 repetitive cycles. A feasible photocatalytic degradation mechanism of the antibiotics against NiFe@NCF nanocomposite is also put forwarded along with their possible degradation pathways from LCMS studies.

Ultra-fast photocatalytic degradation of Rhodamine B exploiting oleate-stabilized zinc oxide nanoparticles

Rhodamine B (RhB) is a harmful dye released by industrial wastewaters, thus necessitating its urgent removal. Advanced oxidation processes constitute promising strategies to purify polluted water. Among others, photocatalysis relies on reactive oxygen species (ROS) produced by photocatalytic particles, typically semiconductors like titania or zinc oxide (ZnO), excited by solar or UV-Vis light. However, their wide band gap limits their catalytic capabilities within the absorption of the UV spectrum and causes fast electron-hole recombination. This study presents novel strategies to overcome these limitations: (i) doping semiconductors to increase photocatalytic efficiency; (ii) sensitization-mediated photocatalysis for visible light activation using chemical moieties to trap dye molecules; (iii) nanosizing the photocatalysts to enhance the surface area. ZnO nanoparticles, doped with iron or gadolinium and capped with oleic acid are here synthesized and tested in RhB dye solutions. Remarkably, the results demonstrate an ultra-fast RhB degradation, driven by oleic acid having crucial role in dye adsorption. The degradation mechanisms, including ROS-induced N-deethylation and xanthene group cleavage, are also unraveled. These findings underscore the efficacy of the proposed semiconductor photocatalyst design, highlighting a significant advancement with extensive potential applications in wastewater remediation. This innovative approach paves the way for more efficient and practical solutions to combat industrial dye pollution.

Unlocking enhanced photocatalytic power: Donor-acceptor synergy in non-metallic g-C3N4 hollow nanospheres

Selecting safe, non-toxic, and non-metallic semiconductor materials that facilitate the degradation of pollutants in water stands out as an optimal approach to combat environmental pollution. Herein, graphitic carbon nitride (g-C3N4)-based hollow nanospheres nonmetallic photocatalyst modified with covalent organic framework materials named TpMA, based on 1, 3, 5-trimethylchloroglucuronide (Tp) and melamine (MA), was successfully synthesized (abbreviated as CNTP). The ordered electron donor-acceptor structure inherent in TpMA contributed to enhancing the transport efficiency of photogenerated carriers in CNTP. The CNTP photocatalysts exhibited excellent performance in degrading rhodamine B and tetracycline in visible light, with optimal degradation rates reached more than 90% in 60 and 80 min, respectively, which were 5.3 and 3.0 times higher than those of pure CNNS. The increased photocatalytic efficiency observed in CNTP composites could be traced back to the covalently connection between the two molecules, forming a π-conjugated system that facilitated the separative efficiency of photogenerated electron-hole pairs and intensified the utilization of visible light. This study provided a new means to design and fabricate highly efficient and environmentally friendly non-metallic photocatalytic materials.

Advanced photocatalytic disinfection mechanisms and their challenges

Currently, microbial contamination issues have globally brought out a huge health threat to human beings and animals. To be specific, microorganisms including bacteria and viruses display durable ecological toxicity and various diseases to aquatic organisms. In the past decade, the photocatalytic microorganism inactivation technique has attracted more and more concern owing to its green, low-cost, and sustainable process. A variety kinds of photocatalysts have been employed for killing microorganisms in the natural environment. However, two predominant shortcomings including low activity of photocatalysts and diverse impacts of water characteristics are still displayed in the current photocatalytic disinfection system. So far, various strategies to improve the inherent activity of photocatalysts. Other than the modification of photocatalysts, the optimization of environments of water bodies has been also conducted to enhance microorganisms inactivation. In this mini-review, we outlined the recent progress in photocatalytic sterilization of microorganisms. Meanwhile, the relevant methods of photocatalyst modification and the influences of water body characteristics on disinfection ability were thoroughly elaborated. More importantly, the relationships between strategies for constructing advanced photocatalytic microorganism inactivation systems and improved performance were correlated. Finally, the perspectives on the prospects and challenges of photocatalytic disinfection were presented. We sincerely hope that this critical mini-review can inspire some new concepts and ideas in designing advanced photocatalytic disinfection systems.

Enhancing photodegradation of thiamethoxam insecticide using SnS2/NCL as a photocatalyst: Mechanistic insights and environmental implications

The current research highlights the fabrication of a novel SnS2/CO32-@Ni-Co LDH (SnS2/NCL) by precipitating Ni-Co LDH over hydrothermally synthesized SnS2 nanoparticles for the enhanced degradation of thiamethoxam (THM) insecticide through the advanced oxidation process. The effect of several reaction parameters was optimized, and a maximum degradation of 98.1 ± 1.2 % with a rate constant of 0.0541 min-1 of 10 ppm THM was reached at a catalyst loading of 0.16 gL-1 using 0.3 mM of H2O2 within 70 min of visible light irradiation. The effect of metal cations, inorganic anions, dissolved organic matter, organic compounds and water samples on the photodegradation performance of SnS2/NCL nanocomposite was also examined to evaluate the prepared photocatalyst's suitability for use in actual wastewater conditions. The metal cations blocked the active sites of the photocatalyst and reduced the degradation efficiency except for Fe2+ ions, since it is a Fenton reagent and increased the production of hydroxyl radicals. Inorganic anions are the scavengers of hydroxyl radicals and hinder photocatalytic activity. Meanwhile, lake water containing varying degrees of co-existing ions shows the lowest degradation efficiency among other water samples. The SnS2/NCL nanocomposite could be reused for five cycles while maintaining a photocatalytic efficiency of 83.6 ± 0.3 % in the fifth run. The prepared SnS2/NCL nanocomposite also showed excellent photodegradation of several other emerging organic pollutants with an efficiency of over 80 % under optimum conditions. Incorporating Ni-Co LDH with SnS2 helped to delocalize photoinduced charges, leading to increased photocatalytic activity and a slower electron-hole recombination rate. The present research highlights the photocatalytic activity of SnS2/NCL photocatalysts for the photocatalytic degradation of emerging contaminants from wastewater.

The coupled WO3-AgBr nanocatalyst, part II: Synthesis, characterization, and the boosted photocatalytic activity towards metronidazole in an aqueous solution

The AgBr and WO3 nanoparticles (NPs) were synthesized and coupled, and the coupled AgBr-WO3 binary catalyst, as well as the individual AgBr and WO3 NPs, were then characterized by XRD, FTIR, DRS, and SEM-EDX. XRD results showed the formation of orthorhombic WO3 cubic AgBr crystals. The crystallite sizes of 45, 28, and 45 nm were estimated by the Scherrer formula for the as-prepared AgBr, WO3, and AgBr-WO3 catalysts, respectively. The DRS study estimated band gap energies using both absorption edge wavelengths and the Kubelka-Munk model. The band gap energies of 2.72, 3.06, and 2.92 eV were obtained for the direct electronic transitions of AgBr, WO3, and AgBr-WO3. The ECB (potential position) of AgBr and WO3 were estimated to be 0.01 and 0.52 V, while their EVB values were 2.60 and 3.55 V, respectively. Typical FTIR absorption bands of W‒OH, the W‒O‒W, and AgBr bonds have appeared at 1637 cm-1, 823 (and 766) cm-1, and 1384 cm-1, respectively. The pHpzc of 4 was estimated for the individual and coupled catalysts. In studying the photocatalytic activity of the catalysts in the photodegradation of metronidazole (MNZ) a boosted activity was achieved for the coupled system. This increased activity depends on the maximum AgBr:WO3 mole ratio in a 1:3 mol ratio. Grinding time applied to prepare the coupled catalyst has also varied the photocatalytic activity.

Versatile Antibacterial and Antioxidant Bacterial Cellulose@Nanoceria Biotextile: Application in Reusable Antimicrobial Face Masks

Despite considerable interest in medical and pharmaceutical fields, there remains a notable absence of functional textiles that concurrently exhibit antibacterial and antioxidant properties. Herein, a new composite fabric constructed using nanostructured bacterial cellulose (BC) covalently-linked with cerium oxide nanoparticles (BC@CeO2NPs) is introduced. The synthesis of CeO2NPs on the BC is performed via a microwave-assisted, in situ chemical deposition technique, resulting in the formation of mixed valence Ce3+/Ce4+ CeO2NPs. This approach ensures the durability of the composite fabric subjected to multiple washing cycles. The Reactive oxygen species (ROS) scavenging activity of CeO2NPs and their rapid and efficient eradication of >99% model microbes, such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus remain unaltered in the composite. To demonstrate the feasibility of incorporating the fabric in marketable products, antimicrobial face masks are fabricated with filter layers made of BC@CeO2NPs cross-linked with propylene or cotton fibers. These masks exhibit complete inhibition of bacterial growth in the three bacterial strains, improved breathability compared to respirator masks and enhanced filtration efficiency compared to single-use surgical face masks. This study provides valuable insights into the development of functional BC@CeO2NPs biotextiles in which design can be extended to the fabrication of medical dressings and cosmetic products with combined antibiotic, antioxidant and anti-inflammatory activities.

Enhanced photocatalytic activity of V3O7 / V2O5 - reduced graphene oxide nanocomposite towards methylene blue dye degradation

This work investigates the photocatalytic performance of V2O5 and V3O7 nanoparticles and their nanocomposites with rGO. The as-annealed V2O5 and V3O7 nanoparticles exhibited pure orthorhombic and monoclinic structures with an optical bandgap of 2.3 and 2.5 eV, respectively. The corresponding vibrational modes using Raman and FTIR spectroscopy analysis further confirm the form. The morphological studies reveal that V2O5 and V3O7 nanoparticles possess plate and petal-like morphology, respectively. Moreover, in the case of V2O5/V3O7-rGO nanocomposites, the plate/petal-like nanoparticles are embedded within rGO sheets. Incorporating nanoparticles within rGO sheets has quenched the green photoluminescence emission, enhancing their photocatalytic performance upon irradiation with white light of 100 mW/cm2. This is ascribed to the effective transport of interfacial electrons from vanadium oxide nanoparticles to the rGO surface, reducing the recombination of photogenerated charge carriers. These results indicate that the vanadium oxide/rGO nanocomposites have potential applications in wastewater treatment.

Rational design of full-spectrum visible-light-responsive bimetallic sulfide Bi2S3/CoS2 composites for high-efficiency photocatalytic degradation of naproxen and bacterial inactivation

Photocatalytic water decontamination has emerged as a highly promising technology for efficient and rapid water treatment, harnessing sustainable solar energy as its driving force. In this study, we prepared visible-light active Bi2S3/CoS2 composites for the degradation of naproxen (NPX) and the inactivation of Escherichia coli (E. coli). The homogeneous dispersion of CoS2 was stably integrated with Bi2S3, resulting in a significant enhancement of the specific surface area, efficient utilization of visible light, and effective separation of photogenerated charge carriers. Consequently, this synergistic photocatalytic system greatly facilitated the successful degradation of NPX and the inactivation of E. coli under visible-light irradiation. Compared to the pure Bi2S3 and CoS2 catalysts, the Bi2S3/CoS2 (1:2) composites displayed significantly enhanced photodegradation activity, achieving 96.46% (k = 0.2847 min-1) degradation of NPX within 90 min and maintaining good recyclability with no significant decline after six successive cycles. Additionally, the photocatalytic inactivation of E. coli results indicated that Bi2S3/CoS2 composites exhibited excellent performance, leading to the inactivation of 7 log10 cfu mL-1 of bacterial cells after 150 min of visible-light exposure. Scanning Electron Microscopy (SEM) and K+ ions leakage tests demonstrated that the destruction of the E. coli cell membrane structure resulted in cell death. The outcomes of this work suggest that Bi2S3/CoS2 composites hold significant potential for treating water contaminated with antibiotic and microbial pollutants.

Analysis of a UV photocatalytic oxidation-based disinfection system for hydroxyl radicals, negative air ions generation and their impact on inactivation of pathogenic micro-organisms

This work presents a large-scale surface disinfection system, which has a unique lantern arrangement of ultraviolet-C (UV-C) light (254 nm) in conjunction with nanotechnology in a protective biosafety environment. Shadow regions are best dealt in this system by the generation of hydroxyl radicals (•OH) and negative air ions at sites where UV light cannot penetrate. More than 35 000 negative air ions/cm3 along with •OH were produced continuously in the disinfection chamber through the advanced photocatalytic oxidation process [UV-C + titanium dioxide (TiO2)]. The arrangement has been made to provide an optimized UV irradiation (∼2 mW/cm2) throughout the disinfection system. In order to distinguish between effects arising from (i) the action of UV dose alone and (ii) the action of UV dose along with •OH and negative air ions, E. coli and P. aeruginosa were chosen for bacterial testing and two interventions were made. The first intervention involved placing only UV lamps in the disinfection chamber to see the effect of only UV dose on bacterial inactivation efficiency. The second intervention involved placing the TiO2 nanoparticle coated aluminum plates along with UV lamps; this allows for the generation of negative air ions and •OH inside the disinfection chamber and enhanced bacterial inactivation efficiency. More than 95% bacterial inactivation efficiency has been reported in the case of UV-C + TiO2 compared to only 77% in UV only at the same time interval (90 s).

Construction of novel potentiometric sensors modified with biogenically synthesized metal oxide nanoparticles for sensitive detection of the opioid agonist-antagonist nalbuphine hydrochloride in its injection

Novel and sensitive potentiometric sensors were described for the assay of nalbuphine HCl (NBP) in authentic powder and injection samples. The developed sensors were modified with alumina nanoparticles (Al2O3NPs) and copper oxide nanoparticles (CuONPs). The nanoscale materials were synthesized using the extract of Salvia officinalis leaves in an environmentally friendly manner. The synthesized metal oxides were fully confirmed by various analytical techniques. Scanning electron microscope confirmed the morphology of nanosized materials with even distribution and particle size of 55.07 ± 4.15 and 59.48 ± 4.50 nm for Al2O3NPs and CuONPs, respectively. The modified sensors were prepared in three different steps. Nalbuphine hydrochloride was mixed with phosphomolybdic acid to prepare the sensor material nalbuphine phosphomolybdate (NBP-PM). It was then mixed with polyvinyl chloride in the presence of o-nitrophenyl ether and metal oxide nanoparticles to form the membrane matrix. Finally, a copper wire was coated with the sensing material. Excellent potentials of 1.0 × 10-8-1.0 × 10-2 and 1.0 × 10-9-1.0 × 10-2 mol L-1 were measured with lower assay limits of 4.8 × 10-9 and 5.0 × 10-10 mol L-1. The average detection % were 99.28 ± 0.58% and 99.52 ± 0.28% for NBP-PM-Al2O3NPs and NBP-PM-CuONPs, correspondingly. The suitability of the described sensors was investigated in terms of various validation criteria, and the modified sensors exposed excellent applicability and insurance for the quantification of nalbuphine hydrochloride in its bulk samples and injections compared with another standard sensor. It is obvious that the developed NBP-PM-Al2O3NPs and NBP-PM-CuONPs will serve as suitable sensors for the determination of NBP.

Polyethylene glycol and chitosan functionalized manganese oxide nanoparticles for antimicrobial and anticancer activities

Biocompatible polymer-functionalized magnetic nanoparticles could offer promising applications in biomedical sciences. We fabricated polymer functionalized tri-manganese tetra oxide (Mn₃O₄) nanoparticles with the co-precipitation method and an octahedral crystal structure having a crystallite size of 10-17 nm was identified via XRD analyses. The SEM graph depicted the non-uniform and smooth surface of PEG-functionalized Mn₃O₄ NPs as compared to Mn₃O₄ and chitosan-coated Mn₃O₄ NPs. Elemental composition in the prepared sample was examined by EDX analysis. Various modes such as MnO, MnOH, OH, symmetric, and anti-symmetric of CH₂ attached to the spectrum of Mn₃O₄ NPs were observed with FTIR analysis. The magnetization factor decreased and increase the coreacivity and retentivity of surface functionalized Mn₃O₄-NPs was calculated via VSM analysis. In-vitro bioassay, antibacterial activity was tested against Escherichiacoli, Bacillus cereus, and anti-fungal activities against two Fusarium strains indicated clear antimicrobial activities. The MTT assay to examine the anticancer activity against the MCF-7 cancer cell line was performed and the T₁ MRI contrast agent demonstrated that PEG-coated Mn₃O₄ NPs exhibited anti-cancer activities. We propose that surface-functionalized magnetic NPs used for the treatment of cancer by using a remote controlled process of hyperthermia therapy.

Dry-spun carbon nanotube ultrafiltration membranes tailored by anti-viral metal oxide coatings for human coronavirus 229E capture in water

Although waterborne virus removal may be achieved using separation membrane technologies, such technologies remain largely inefficient at generating virus-free effluents due to the lack of anti-viral reactivity of conventional membrane materials required to deactivating viruses. Here, a stepwise approach towards simultaneous filtration and disinfection of Human Coronavirus 229E (HCoV-229E) in water effluents, is proposed by engineering dry-spun ultrafiltration carbon nanotube (CNT) membranes, coated with anti-viral SnO2 thin films via atomic layer deposition. The thickness and pore size of the engineered CNT membranes were fine-tuned by varying spinnable CNT sheets and their relative orientations on carbon nanofibre (CNF) porous supports to reach thicknesses less than 1 µm and pore size around 28 nm. The nanoscale SnO2 coatings were found to further reduce the pore size down to ∼21 nm and provide more functional groups on the membrane surface to capture the viruses via size exclusion and electrostatic attractions. The synthesized CNT and SnO2 coated CNT membranes were shown to attain a viral removal efficiency above 6.7 log10 against HCoV-229E virus with fast water permeance up to ∼4 × 103 and 3.5 × 103 L.m-2.h-1.bar-1, respectively. Such high performance was achieved by increasing the dry-spun CNT sheets up to 60 layers, orienting successive 30 CNT layers at 45°, and coating 40 nm SnO2 on the synthesized membranes. The current study provides an efficient scalable fabrication scheme to engineer flexible ultrafiltration CNT-based membranes for cost-effective filtration and inactivation of waterborne viruses to outperform the state-of-the-art ultrafiltration membranes.

Metal Oxide Nanostructures (MONs) as Photocatalysts for Ciprofloxacin Degradation

In recent years, organic pollutants have become a global problem due to their negative impact on human health and the environment. Photocatalysis is one of the most promising methods for the removal of organic pollutants from wastewater, and oxide semiconductor materials have proven to be among the best in this regard. This paper presents the evolution of the development of metal oxide nanostructures (MONs) as photocatalysts for ciprofloxacin degradation. It begins with an overview of the role of these materials in photocatalysis; then, it discusses methods of obtaining them. Then, a detailed review of the most important oxide semiconductors (ZnO, TiO₂, CuO, etc.) and alternatives for improving their photocatalytic performance is provided. Finally, a study of the degradation of ciprofloxacin in the presence of oxide semiconductor materials and the main factors affecting photocatalytic degradation is carried out. It is well known that antibiotics (in this case, ciprofloxacin) are toxic and non-biodegradable, which can pose a threat to the environment and human health. Antibiotic residues have several negative impacts, including antibiotic resistance and disruption of photosynthetic processes.

Visible Light-Mediated Inactivation of H1N1 Virus UsingPolymer-Based Heterojunction Photocatalyst

It is well known that viruses cannot replicate on their own but only inside the cells of target tissues in the organism, resulting in the destruction of the cells or, in some cases, their transformation into cancer cells. While viruses have relatively low resistance in the environment, their ability to survive longer is based on environmental conditions and the type of substrate on which they are deposited. Recently, the potential for safe and efficient viral inactivation by photocatalysis has garnered increasing attention. In this study, the Phenyl carbon nitride/TiO₂ heterojunction system, a hybrid organic-inorganic photocatalyst, was utilized to investigate its effectiveness in degrading the flu virus (H1N1). The system was activated by a white-LED lamp, and the process was tested on MDCK cells infected with the flu virus. The results of the study demonstrate the hybrid photocatalyst's ability to cause the virus to degrade, highlighting its effectiveness for safe and efficient viral inactivation in the visible light range. Additionally, the study underscores the advantages of using this hybrid photocatalyst over traditional inorganic photocatalysts, which typically only work in the ultraviolet range.

Antiviral Activity of Zinc Oxide Nanoparticles against SARS-CoV-2

The highly contagious SARS-CoV-2 virus is primarily transmitted through respiratory droplets, aerosols, and contaminated surfaces. In addition to antiviral drugs, the decontamination of surfaces and personal protective equipment (PPE) is crucial to mitigate the spread of infection. Conventional approaches, including ultraviolet radiation, vaporized hydrogen peroxide, heat and liquid chemicals, can damage materials or lack comprehensive, effective disinfection. Consequently, alternative material-compatible and sustainable methods, such as nanomaterial coatings, are needed. Therefore, the antiviral activity of two novel zinc-oxide nanoparticles (ZnO-NP) against SARS-CoV-2 was investigated in vitro. Each nanoparticle was produced by applying highly efficient "green" synthesis techniques, which are free of fossil derivatives and use nitrate, chlorate and sulfonate salts as starting materials and whey as chelating agents. The two "green" nanomaterials differ in size distribution, with ZnO-NP-45 consisting of particles ranging from 30 nm to 60 nm and ZnO-NP-76 from 60 nm to 92 nm. Human lung epithelial cells (Calu-3) were infected with SARS-CoV-2, pre-treated in suspensions with increasing ZnO-NP concentrations up to 20 mg/mL. Both "green" materials were compared to commercially available ZnO-NP as a reference. While all three materials were active against both virus variants at concentrations of 10-20 mg/mL, ZnO-NP-45 was found to be more active than ZnO-NP-76 and the reference material, resulting in the inactivation of the Delta and Omicron SARS-CoV-2 variants by a factor of more than 10⁶. This effect could be due to its greater total reactive surface, as evidenced by transmission electron microscopy and dynamic light scattering. Higher variations in virus inactivation were found for the latter two nanomaterials, ZnO-NP-76 and ZnO-NP-ref, which putatively may be due to secondary infections upon incomplete inactivation inside infected cells caused by insufficient NP loading of the virions. Taken together, inactivation with 20 mg/mL ZnO-NP-45 seems to have the greatest effect on both SARS-CoV-2 variants tested. Prospective ZnO-NP applications include an antiviral coating of filters or PPE to enhance user protection.

Bacterial cellulose: Nano-biomaterial for biodegradable face masks - A greener approach towards environment

The use of face masks aids to stop the transmission of various deadly communicable ailments, and therefore widespread mask wearing habit is advocated by nearly all health organisations including the WHO to curb the COVID-19 pandemic. Recent studies predicted a shocking requirement of masks globally, approximately billions of masks per week in a single country, and maximum of them are disposable masks, which are made up of nonbiodegradable material such as polypropylene. With expanding review on improper masks disposal, it is imperative to perceive this inherent environmental hazard and avert it from resulting in the subsequent problematic situation due to plastic. The shift towards biodegradable biopolymers alternatives such as bacterial cellulose and newly evolving sustainable scientific knowledge would be significant to dealt with upcoming environmental problem. Bacterial cellulose possesses various desirable properties to replace the conventional mask material. This review gives an overview of data about accumulation of waste masks and its potential harm on environment. It also focuses on diverse characteristics of bacterial cellulose which make it suitable material for making mask and the challenges in the way of bacterial cellulose production and their possible solution. The current review also discussed the report on global bacterial cellulose market growth.

Inactivation of the enveloped virus phi6 with hydrodynamic cavitation

The COVID -19 pandemic reminded us that we need better contingency plans to prevent the spread of infectious agents and the occurrence of epidemics or pandemics. Although the transmissibility of SARS-CoV-2 in water has not been confirmed, there are studies that have reported on the presence of infectious coronaviruses in water and wastewater samples. Since standard water treatments are not designed to eliminate viruses, it is of utmost importance to explore advanced treatment processes that can improve water treatment and help inactivate viruses when needed. This is the first study to investigate the effects of hydrodynamic cavitation on the inactivation of bacteriophage phi6, an enveloped virus used as a SARS-CoV-2 surrogate in many studies. In two series of experiments with increasing and constant sample temperature, virus reduction of up to 6.3 logs was achieved. Inactivation of phi6 at temperatures of 10 and 20 °C occurs predominantly by the mechanical effect of cavitation and results in a reduction of up to 4.5 logs. At 30 °C, the reduction increases to up to 6 logs, where the temperature-induced increased susceptibility of the viral lipid envelope makes the virus more prone to inactivation. Furthermore, the control experiments without cavitation showed that the increased temperature alone is not sufficient to cause inactivation, but that additional mechanical stress is still required. The RNA degradation results confirmed that virus inactivation was due to the disrupted lipid bilayer and not to RNA damage. Hydrodynamic cavitation, therefore, has the potential to inactivate current and potentially emerging enveloped pathogenic viruses in water at lower, environmentally relevant temperatures.

Photoactive decontamination and reuse of face masks

The corona virus disease 2019 (COVID-19) pandemic has led to global shortages in disposable respirators. Increasing the recycling rate of masks is a direct, low-cost strategy to mitigate COVID-19 transmission. Photoactive decontamination of used masks attracts great attention due to its fast response, remarkable virus inactivation effect and full protection integrity. Here, we review state-of-the-art situation of photoactive decontamination. The basic mechanism of photoactive decontamination is firstly discussed in terms of ultraviolet, photothermal or photocatalytic properties. Among which, ultraviolet radiation damages DNA and RNA to inactivate viruses and microorganisms, and photothermal method damages them by destroying proteins, while photocatalysis kills them by destroying the structure. The practical applications of photoactive decontamination strategies are then fully reviewed, including ultraviolet germicidal irradiation, and unconventional masks made of functional nanomaterials with photothermal or photocatalytic properties. Their performance requirements are elaborated together with the advantages of long-term recycle use. Finally, we put forward challenges and prospects for further development of photoactive decontamination technology.

Surveillance of omicron variants through wastewater epidemiology: Latest developments in environmental monitoring of pandemic

WBE has been a monitoring system that can give purposeful and inclusive real-time assessments of civic society as well as environmental health. This concept review introduces WBE as a surveillance scheme and initial warning outbreaks of contagious diseases caused by harmful SARS-CoV-2 with pandemic potential. Examining biomarkers of contagious diseases as evidence in polluted water taken from wastewater treatment plants suggests that these systems can be examined to get epidemiological data for checking the transmission of infectious B.1.1.529 to different areas. Thereafter, various benefits of surveillance are provided to analyse health information and pinpoint different problems that may be occurring in the workstation. Surveillance is followed by intervention steps that improved the work environment and prevent further progression of the disease. This information will help to improve early detection strategies, designing a prevention strategy to reduce their spread, infection control and therapies, thus, strengthening our global preparedness to fight future epidemics. In the end, a comprehensive discussion on the remaining challenges and opportunities for epidemiology has been given for future research perspectives.

Recent advances in morphologically controlled synthesis of graphene oxide‐based nanocomposite as catalyst and fuel additive

Nanocomposites become very important because of their reduce size (1–100 nm), large surface area, excellent optical magnetic, and electrical and mechanical properties. In many applications, graphene oxide‐based metallic nanocomposites emerged as an outstanding class of nanomaterials that are used for different applications. (GO‐ZnO) nanocomposite has gained more importance in recent years. The present research study is designed to synthesize nanocomposites and aims to monitor its characteristics and applications. Graphene oxide is synthesized by Hummers' method. Metal salts are used as precursor source of respective metal oxides. Wet chemical synthesis method such as solvothermal/hydrothermal and copreciptation processes is used because of its low cost and easy applications as compared with other processes used in the past, which have been costly and difficult to handle. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques are used to discriminate GO‐Zinc oxide metallic nanocomposites. XRD is used to investigate the crystal structure, and SEM images showed that the synthesized GO/ZnO nanocomposites is irregular in shape with merged surfaces and the size is 100 nm−1 μm. The dark and light color shows hollow morphology of the nanocomposites, and particles are merged with each other and irregular in shape. The obtained data are statistically analyzed by using regression analysis for the further interpretations. VESTA, MATCH, Origin pro is used for the interpretation of XRD results of synthesized nanocomposites. Applications of metallic (GO/Zn) nanocomposite as catalytic activity and colorimetry, flash point, fire point, cloud point, pour point, specific gravity, and viscosity and for the degradation of Drimarene Red K‐4BL is performed.

Recent Advances on Metal Oxide Based Nano-Photocatalysts as Potential Antibacterial and Antiviral Agents

Photocatalysis, a unique process that occurs in the presence of light radiation, can potentially be utilized to control environmental pollution, and improve the health of society. Photocatalytic removal, or disinfection, of chemical and biological species has been known for decades; however, its extension to indoor environments in public places has always been challenging. Many efforts have been made in this direction in the last two–three years since the COVID-19 pandemic started. Furthermore, the development of efficient photocatalytic nanomaterials through modifications to improve their photoactivity under ambient conditions for fighting with such a pandemic situation is a high research priority. In recent years, several metal oxides-based nano-photocatalysts have been designed to work efficiently in outdoor and indoor environments for the photocatalytic disinfection of biological species. The present review briefly discusses the advances made in the last two to three years for photocatalytic viral and bacterial disinfections. Moreover, emphasis has been given to the tailoring of such nano-photocatalysts in disinfecting surfaces, air, and water to stop viral/bacterial infection in the indoor environment. The role of such nano-photocatalysts in the photocatalytic disinfection of COVID-19 has also been highlighted with their future applicability in controlling such pandemics.

Photocatalytic Degradation of Some Typical Antibiotics: Recent Advances and Future Outlooks

The existence of antibiotics in the environment can trigger a number of issues by fostering the widespread development of antimicrobial resistance. Currently, the most popular techniques for removing antibiotic pollutants from water include physical adsorption, flocculation, and chemical oxidation, however, these processes usually leave a significant quantity of chemical reagents and polymer electrolytes in the water, which can lead to difficulty post-treating unmanageable deposits. Furthermore, though cost-effectiveness, efficiency, reaction conditions, and nontoxicity during the degradation of antibiotics are hurdles to overcome, a variety of photocatalysts can be used to degrade pollutant residuals, allowing for a number of potential solutions to these issues. Thus, the urgent need for effective and rapid processes for photocatalytic degradation leads to an increased interest in finding more sustainable catalysts for antibiotic degradation. In this review, we provide an overview of the removal of pharmaceutical antibiotics through photocatalysis, and detail recent progress using different nanostructure-based photocatalysts. We also review the possible sources of antibiotic pollutants released through the ecological chain and the consequences and damages caused by antibiotics in wastewater on the environment and human health. The fundamental dynamic processes of nanomaterials and the degradation mechanisms of antibiotics are then discussed, and recent studies regarding different photocatalytic materials for the degradation of some typical and commonly used antibiotics are comprehensively summarized. Finally, major challenges and future opportunities for the photocatalytic degradation of commonly used antibiotics are highlighted.

Green aspects of photocatalysts during corona pandemic: a promising role for the deactivation of COVID-19 virus

The selection of a facile, eco-friendly, and effective methodology is the need of the hour for efficient curing of the COVID-19 virus in air, water, and many food products. Recently, semiconductor-based photocatalytic methodologies have provided promising, green, and sustainable approaches to battle against viral activation via the oxidative capabilities of various photocatalysts with excellent performance under moderate conditions and negligible by-products generation as well. Considering this, recent advances in photocatalysis for combating the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are inclusively highlighted. Starting from the origin to the introduction of the coronavirus, the significant potential of photocatalysis against viral prevention and -disinfection is discussed thoroughly. Various photocatalytic material-based systems including metal-oxides, metal-free and advanced 2D materials (MXenes, MOFs and COFs) are systematically examined to understand the mechanistic insights of virus-disinfection in the human body to fight against COVID-19 disease. Also, a roadmap toward sustainable solutions for ongoing COVID-19 contagion is also presented. Finally, the challenges in this field and future perspectives are comprehensively discussed involving the bottlenecks of current photocatalytic systems along with potential recommendations to deal with upcoming pandemic situations in the future.