Different inactivation behaviors and mechanisms of representative pathogens (Escherichia coli bacteria, human adenoviruses and Bacillus subtilis spores) in g-C3N4-based metal-free visible-light-enabled photocatalytic disinfection

Unveiling cutting-edge developments in defective BiOI nanomaterials: Precise manipulation and improved functionalities towards bolstered photocatalysis

Defect engineering represents a paradigm shift in tailoring nanomaterials for enhanced catalytic performance across various applications. This manuscript succinctly highlights the significance of defect engineering in improving the catalytic performance of BiOI nanoparticles for multiple applications, particularly in photocatalysis. The photocatalytic process of BiOI semiconductor is intricately linked to its indirect bandgap and layered crystalline structure. By influencing the structural dynamics of its layered materials, defects contribute significantly to optimizing its catalytic performance. "Fundamental insights into manipulating defects, including oxygen and iodine vacancies, bismuth defects, and synergistic dual defects, in BiOI are meticulously discussed. Advanced characterization techniques, spanning spectroscopy to microscopy, are explored for precise defect identification and quantification. The fragile van der Waals forces foster interactions between adjacent iodine atoms in BiOI, contributing to the overall structural stability". Understanding these structural intricacies lays a robust foundation for comprehending and exploring the exceptional physicochemical properties of two-dimensional BiOI. The manuscript showcases BiOI potential in energy and environmental sectors, ranging from solar-driven H2 evolution to CO2 reduction and various harmful pollutant degradation. By unravelling the intricate interplay between defects and catalytic activity, this manuscript sets a new benchmark for tailored catalytic solutions. This manuscript offers a comprehensive overview of defect engineering in BiOI and charts a path towards sustainable and efficient photocatalytic systems. It underscores the imperative of meticulous defect control and innovation in addressing the pressing challenges of the energy and environmental landscape.

Nanostructured copper-organic frameworks for the generation of sulphate radicals: application in wastewater disinfection

In recent years, the presence of pathogens in the environment has become an issue of widespread concern in society. Thus, new research lines have been developed regarding the removal of pathogens and persistent pollutants in water. In this research, the efficacy of nanostructure copper-organic framework, HKUST-1, has been evaluated for its ability to eliminate Escherichia coli and generate sulphate radicals as catalyst for the treatment of effluents with a high microbiological load via peroxymonosulphate (PMS) activation. The disinfection process has been optimized, achieving complete elimination of Escherichia coli growth after 30 min of testing using a concentration of 60.5 mg/L HKUST-1 and 0.1 mM of PMS. To overcome the operational limitations of this system and facilitate its handling and reutilization in a flow disinfection process, HKUST-1 has been efficiently encapsulated on polyacrylonitrile as a novel development that could be scaled up to achieve continuous treatment.

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.

Photobiocidal Activity of TiO2/UHMWPE Composite Activated by Reduced Graphene Oxide under White Light

Herein, we introduce a photobiocidal surface activated by white light. The photobiocidal surface was produced through thermocompressing a mixture of titanium dioxide (TiO2), ultra-high-molecular-weight polyethylene (UHMWPE), and reduced graphene oxide (rGO) powders. A photobiocidal activity was not observed on UHMWPE-TiO2. However, UHMWPE-TiO2@rGO exhibited potent photobiocidal activity (>3-log reduction) against Staphylococcus epidermidis and Escherichia coli bacteria after a 12 h exposure to white light. The activity was even more potent against the phage phi 6 virus, a SARS-CoV-2 surrogate, with a >5-log reduction after 6 h exposure to white light. Our mechanistic studies showed that the UHMWPE-TiO2@rGO was activated only by UV light, which accounts for 0.31% of the light emitted by the white LED lamp, producing reactive oxygen species that are lethal to microbes. This indicates that adding rGO to UHMWPE-TiO2 triggered intense photobiocidal activity even at shallow UV flux levels.

Effect of Human Adenovirus Type 35 Concentration on Its Inactivation and Sorption on Titanium Dioxide Nanoparticles

Removal of pathogenic viruses from water resources is critically important for sanitation and public health. Nanotechnology is a promising technology for virus inactivation. In this paper, the effects of titanium dioxide (TiO2) anatase nanoparticles (NPs) on human adenovirus type 35 (HAdV-35) removal under static and dynamic (with agitation) batch conditions were comprehensively studied. Batch experiments were performed at room temperature (25 °C) with and without ambient light using three different initial virus concentrations. The virus inactivation experimental data were satisfactorily fitted with a pseudo-first-order expression with a time-dependent rate coefficient. The experimental results demonstrated that HAdV-35 sorption onto TiO2 NPs was favored with agitation under both ambient light and dark conditions. However, no distinct relationships between virus initial concentration and removal efficiency could be established from the experimental data.

Disinfection of wastewater by a complete equipment based on a novel ultraviolet light source of microwave discharge electrodeless lamp: Characteristics of bacteria inactivation, reactivation and full-scale studies

Ultraviolet (UV) light is widely used for wastewater disinfection. Traditional electrode-excited UV lamps, such as low-pressure mercy lamps (LPUV), encounter drawbacks like electrode aging and rapid light attenuation. A novel UV source of microwave discharge electrodeless lamp (MDEL) has aroused attention, yet its disinfection performance is unclear and still far from practical application. Here, we successfully developed a complete piece of equipment based on MDELs and achieved the application for disinfection in wastewater treatment plants (WWTPs). The light emitted by an MDEL (MWUV) shared a spectrum similar to that of LPUV, with the main emission wavelength at 254 nm. The inactivation rate of Gram-negative E. coli by MWUV reached 4.5 log at an intensity of 1.6 mW/cm2 and a dose of 20 mJ/cm2. For Gram-positive B. subtilis, an MWUV dose of 50 mJ/cm2 and a light intensity of 1.2 mW/cm2 reached an inactivation rate of 3.4 log. A higher MWUV intensity led to a better disinfection effect and a lower photoreactivation rate of E. coli. When inactivated by MWUV with an intensity of 1.2 mW/cm2 and a dose of 16 mJ/cm2, the maximum photoreactivation rate and reactivation rate constant Kmax of E. coli were 0.63 % and 0.11 % h-1 respectively. Compared with the photoreactivation, the dark repair of E. coli was insignificant. The full-scale application of the MDEL equipment was conducted in two WWTPs (10,000 m3/d and 15,000 m3/d). Generally 2-3 log inactivation rates of fecal coliforms in secondary effluent were achieved within 5-6 s contact time, and the disinfected effluent met the emission standard (1000 CFU/L). This study successfully applied MDEL for disinfection in WWTPs for the first time and demonstrated that MDEL has broad application prospects.

Recent progress on bismuth-based light-triggered antibacterial nanocomposites: Synthesis, characterization, optical properties and bactericidal applications

Bacterial infections pose a seriously threat to the safety of the environment and human health. In particular, the emergence of drug-resistant pathogens as a result of antibiotic abuse and high trauma risk has rendered conventional therapeutic techniques insufficient for treating infections by these so-called "superbugs". Therefore, there is an urgent need to develop highly efficient and environmentally-friendly antimicrobial agents. Bismuth-based nanomaterials with unique structures and physicochemical characteristics have attracted considerable attention as promising antimicrobial candidates, with many demonstratingoutstanding antibacterial effects upon being triggered by broad-spectrum light. These nanomaterials have also exhibited satisfactory energy band gaps and electronic density distribution with improved photonic properties for extensive and comprehensive applications after being modified through various engineering methods. This review summarizes the latest research progress made on bismuth-based nanomaterials with different morphologies, structures and compositions as well as the different methods used for their synthesis to meet their rapidly increasing demand, especially for antibacterial applications. Moreover, the future prospects and challenges regarding the application of these nanomaterials are discussed. The aim of this review is to stimulate interest in the development and experimental transformation of novel bismuth-based nanomaterials to expand the arsenal of effective antimicrobials.

Synthesis and molecular docking study of α-aminophosphonates as potential multi-targeting antibacterial agents

Antibacterial compounds that reduce extracellular polymeric substances (EPS) are needed to avoid bacterial biofilms in water pipelines. Herein, green one-pot synthesis of α-aminophosphonates (α-Amps) [A-G] was achieved by using ionic liquid (IL) as a Lewis acid catalyst. The synthesized α-Amp analogues were tested against different bacteria such as Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. The representative [B] analogue showed an efficient antibacterial effect with MIC values of 3.13 μg/mL for E. coli, P. aeruginosa, and 6.25 μg/mL for B. subtilis. Additionally, a strong ability to eliminate the mature bacterial biofilm, with super-MIC values of 12.5 μg/mL for E. coli, P. aeruginosa, and 25 μg/mL for B. subtilis. Moreover, bacterial cell disruption by ROS formation was also tested, and the compound [B] revealed the highest ROS level compared to other compounds and the control, and efficiently destroyed the extracellular polymeric substances (EPS). The docking study confirmed strong interactions between [B] analogue and protein structures with a binding affinity of -6.65 kCal/mol for the lyase protein of gram-positive bacteria and -6.46 kCal/mol for DNA gyrase of gram-negative bacteria. The results showed that α-Amps moiety is a promising candidate for developing novel antibacterial and anti-biofilm agents for clean water supply.

Research Progress on Inactivation of Bacteriophages by Visible-Light Photocatalytic Composite Materials: A Mini Review

Infectious diseases caused by waterborne viruses have attracted researchers' great attention. To ensure a safe water environment, it is important to advance water treatment and disinfection technology. Photocatalytic technology offers an efficient and practical approach for achieving this goal. This paper reviews the latest studies on visible-light composite catalysts for bacteriophage inactivation, with a main focus on three distinct categories: modified UV materials, direct visible-light materials and carbon-based materials. This review gives an insight into the progress in photocatalytic material development and offers a promising solution for bacteriophage inactivation.

Efficient and sustainable photocatalytic inactivation of E. coli by an innovative immobilized Ag/TiO2 photocatalyst with peroxymonosulfate (PMS) under visible light

A novel catalytic system for effective photocatalytic inactivation of Escherichia coli (E. coli) was constructed by anchoring Ag nanoparticles (AgNPs) on silane coupling agent (SCA) pretreated TiO2 nano-tube arrays (Ag/SCA/TiO2NTAs). Morphology and structural analyses revealed that SCA could disperse AgNPs evenly on TiO2NTAs, thus inducing a superior surface plasmon resonance (SPR) effect. Ag/SCA/TiO2NTAs catalyst exhibited excellent inactivation performance when in the presence of peroxymonosulfate (PMS) and visible light (VL), with 6-log E. coli was completely inactivated within 60 min, which was 5.3, 12.5 and 13.2 times higher than that of Ag/SCA/TiO2NTAs/VL, PMS/VL and Ag/SCA/TiO2NTAs/PMS/dark systems, respectively. Additionally, the photocatalyst exhibited a highly reusable property, with the inactivation performance almost unchanged after ten cycles of uses with minimal Ag leaching. The inactivation mechanism analysis demonstrated that both radical (SO4•-, OH) and non-radical (h+, 1O2) pathways involved in E. coli inactivation, and SCA played a pivotal role in the production of reactive species. Chloride ions (Cl-) greatly enhanced the inactivation efficiency, while bicarbonate (HCO3-) and phosphate (H2PO4-) showed an inhibitory effect. Humic acid (HA) displayed a dual effect on inactivation performance, where the low concentration of HA facilitated the bacteria inactivation, while the higher dose suppressed bacteria inactivation. Moreover, the system exhibited excellent inactivation performance in tap water. This work first used SCA as the binder to fix AgNPs on TiO2NTAs for VL photocatalytic inactivation of bacteria with the assistance of PMS, which was expected to provide some insights into the practical treatment of drinking water.

Ultraviolet-based synergistic processes for wastewater disinfection: A review

Ultraviolet (UV) irradiation is widely used for wastewater disinfection but suffers from low inactivation rates and can cause photoreactivation of microorganisms. Synergistic disinfection with UV and oxidants is promising for enhancing the inactivation performance. This review summarizes the inactivation effects on representative microorganisms by UV/hydrogen peroxide (H₂O₂), UV/ozone (O₃), UV/persulfate (PS), UV/chlorine, and UV/chlorine dioxide (ClO₂). UV synergistic processes perform better than UV or an oxidant alone. UV mainly attacks the DNA or RNA in microorganisms; the oxidants H₂O₂ and O₃ mainly attack the cell walls, cell membranes, and other external structures; and HOCl and ClO₂ enter cells and oxidize proteins and enzymes. Free radicals can have strong oxidation effects on cell walls, cell membranes, proteins, enzymes, and even DNA. At similar UV doses, the inactivation rates of Escherichia coli with UV alone, UV/H₂O₂, UV/O₃, UV/PS (peroxydisulfate or peroxymonosulfate), and UV/chlorinated oxidant (chlorine, ClO₂, and NH₂Cl) range from 2.03 to 3.84 log, 2.62-4.30 log, 4.02-6.08 log, 2.93-5.07 log, and 3.78-6.55 log, respectively. The E. coli inactivation rates are in the order of UV/O₃ ≈ UV/Cl₂ > UV/PS > UV/H₂O₂. This order is closely related to the redox potentials of the oxidants and quantum yields of the radicals. UV synergistic disinfection processes inhibit photoreactivation of E. coli in the order of UV/O₃ > UV/PS > UV/H₂O₂. The activation mechanisms and formation pathways of free radicals with different UV-based synergistic processes are presented. In addition to generating HO·, O₃ can reduce the turbidity and chroma of wastewater to increase UV penetration, which improves the disinfection performance of UV/O₃. This knowledge will be useful for further development of the UV-based synergistic disinfection processes.

Integrated photocatalysis and moving bed biofilm reactor (MBBR) for treating conventional and emerging organic pollutants from synthetic wastewater: Performances and microbial community responses

Increasing concern for emerging organic pollutants (e.g. antibiotics) urges improvements in conventional biological wastewater treatment processes. This study examined the performance of an integrated photocatalysis and moving bed biofilm reactor (MBBR) system in treating synthetic wastewater containing sulfamethoxazole (SMX). It was found that the integrated system could remove over 80.5 % of SMX and 67.7-80.7 % of chemical oxygen demand (COD) with a hydraulic retention time of 24 h. The introduction of photocatalysis had no impact on COD removal and significantly enhanced SMX removal. High-throughput analysis indicated that microbial community greatly altered due to photocatalytic oxidation stress, with clostridiaceae and enterobacteriaceae becoming dominant families. Nevertheless, microorganisms maintained metabolic activity, which may be ascribed to the protection of carriers and microbial self-preservation by secreting extracellular polymeric substances and antioxidant enzymes. Collectively, this study sheds light on treating wastewater containing conventional and emerging organic pollutants by integrating photocatalysis with MBBR.

Continuous inactivation of human adenoviruses in water by a novel g-C3N4/WO3/biochar memory photocatalyst under light-dark cycles

Viruses transmitted by water have raised considerable concerns for public health. A novel memory photocatalyst of g-C₃N₄/WO₃/biochar was successfully developed for effective inactivation of human adenoviruses (HAdVs) in water, in which WO₃ as an electron-storage reservoir and biochar as an electron shuttle is employed to synergistically improve photocatalytic activity of g-C₃N₄. The tertiary composite exhibited continuous photocatalytic performance for HAdVs inactivation without regrowth in water under light-dark cycles, i.e., ∼3.9-log inactivation under 6-h visible light irradiation and an additional ∼1.1-log inactivation under the following 6-h dark. The enhanced virucidal mechanism was attributed to the heterojunction formation and especially the electron-transfer pathway switching via biochar incorporation, contributing to electron transfer and storage in the light phase and then electron release in the dark phase, along with obviously increased generation of the virus-killing •OH radicals under light-dark cycles.

A review on disinfection methods for inactivation of waterborne viruses

Water contamination is a global health problem, and the need for safe water is ever-growing due to the public health implications of unsafe water. Contaminated water could contain pathogenic bacteria, protozoa, and viruses that are implicated in several debilitating human diseases. The prevalence and survival of waterborne viruses differ from bacteria and other waterborne microorganisms. In addition, viruses are responsible for more severe waterborne diseases such as gastroenteritis, myocarditis, and encephalitis among others, hence the need for dedicated attention to viral inactivation. Disinfection is vital to water treatment because it removes pathogens, including viruses. The commonly used methods and techniques of disinfection for viral inactivation in water comprise physical disinfection such as membrane filtration, ultraviolet (UV) irradiation, and conventional chemical processes such as chlorine, monochloramine, chlorine dioxide, and ozone among others. However, the production of disinfection by-products (DBPs) that accompanies chemical methods of disinfection is an issue of great concern due to the increase in the risks of harm to humans, for example, the development of cancer of the bladder and adverse reproductive outcomes. Therefore, this review examines the conventional disinfection approaches alongside emerging disinfection technologies, such as photocatalytic disinfection, cavitation, and electrochemical disinfection. Moreover, the merits, limitations, and log reduction values (LRVs) of the different disinfection methods discussed were compared concerning virus removal efficiency. Future research needs to merge single disinfection techniques into one to achieve improved viral disinfection, and the development of medicinal plant-based materials as disinfectants due to their antimicrobial and safety benefits to avoid toxicity is also highlighted.

Inactivation behavior and intracellular changes in Escherichia coli during electro-oxidation process using Ti/Sb-SnO2/PbO2 anode: Elucidation of the disinfection mechanism

This study investigates the behavior and intracellular changes in Escherichia coli (model organism) during electro-oxidation with Ti/Sb-SnO₂/PbO₂ anode in a chlorine free electrochemical system. Preliminary studies were conducted to understand the effect of initial E. coli concentration and applied current density on disinfection. At an applied current density 30 mA cm^-2, 7 log reduction of E. coli was achieved in 75 min. The role of reactive oxygen species' (ROS) in E.coli disinfection was evaluated, which confirmed hydroxyl (•OH) radical as the predominant ROS in electro-oxidation. Observations were carried out at cell and molecular level to understand E.coli inactivation mechanism. Scanning electron microscopy images confirmed oxidative damage of the cell wall and irreversible cell death. Intracellular and extracellular protein quantification and genetic material release further confirmed cell component leakage due to cell wall rupture and degradation due to •OH radical interaction. Change in cell membrane potential suggests the colloidal nature of E. coli cells under applied current density. Plasmid deoxyribonucleic acid degradation study confirmed fragmentation and degradation of released genetic material. Overall, effective disinfection could be achieved by electro-oxidation, which ensures effective inactivation and prevents regrowth of E. coli. Disinfection of real wastewater was achieved in 12 min at an applied current density 30 mA cm^-2. Real wastewater study further confirmed that effective disinfection is possible with a low cost electrode material such as Ti/Sb-SnO₂/PbO₂. Energy consumed during disinfection was determined to be 4.978 kWh m^-3 for real wastewater disinfection at applied current density 30 mA cm^-2. Cost of operation was estimated and stability of the electrode was studied to evaluate the feasibility of large scale operation. Relatively low energy and less disinfection time makes this technology suitable for field scale applications.

Immobilized arginine/tryptophan-rich cyclic dodecapeptide on reduced graphene oxide anchored with manganese dioxide for microbial biofilm eradication

To avoid the accumulation of bacterial biofilms in water pipelines, it is critical to develop potent antimicrobial agents with good ability to reduce extracellular polymeric substances (EPS). In this study, cyclic dodecapeptides were synthesized, and different mutations for increasing the ratio of arginine (Arg) and tryptophan (Trp) were introduced. Separately, the synthesized dodecapeptides were immobilized on a reduced graphene oxide nanocomposite anchored with a hierarchical β-MnO₂ (RGO/β-MnO₂) hybrid. With a minimum inhibitory concentration of 0.97 g/mL, the immobilized Arg-Trp rich antimicrobial peptides (AMP) on RGO/MnO₂ nanocomposite, Cdp-4/RGO/MnO₂, showed superior efficacy against multidrug-resistant Pseudomonas aeruginosa ATCC 15692 (P. aeruginosa) planktonic cells. The immobilized Cdp-4/RGO/β-MnO₂ also eradicated the mature biofilm by 99% with a minimum inhibitory concentration value of 62.5 µg/mL with significant reduction of EPS. These characteristics allow the use of the immobilized Arg-Trp rich AMP as a promising antimicrobial agent against microbial biofilms, present in water distribution systems.

N, P, O co-doped carbon filling into carbon nitride microtubes to promote photocatalytic hydrogen production

Carbon nitride (CN) as the photocatalytic hydrogen production catalyst has attracted great attentions but suffering from a poor performance due to the unsatisfied energy band gap and the low separation efficiency of photogenerated carriers. Herein, we create a simple method to construct a novel CN-based photocatalyst, i.e., the N, P, O co-doped carbon filled CN microtube, which presents a narrow band gap, a high separation efficiency of photogenerated carriers, and a good stability. In this novel structure, the tubular morphology of CN ensures a narrow band gap, and the N, P, O co-doped carbon facilitates the transfer of photogenerated electrons. Coupling these two further reduces the energy band gap and improves the separation efficiency. For the photocatalytic hydrogen evolution under the visible light, the optimal sample presents an ultrahigh hydrogen evolution rate of 1149.71 μmol g^-1 h^-1 ranking at the top level, which is 112.60 times that of traditional bulk CN. In addition, it also has a high reusability and good stability after four cycle experiments. This study has provided a new viewpoint to design or develop the high-efficient photocatalysts for hydrogen production.

Intimately coupled photocatalysis and biodegradation for effective simultaneous removal of sulfamethoxazole and COD from synthetic domestic wastewater

The inefficiency of conventional biological treatment for removing sulfamethoxazole (SMX) is posing potential risks to ecological environments. In this study, an intimately coupled photocatalysis and biodegradation (ICPB) system consisting of Fe³⁺/g-C₃N₄ and biofilm was fabricated for the treatment of synthetic domestic wastewater containing SMX. The results showed that this ICPB system could simultaneously remove 96.27 ± 5.27% of SMX and 86.57 ± 3.06% of COD, which was superior to sole photocatalysis (SMX 100%, COD 4.2 ± 0.74%) and sole biodegradation (SMX 42.21 ± 0.86%, COD 95.1 ± 0.18%). Contributors to SMX removal in the ICPB system from big to small include LED photocatalysis, biodegradation, LED photolysis, and adsorption effect of the carrier, while COD removal was largely ascribed to biodegradation. Increasing initial SMX concentration inhibits SMX removal rate, while increasing photocatalyst dosage accelerates SMX removal rate, and both had no impact on COD removal. Our analysis of biofilm activity showed that microorganisms in this ICPB system maintained a high survival rate and metabolic activity, and the microbial community structure of the biofilm remained stable, with Nakamurella and Raoultella being the two dominant genera of the biofilm. This work provides a new strategy to effectively treat domestic wastewater polluted by antibiotics.

Inactivation efficacy and mechanism of pulsed corona discharge plasma on virus in water

The presence of viruses in water is a major risk for human and animal health due to their high resistance to disinfection. Pulsed corona discharge plasma (PCDP) efficiently inactivates bacteria by causing damage to biological macromolecules, but its effect on waterborne virus has not been reported. This study evaluated the inactivation efficacy of PCDP to viruses using spring viremia of carp virus (SVCV) as a model. The results showed that 4-log10 reduction of SVCV infectivity in cells was reached after 120 s treatment, and there was no significant difference in survival of fish infected with SVCV inactivated by PCDP for 240 s or more longer compared to the control fish without virus challenge, thus confirming the feasibility of PCDP to waterborne virus inactivation. Moreover, the high input energy density caused by voltage significantly improved the inactivation efficiency. The further research indicated that reactive species (RS) generated by pulsed corona discharge firstly reacted with phosphoprotein (P) and polymerase complex proteins (L) through penetration into the SVCV virions, and then caused the loss of viral infectivity by damage to genome and other structural proteins. This study has significant implications for waterborne virus removal and development of novel disinfection technologies.

TiO2-based nanomaterials assisted photocatalytic treatment for virus inactivation: perspectives and applications

The COVID 19 pandemic has demonstrated the need for urgent access to measures to contain the spread of the virus and bacteria. In this frame, the use of photocatalytic nanomaterials can be a valuable alternative to chemical disinfectants without the limitation of generating polluting by-products and with the advantage of re-usability in time. Here, on the basis of up-to-date literature reports, the use of TiO2-based photocatalytic nanomaterials in disinfection will be overviewed, considering the peculiar nanocatalysts assisted inactivation mechanisms. The potential of this class of photocatalysts for air, surface and water disinfection will be highlighted, critically revising the recent achievements in view of their potential in real application.

The synergistic effect of enhanced photocatalytic activity and photothermal effect of oxygen-deficient Ni/reduced graphene oxide nanocomposite for rapid disinfection under near-infrared irradiation

The rational design of high antibacterial efficiency are urgently needed as the occurrence of drug-resistance issues. Hence, Ni/reduced graphene oxide nanocomposite (Ni/rGO) with different amounts of oxygen vacancies were fabricated for efficient disinfection. The optimized Ni/rGO (A100) exhibited highly effective inactivation efficacy of 99.6% and 99.5% against Escherichia coli and Bacillus subtilis within 8 min near-infrared (NIR) irradiation through the synergistic effects of photothermal therapy and oxidative damage, which were much higher than single treatment. The A100 nanocomposite achieved an extraordinary photothermal conversion efficiency (35.78%) under the 808 nm irradiation for enhanced photothermal hyperthermia, thereby destroying the cell membrane and accelerating the GSH depletion. The radical scavenger experiment confirmed that •O₂^- and •OH play the chief role in photodisinfection reaction. Besides, A100 could exert significant damage on the ATP synthesis. The excellent photothermal performance and photocatalytic activity can be attributed to the appropriate oxygen vacancy density, which improves the absorption of NIR light and facilitates the separation of photogenerated electron-hole pairs. Besides, the higher NiO content of A100 contributed to improving the photocatalytic effect. Our work demonstrated a promising strategy for efficient water pollution purification caused by pathogenic bacteria.

A review on the potential of photocatalysis in combatting SARS-CoV-2 in wastewater

Photocatalytic technology offers powerful virus disinfection in wastewater via oxidative capability with minimum harmful by-products generation. This review paper aims to provide state-of-the-art photocatalytic technology in battling transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater. Prior to that, the advantages and limitations of the existing conventional and advanced oxidation processes for virus disinfection in water systems were thoroughly examined. A wide spectrum of virus degradation by various photocatalysts was then considered to understand the potential mechanism for deactivating this deadly virus. The challenges and future perspectives were comprehensively discussed at the end of this review describing the limitations of current photocatalytic technology and suggesting a realistic outlook on advanced photocatalytic technology as a potential solution in dealing with similar upcoming pandemics. The major finding of this review including discovery of a vision on the possible photocatalytic approaches that have been proven to be outstanding against other viruses and subsequently combatting SARS-CoV-2 in wastewater. This review intends to deliver insightful information and discussion on the potential of photocatalysis in battling COVID-19 transmission through wastewater.

Recent advances in graphite carbon nitride-based nanocomposites: structure, antibacterial properties and synergies

Bacterial infections and transmission threaten human health and well-being. Graphite carbon nitride (g-C₃N₄), a promising photocatalytic antibacterial nanomaterial, has attracted increasing attention to combat bacterial transmission, due to the outstanding stability, high efficiency and environmental sustainability of this material. However, the antibacterial efficiency of g-C₃N₄ is affected by several factors, including its specific surface area, rapid electron/hole recombination processes and optical absorption properties. To improve the efficiency of the antibacterial properties of g-C₃N₄ and extend its range of applications, various nanocomposites have been prepared and evaluated. In this review, the advances in amplifying the photocatalytic antibacterial efficiency of g-C₃N₄-based nanocomposites is discussed, including different topologies, noble metal decoration, non-noble metal doping and heterojunction construction. The enhancement mechanisms and synergistic effects in g-C₃N₄-based nanocomposites are highlighted. The remaining challenges and future perspectives of antibacterial g-C₃N₄-based nanocomposites are also discussed.