Bacterial Disinfection Research Articles

Flower-like layered ZnO nanoflakes for cost-effective visible light-assisted photodynamic oxidation of tetracycline and bacterial disinfection

The conventional precipitation method was employed to synthesize the flower-like layered ZnO nano-flakes, characterized, and their photocatalytic potential was investigated for control of tetracycline antibiotics and high-strength pathogenic bacteria in wastewater effluent. Scanning electron microscope measurements confirm the formation of flower-like nano-flakes. Under white light, the catalytic efficiency of the ZnO nano-flakes is higher compared to blue light for the photocatalytic degradation of tetracycline, the inactivation of multidrug-resistant bacteria, and total coliforms. Under white light irradiation with the intensity of 80 mW/cm2, the ZnO nano-flakes showed the highest tetracycline degradation efficacy of 86 % within 120 min and complete inactivation of bacteria within 90 min without any additional oxygen sources. Scavenging experiments have clarified the photocatalytic mechanism of the degradation of tetracycline. The used catalyst was simply recovered by centrifugation (5 min) and could be reused without significant loss of photocatalytic activity. The remarkable efficiency and stability of the ZnO nano-flakes in this study mark a distinct approach to the development of heterogeneous photocatalysts for pollutant degradation. To evaluate the feasibility of a photocatalytic process for achieving consistent disinfection, microbial inactivation experiments were conducted using a batch-scale photocatalytic reactor with blue and white LEDs. The study targeted high-strength multidrug-resistant bacteria, including E. coli (Gram-negative) and S. aureus (Gram-positive), as well as total coliform in secondary effluent. This research clarifies the practical potential of ZnO nano-flakes for cost-effective photocatalytic oxidation treatment of wastewater pollutants.

Enhanced bacterial disinfection of multi-drug resistance bacteria by PCN@AgI heterojunction under visible light irradiation

Pathogenic bacterial infections have become a continuing threat to human health over the past decade, the development of novel antibacterial agents or strategies against drug-resistance bacteria is highly desirable. Although porphyrin-based metal organic frameworks (PCN) are important photosensitizers (PSs) for photodynamic antibacterial treatments, they are inefficient for killing gram-negative bacteria such as Escherichia coli. Herein, PCN@AgI heterojunction was prepared as a novel and potent multifunctional antibacterial agent to combat bacteria including drug-resistance bacteria such as extended-spectrum β-lactamaseEscherichia coli (ESBL) under visible light irradiation in vitro, attributing to the cooperation of the generated ROS and released Ag+ as well as GSH-depleting ability. Compared to pristine PCN, the formation of heterojunction between AgI and PCN facilitated the sufficient separation of the produced electron- hole pairs, leading to enhanced photocatalytic antibacterial capability by producing sufficient ROS. Furthermore, its GSH-depleting ability due to its oxidase-like behavior further boosted its antibacterial capability. Significantly, in vivo studies demonstrated that PCN@AgI heterojunction could promote the healing of E. coli-infected wound on rice back with high biosafety. These findings manifested that PCN@AgI heterojunction was a good potential antibacterial therapeutic agent and may hold promise in bacteria-infected wound healing.

Synthesis and characterization of Vs-B/MoS2 with double defects for efficient piezocatalytic antibiotic degradation and bacterial disinfection

Molybdenum disulfide (MoS2) is a promising piezoelectric catalytic material that has garnered extensive research attention. However, its application is hindered by its inherent centrosymmetric structure, leading to comparatively low piezoelectric efficiency. To address this issue, this study proposed a dual-defect (sulfur vacancies and boron-loaded) construction strategy to break the central symmetry of MoS2, and a series of Vs-B/MoS2 catalysts with ultrahigh piezoelectric catalytic efficiency were successfully prepared. The optimized Vs-B3.0/MoS2 catalyst exhibited exceptional piezoelectric catalytic activity, with a piezoelectric force microscopy (PFM) piezoelectric response amplitude of 403.9 pm and a piezoelectric coefficient of 35.1 pC N−1, which is 3.85 and 6.27 times higher than those of Vs-MoS2, respectively. Electrochemical tests and density functional theory calculations indicated that the enhanced piezoelectric performance can be attributed to boron doping and sulfur vacancy formation. These structural defects facilitate charge separation and increase material conductivity, significantly boosting piezoelectric properties. Within 60 min, the Vs-B3.0/MoS2 catalyst efficiently degraded 92.6 % of tetracycline. The electron paramagnetic resonance (EPR) characterization showed that ·OH and ·O2− were the main active radicals of the piezoelectric catalysis. In addition, the material exhibits significant bactericidal properties against E. coli. This study offers novel methods and technological support to enhance the piezoelectric properties of transition metal sulfides and efficiently purify water pollutants.

Hydrothermal synthesis, characterization of Co3Sb4O6F6 and carbon doped Co3Sb4O6F6 and their application towards photocatalytic dye degradation, adsorption, catalytic Knoevenagel condensation and bacterial disinfection

Single crystals of Co3Sb4O6F6 have been grown by employing hydrothermal techniques. Table sugar was utilized to prepare carbon-doped Co3Sb4O6F6. The objective was to employ Co(II)-based metal oxyfluoride comprising a stereochemically active lone pair element (Sb3+) and its carbon-doped analogues for the multifunctional applications. The impact of carbon doping on Co3Sb4O6F6 has been evaluated towards the changes in photocatalytic, catalytic, and adsorbent efficiency. The changes in carbon percentage affect the physical and chemical properties of the host material. A larger percentage of carbon doping turns the photocatalytic ability of the host material into an adsorbent for the removal of dye. The single crystal X-ray diffraction study reveals that Co3Sb4O6F6 crystallizes into cubic symmetry. However, powder X-ray diffraction study reveals the structural transformation in the carbon-doped Co3Sb4O6F6. It also reduces the band gap energy of the host material, and 4 wt% C@Co3Sb4O6F6 turns out to be an efficient photocatalyst. Large-scale carbon doping (15 wt%) appears to be an effective strategy to increase the surface charge and BET surface area, as consequences adsorption property develops in 15 wt% C@Co3Sb4O6F6/H2O2 for the elimination of methylene blue (MB). This favourable chemical adsorption process occurs with large maximum adsorption capacity (qmax = 58.41169 mg g-1), as evident from the Langmuir adsorption isotherm. Scavenger experiment confirms that the photocatalytic activities of the as-synthesised compounds were triggered by the active participation of the hydroxyl radical (.OH). The catalytic efficiencies of both parent and doped compounds are also established for the solvent-free Knoevenagel condensation reaction with 90 % yield at moderate temperature. Bacterial disinfection studies by the ‘Disc diffusion method’ confirm that Co3Sb4O6F6 shows better efficiency than the carbon doped compound against both Gram-positive and Gram-negative bacteria.

Green synthesis of Z-scheme N-doped g-C3N4/Nd-doped ZnO heterostructure by pomegranate waste peel with enhanced photocatalytic performance for organic pollutants removal and antibacterial activity

Nowadays, the growing global population and increased industrialization have exacerbated water pollution, posing a significant environmental threat. To tackle this issue, there is an urgent need for effective catalysts to remove pollutants. This study developed a novel N-doped g-C3N4/Nd-doped ZnO (NZ) heterostructure using a green approach by incorporating pomegranate peel waste as a stabilizing and capping agent. Characterization techniques confirmed successful NZ nanohybrid preparation. The synthesized NZ displayed high photocatalytic activity in degrading methylene blue (MB) and tetracycline (TC) pollutants found in wastewater, achieving degradation efficiencies of 95.3 % and 98.3 %, respectively. Meanwhile, it demonstrated satisfactory photostability after five-cycle experiments. The radical trapping experiments revealed that superoxide (O2−) and hydroxyl (OH) are the dominant active species and play an essential role in photocatalytic pollutant deterioration. Additionally, it exhibited suitable antimicrobial activity against Staphylococcus aureus and Vibrio cholerae bacterial strains. The enhanced performance is attributed to the abundant reaction sites of porous N-doped g-C3N4, the photo-redox capability of Nd-doped ZnO, and the efficient charge separation process in the Z-type heterojunction. This work advances sustainable and eco-friendly chemistry for the biosynthesis of organic/inorganic heterojunctions used in pollutant degradation and bacterial disinfection of wastewater.

Novel sustainable porous organic polymer for multifunctional water treatment: Adsorption and disinfection applications

The removal of dyes and bacteria from wastewater is crucial for environmental remediation and public health protection. The discharge of untreated wastewater containing dyes and bacteria can lead to water pollution, ecosystem disruption, and human health risks. In this context, we report the development of a sustainable gallic acid-based porous organic polymer (GA-azo-DADPM POP) for multifunctional water treatment applications. The polymer was characterized using 13C CP/MAS NMR, ATR-FTIR, SEM, and TEM, confirming its formation and revealing its agglomerate morphology, porous nature, and stacked sheet-like structure. The polymer exhibited a high BET surface area of 402 m2/g and a pore size distribution in the range of 2–20 nm, indicating its mesoporous nature. The adsorption studies demonstrated a maximum methylene blue dye removal capacity of 141.94 mg/g, while the antibacterial performance showed effective disinfection against E. coli. The adsorption studies followed the Freundlich isotherm and Pseudo second-order kinetic model. These results highlight the potential of GA-azo-DADPM POP for simultaneous dye removal and bacterial disinfection in wastewater treatment. In conclusion, this study demonstrates a novel, sustainable, and multifunctional material for water treatment, offering a promising solution for environmental restoration. The development of such materials can contribute significantly to the advancement of water treatment technologies, ensuring a safer and more sustainable future.

Artificial Bacteriophages for Treating Oral Infectious Disease via Localized Bacterial Capture and Enhanced Catalytic Sterilization.

With the rapid emergence of antibiotic-resistant pathogens, nanomaterial-assisted catalytic sterilization has been well developed to combat pathogenic bacteria by elevating the level of reactive oxygen species including hydroxyl radical (·OH). Although promising, the ultra-short lifetime and limited diffusion distance of ·OH severely limit their practical antibacterial usage. Herein, the rational design and preparation of novel virus-like copper silicate hollow spheres (CSHSs) are reported, as well as their applications as robust artificial bacteriophages for localized bacterial capture and enhanced catalytic sterilization in the treatment of oral infectious diseases. During the whole process of capture and killing, CSHSs can efficiently capture bacteria via shortening the distance between bacteria and CSHSs, produce massive ·OH around bacteria, and further iinducing the admirable effect of bacterial inhibition. By using mucosal infection and periodontitis as typical oral infectious diseases, it is easily found that the bacterial populations around lesions in animals after antibacterial treatment fall sharply, as well as the well-developed nanosystem can decrease the inflammatory reaction and promote the hard or soft tissue repair. Together, the high Fenton-like catalytic activity, strong bacterial affinity, excellent antibacterial activity, and overall safety of the nanoplatform promise its great therapeutic potential for further catalytic bacterial disinfection.

Alkaline phosphatase-activated prodrug system based on a bifunctional CuO NP tandem nanoenzyme for on-demand bacterial inactivation and wound disinfection

Nanozymes are promising antimicrobials, as they produce reactive oxygen species (ROS). However, the intrinsic lack of selectivity of ROS in distinguishing normal flora from pathogenic bacteria deprives nanozymes of the necessary selectivities of ideal antimicrobials. Herein, we exploit the physiological conditions of bacteria (high alkaline phosphatase (ALP) expression) using a novel CuO nanoparticle (NP) nanoenzyme system to initiate an ALP-activated ROS prodrug system for use in the on-demand precision killing of bacteria. The prodrug strategy involves using 2-phospho-L-ascorbic acid trisodium salt (AAP) that catalyzes the ALP in pathogenic bacteria to generate ascorbic acid (AA), which is converted by the CuO NPs, with intrinsic ascorbate oxidase- and peroxidase-like activities, to produce ROS. Notably, the prodrug system selectively kills Escherichia coli (pathogenic bacteria), with minimal influence on Staphylococcus hominis (non-pathogenic bacteria) due to their different levels of ALP expression. Compared to the CuO NPs/AA system, which generally depletes ROS during storage, CuO NPs/AAP exhibits a significantly higher stability without affecting its antibacterial activity. Furthermore, a rat model is used to indicate the applicability of the CuO NPs/AAP fibrin gel in wound disinfection in vivo with negligible side effects. This study reveals the therapeutic precision of this bifunctional tandem nanozyme platform against pathogenic bacteria in ALP-activated conditions.

Solvent-free synthesis of TiO2 nanoparticles embedded MWCNTs with enhanced photocatalytic activity for bacterial disinfection

Sustainable energy has been widely researched to address issues caused by population growth and rapid industrialization. Among them, photocatalysis using solar energy has been considered promising. We developed a hybrid photocatalyst by combining titanium dioxide (TiO2) with carbon nanotubes (CNTs), known for their excellent adsorption performance. A unique structure encapsulating TiO2 nanoparticles (NPs) within the inner space of multi-walled carbon nanotubes (MWCNTs) was developed via a facile, solvent-free method, conforming to green chemistry principles. Except purification and modification of the CNTs, the particle formation process is solvent-free, making this method remarkably simple and environmentally friendly. This arrangement enhances stability and recyclability, maintaining over 90 % efficiency up to the 3rd cycle. X-ray diffraction (XRD) analysis confirmed that the TiO2 NPs exhibited a crystalline phase, forming exclusively anatase. The defects in the outer walls of the MWCNTs in the composite, coupled with their large specific surface area and dangling bonds, endow them with high adsorption capacity and photocatalytic activity when combined with TiO2 NPs. The MWCNTs@TiO2 composites achieved over 99 % inactivation of Escherichia coli in 60 min and bacteriophage MS2 in 30 min, along with dye adsorption/decomposition. This method offers a distinctive platform for photocatalytic degradation in biological applications and water treatment.

Wind-induced vibration energy harvesters under base excitation: Analytical and numerical analysis

In this paper, analytical analysis of a wind-induced vibration energy harvester used for the bacterial disinfection of water is mainly considered. The complexification-averaging (CA) method is utilized to analytically calculate the results of the harvester, the model equations of the harvester satisfied are reduced into a set of complex variable equations. The relationship between the displacement amplitude and voltage amplitude is derived under the steady-state case. The amplitudes and phases of both the displacement and voltage are obtained. The analytical solutions of the harvester are then verified by direct numerical simulation. The response mechanism under different parameters is discussed. The frequency island and multi-valued phenomena are found. Meanwhile, it is found that a higher wind speed corresponds to a larger displacement amplitude and voltage. In addition, the RMS voltage and average power are studied. Both have the same variation rules under different excitation amplitudes. Under the same coupling coefficient, load resistance and piezoelectric patch capacitance, the lower the frequency, the easier it is to obtain the larger voltage output. However, the load resistance has the opposite effect on both of them. Finally, to obtain maximum output in a wider frequency region, the optimization and choice of the parameters is studied, and the critical boundary can be identified.

Enhanced bacterial and virus disinfection with copper nanoparticle optimized LIG composite electrodes and filters

Waterborne pathogens pose a lifelong threat, necessitating advanced disinfection systems with state-of-the-art materials. Laser-Induced Graphene (LIG), a 3-dimensional form of graphene, is a widely known electrode material for its electrically-induced antimicrobial properties. However, LIG surfaces exhibit antimicrobial properties exclusively in the presence of electricity. In this work, copper-doped LIG (Cu-LIG) composite electrodes and filters were developed with enhanced antimicrobial properties in single-step laser scribing. The work emphasizes the optimization of copper doping with LIG for both electrical and non-electrical-based disinfection. The copper doping was optimized to a minimal concentration (∼1%) just to enhance the electrochemical properties of LIG. Furthermore, the excess addition of copper was helpful towards non-electricity-based treatment without significant leaching. The prepared surfaces were tested in both electrodes and filter configuration and showed excellent antibacterial and antiviral activity against mixed bacterial culture and a model enteric virus, MS2 bacteriophage. On the application of 2.5 V with Cu-LIG electrodes, 6-log removal of bacteria and virus was achieved. Furthermore, the membrane-based electroconductive filters were tested in a flow-through configuration and demonstrated 6-log removal at 2.5 V with a flux of ∼ 500 L m2 h−1 with both bacteria and viruses at minimum energy expense. Additionally, reactive oxygen species scavenging and hydrogen peroxide generation experiments have confirmed the role of electrical effects and indirect oxidation on the inactivation mechanism. The prepared Cu-LIG composite surfaces showed potential for environmental remediation applications.

In-situ Hf/Zr co-doped Fe2O3 nanorod decorated with CuOx/CoOx: Enhanced photocatalytic performance for antibacterial and organic pollutants

Herein, we successfully synthesized Hf/Zr co-doping on Fe2O3 nanorod photocatalyst by a hydrothermal process and quenching methods. The synergistic roles of Hf and Zr double-doping on the bacteria inactivation test and decomposition of organic pollutants were investigated in detail for the 1 wt% CoOx loaded Hf/Zr–Fe2O3 NRs and CuOx/CoOx loaded Hf/Zr–Fe2O3 NRs photocatalyst. Initially, the rod-like porous morphology of the Hf/Zr-doped Fe2O3 NRs was produced via a hydrothermal method at various Hf co-doping (0, 2, 4, 7 and 10)%. Further, CoOx and CuOx loaded by a wet impregnation approach on the Hf/Zr–Fe2O3 NRs and a highly photoactive Hf(4)/Zr–Fe2O3 [CoOx/CuOx] NRs photocatalyst were developed. After the Hf(4)/Zr–Fe2O3 [CoOx/CuOx] NRs photocatalyst treatment, the Bio–TEM imagery of bacterial cells showed extensive morphological deviations in cell membranes. Hf(4)/Zr–Fe2O3 NR achieved 84.1% orange II degradation upon 3 h illumination, which is higher than that of Hf–Fe2O3 and Zr–Fe2O3 (68.7 and 73.5%, respectively). Additionally, the optimum sample, Hf(4)/Zr–Fe2O3 [CoOx/CuOx] photocatalyst, exhibited 95.5% orange II dye degradation after light radiation for 3 h. Optimized Hf(4)/Zr–Fe2O3 [CoOx/CuOx] catalysts exhibited 99.9% and 99.7% inactivation of E. coli and S. aureus with 120 min, respectively. Further, scavenger experiments revealed that the electrons are the primary responsible species for photocatalytic kinetics. This work will provide a rapid method for the development of high photocatalytic performance materials for bacterial disinfection and organic degradation.

Catalytic photo-degradation of brilliant green and bacterial disinfection of Escherichia coli by the action of Y2Ti2O7/AgO films

In this study, we evaluated the photocatalytic efficacy of pure Y2Ti2O7 films incorporating varying AgO ratios (1.0, 3.0, and 5.0 mol%) in the degradation process of brilliant green dye and in the bacterial disinfection of Escherichia coli under UV–visible illumination. The films were prepared utilizing a photochemical methodology involving β-diketonate complexes of Y(dbm)3, Ti(dbm)4, and Ag(acac) as starting materials. Following synthesis, the photo-deposits underwent calcination at 900 °C for 2 h and were subsequently analyzed using Fourier Transform Infrared Spectroscopy, X-Ray diffraction, Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectroscopy. The outcomes of these characterizations indicate the formation of a pyrochlore Y2Ti2O7 cubic phase, with the emergence of AgO in the doped samples. Photocatalytic performance yielded significant results, with a 94.9 % degradation of brilliant green observed for Y2Ti2O7 samples doped at 3.0 mol%, and a 98.4 % inhibition of Escherichia coli cultures observed for Y2Ti2O7 samples doped at 1.0 mol%. Theoretical calculations were employed to determine the band edge potentials of both oxides, supporting the establishment of a type I heterojunction between the Y2Ti2O7 phase and AgO. A degradation mechanism has been postulated based on assays involving the blocking of reactive oxygen species and charge carriers through the use of specific inhibitors.

Dynamic Ag-mediated electron transfer confined ZnO nanorods for boosted photocatalytic bacterial disinfection

Infectious diseases, particularly bacterial infections, pose a global crisis with significant impacts on public health and economic stability due to the emergence of multi-drug resistance and limitations in existing therapeutic options. The present study focused on the development of photocatalytic disinfectant and silver-decorated hexagonal zinc oxide nanorods (Ag/ZnO NRs) were fabricated through an ultrasonic-assisted solvothermal method, and investigated for the photocatalytic inactivation on E. coli. The morphological, structural, and optical characteristics of the fabricated Ag/ZnO NRs were systematically studied through various analytical techniques. Here, 3%Ag/ZnO NRs showed 96.9% inactivation of E. coli within 120 min of visible light irradiation. The excellent inactivation efficiency of the photocatalyst could be attributed to the higher charge carrier mobility, efficient electron-hole pair separation, and highvisible light harvesting ability. The Schottky heterojunction was proposed as a possible mechanism for the photoinactivation of E. coli. Further, the impacts of different dosages of nanocomposites (NCs) and varying pH on bacterial inactivation were studied under visible light exposure. The reusability and stability of the NCs were investigatedfor 6 consecutive cycles of photoinactivation and it showed excellent efficiency (91.16%) of the photocatalyst for prolonged usage. The real-time application was assessed using reclaimed wastewaterand the influence on the organic matter was determined using COD analysis. The proposed study offers a significant point reference for the practical application of photocatalysis forthe inactivation of antibiotic-resistant microbes present in water bodies and environmental wastewater.

Reuse of waste casein peptides to capture Cu (II) for long-term antibacterial reutilization

To date, researchers have worked on developing new pathways to control and manage food and industrial wastes (e.g. dairy wastewater, heavy metals, etc.), but most do not involve the reuse of these wastes. Herein, we propose to use casein peptides (CPs) based on dairy waste to capture Cu2+ from industrial wastewater, which is reduced to copper and cuprous oxide nanoparticles (consisting of metallic Cu and Cu2O crystalline phases) distributed on CPs. The prepared product CPs/Cu/Cu2O NPs showed prominent antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as multidrug-resistant bacteria from livestock wastewater through generating reactive oxygen species (ROS) in combination with released Cu2+. The method proposed in this study is also applicable to extract Cu2+ from actual electroplating wastewater for bacterial disinfection. Finally, we achieved the modulation of the composition of Cu/Cu2O NPs loaded on CPs.

Green synthesis of lichenan-decorated silver nanoparticles for catalytic hydrogenation of organic dyes and bacterial disinfection

Developing an eco-friendly and efficient homogeneous catalyst for treating complex wastewater containing toxic organic pollutants and bacteria is in significant demand. Herein, ultra-small Ag nanoparticles (NPs)-loaded random coil lichenan nanocomposite (L-AgNP) was prepared through a low-cost and green one-step in-situ reduction strategy using lichenan as the reducing agent. The random coil of lichenan acted as a micro-reactor to disperse and stabilize AgNPs via the Ag-O bonding interaction. In the participation of NaBH4, L-AgNP nanocomposite could achieve greater catalytic efficiency for catalyzing reduction of 4-nitrophenol (∼120 s, 34.34 × 10−3 s−1) with the smaller size of AgNPs or the higher content of Ag. The nanocatalyst also exhibited outstanding catalytic efficiency for congo red, rhodamine B, methylene blue, and methyl orange. The L-AgNP could be easily recycled through ethanol precipitation and continuously reused for ten cycles with a tiny loss of conversion rate. Furthermore, L-AgNP also displayed favorable antibacterial activity, inhibiting the growth of Escherichia coli and Staphylococcus aureus with more than 98 % disinfection ratio. This work provides a green strategy to develop polysaccharide-based multifunctional homogeneous catalysts focusing on wastewater purification.

The influence of pH on the efficacy of oxidation-reduction potential (ORP) to predict chlorine disinfection of surrogate bacteria, Escherichia coli O157:H7 and Listeria monocytogenes in oxidant demand free conditions and fresh produce wash water

Oxidation-reduction potential (ORP) is commonly used as a rapid measurement of the antimicrobial potential of free chlorine during industrial fresh produce washing. The current study tested the hypothesis that ORP can act as a “single variable” measurement of bacterial (vegetative and endospores) inactivation effectiveness with free chlorine irrespective of the water pH value. This situation has on occasion been assumed but never confirmed nor disproven. Chlorine-dosed pH 6.5 and 8.5 phosphate buffer solutions were inoculated with Escherichia coli (E. coli), Listeria innocua (L. innocua), or Bacillus subtilis (B. subtilis) endospores. ORP, free chlorine (FC), and log reduction were monitored after 5 s (for E. coli and L. innocua) and up to 30 min (for B. subtilis spores) of disinfection. Logistic and exponential models were developed to describe how bacteria reduction varied as a function of ORP at different pH levels. Validation tests were performed in phosphate buffered pH 6.5 and 8.5 cabbage wash water periodically dosed with FC, cabbage extract and a cocktail of Escherichia coli O157:H7 (E. coli O157:H7) and Listeria monocytogenes (L. monocytogenes). The built logistic and exponential models confirmed that at equal ORP values, the inactivation of the surrogate strains was not consistent across pH 6.5 and pH 8.5, with higher reductions at higher pH. This is the opposite of the well-known free chlorine-controlled bacterial inactivation, where the antibacterial effect is higher at lower pH. The validation test results indicated that in the cabbage wash water, the relationship between disinfection efficiency and ORP was consistent with the oxidant demand free systems. The study suggests that ORP cannot serve as a reliable single variable measurement to predict bacterial disinfection in buffered systems. When using ORP to monitor and control the antibacterial effectiveness of the chlorinated wash water, it is crucial to take into account (and control) the pH.

Internal piezoelectric field produced by tri-component (FTO: Sb-ZnO/MoS2) thin film for enhanced photocatalytic degradation of organic pollutants and antibacterial activity

The detection of organic dyes, pharmaceuticals, and microorganisms in the water environment continues to be a major concern worldwide. Hence, we report a novel method whereby a tri-component (Sb-ZnO/MoS2) immobilized on Fluorine-doped Tin Oxide (FTO) substrate for piezo-photocatalytic degradation of organic contaminants and bacterial disinfection. To determine the optical, electrochemical, physical, and chemical properties of the Sb-ZnO/MoS2, the following methods were applied, SEM & EDS, TEM, XRD, BET, UV-Vis DRS, PL, EIS and chronoamperometry. The SEM and TEM results showed long ZnO nanorods on the surface of stacked MoS2 nanosheets. Chronoamperometry studies showed that the Sb-ZnO/MoS2 tri-component exhibited a piezoelectric effect under ultrasonic vibration, indicating an internal piezoelectric field for inhibition of electrons and holes from recombination. According to PL studies, Sb-ZnO/MoS2 tri-component had a lower PL emission peak intensity, which suggests a better separation of electrons and holes. The developed tri-component was investigated for its catalytic degradation of methylene blue (MB), methyl orange (MO), and ciprofloxacin (CIP) under light and ultrasonic vibration. The coupling of light (photocatalysis) and ultrasonic irradiation (piezocatalysis) showed greater degradation efficiencies of 95, 82, and 72% for MB, MO, and CIP, respectively. The degree of mineralisation was recorded from total organic carbon (TOC) as 76, 70, and 52% for MB, MO, and CIP, respectively. In addition, Sb-ZnO/MoS2 tri-component was shown to have antibacterial activity against both E. coli and S. aureus bacterial strains. Therefore, this study reveals that the prepared Sb-ZnO/MoS2 tri-component can be applied for the simultaneous removal of dyes, pharmaceuticals, and disinfection of wastewater pollutants.

Disinfection of Bacteria in Aerosols by Applying High Voltage to Stranded Wire Electrodes.

The inactivation of airborne pathogenic microorganisms is crucial to attenuate the dissemination of infectious diseases induced by airborne pathogens. Conventional air disinfection methodologies, such as ultraviolet (UV) irradiation and ozone treatment, have demonstrated limited efficacy. Consequently, we investigated the potential of employing pulsed voltages to effectively eradicate bacteria within aerosols. Our inquiry revealed that the bacterial disinfection rate increased proportionally with elevated applied voltage and frequency. For instance, when a pulsed voltage of 20 kV and a frequency of 500 Hz were applied, a substantial disinfection rate exceeding 6.0 logarithmic units was attained. Furthermore, with the utilization of the stranded wire anodes, the disinfection intensity could be augmented by up to 2.0 logarithmic units compared with the solid wire configuration. Through the utilization of a stranded wire electrode model, we scrutinized the electric field encompassing the electrode, revealing a non-uniform electric field with the stranded wire electrode. This observation indicated an amplified bacterial disinfection effect, aligning with our experimental outcomes. These findings significantly enhance our comprehension of efficacious approaches to electrically disinfecting airborne bacteria.

Facile synthesis of porous graphitic carbon nitride modulated by up-conversion carbon quantum dots for visible light-triggered photocatalysis towards bacteria inactivation

In this work, novel porous g-C3N4 nanosheets modulated by up-conversion carbon quantum dots (CQDs/CNS) were successfully fabricated. Using the photocatalytic inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as the model reaction, the visible light-triggered antibacterial activity was evaluated. It was found that the photocatalytic performance towards bacterial inactivation is significantly improved, with the minimum inhibitory concentration (MIC) in CQDs/CNS against E. coli and S. aureus only being 12.5 and 40 ppm, respectively. The enhancement in antibacterial behavior can be attributed to the introduction of up-conversion CQDs. On the one hand, it extends absorption region to the visible light which promotes the generation of e- - h+ pairs. On the other hand, it narrows the energy band gap which accelerates the separation of carriers and transferance of charges at the interface. This study provides a new insight for developing a CQDs-based g-C3N4 system for effective bacterial disinfection.