Active Chlorine Concentration Research Articles

Efficacy of preservation steps using super-oxidized water on vitamin C stability and prolonging the shelf-life of bok choy (Brassica rapa var chinesis)

ABSTRACT Leafy vegetables contain nutritious levels of vitamin C. Good postharvest management and food safety are the focus of reducing food loss. This study aims to evaluate the effectiveness of superoxide water in stabilizing the Vitamin C level and simultaneously prolonging the storage period for bok choy (Brassica rapa var. chinensis). The bok choy samples were immersed in superoxidised water [100 ppm Active chlorine concentration, neutral pH] and sodium bicarbonate solution for three different soaking periods: 5, 10, and 15 minutes and stored at 4°C. Weight loss, vitamin C, and chlorophyll content were evaluated during the 12 days of storage. The shelf life of bok choy treated with superoxidised water was extended from 3 days at room temperature to 8 days at 4°C. The results indicated that superoxidised water with a 5-minute treatment time could maintain a better quality of bok choy, which provides a cost-effective and sustainable alternative for chemical washing agents in the food industry compared to market-available sodium bicarbonate.

Formation behavior of PCDD/Fs during waste pyrolysis and incineration: Effect of temperature, calcium oxide addition, and redox atmosphere

The clean and efficient utilization of municipal solid waste (MSW) has attracted increasing concerns in recent years. Pyrolysis of MSW is one of the promising options due to the production of high-value intermediates and the inhibition of pollutants at reducing atmosphere. Herein, the formation behavior of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during MSW pyrolysis and incineration was experimentally investigated and compared. The influence of reaction temperature, CaO addition, and redox atmosphere on PCDD/Fs formation were compared and discussed. The results showed as the pyrolysis temperature increased, the mass concentration and international toxicity equivalence quantity of PCDD/Fs initially peaked at ∼750 °C before declining. Most of the generated PCDD/Fs were concentrated in the liquid and gaseous products, accounting for ∼90% of the total. Among liquid products, octachlorodibenzo-p-dioxin (O8CDD), 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,4,6,7,8-heptachlorodibenzofuran (H7CDF) were the most crucial mass concentration contributors, while in gas products, high-chlorinated PCDD/Fs, such as O8CDD, octachlorodibenzofuran (O8CDF) and 1,2,3,4,6,7,8-H7CDF were predominant. Compared to incineration, the formation of PCDD/Fs was 7–20 times greater than that from pyrolysis. This discrepancy can be attributed to the hydrogen-rich and oxygen-deficient atmosphere during pyrolysis, which effectively inhibited the Deacon reaction and the formation of C–Cl bonds, thereby reducing the active chlorine in the system. The addition of in-situ CaO additives also decreased the active chlorine content in the system, bolstering the inhibiting of PCDD/Fs formation during MSW pyrolysis.

Broad-Purpose Solutions of N-Chlorotaurine: A Convenient Synthetic Approach and Comparative Evaluation of Stability and Antimicrobial Activity

Solutions of N-chlorotaurine (NCT) are effective microbiocidal agents with a broad spectrum of pharmacological activity and outstanding tolerability. The main problem limiting their medical use is their instability, which is generally inherent in solutions of all chlorine-active compounds. In this work, we developed a new synthetic approach to the synthesis of such solutions, which consists in the activation of granular and fibrous polymeric materials with immobilized N-chlorosulfonamide groups, which act here as a chlorinating agent. It was shown that when such polymers are added to taurine solutions, NCT solutions with a chemical composition suitable for immediate medical use can be obtained. The stability of such solutions under various conditions was analyzed in comparison with NCTs obtained by the classical method from sodium hypochlorite. It was confirmed that the process of decomposition of all studied solutions obeys the kinetic laws of the first-order reaction. It was proven that solutions obtained from granular polymers are more stable both in terms of active chlorine concentration and in terms of pH, and their additional buffering is not needed. The stability of solutions decreases when they are stored in the presence of polymers used, with an increase in the excess of taurine and with acidification. The high sensitivity of all obtained solutions to UV radiation was also noted. The antimicrobial properties of NCT solutions obtained from polymers are not inferior to those obtained from sodium hypochlorite at the same concentration of active chlorine. Considering the stability and compactness of the initial chlorine-active polymers, as well as the possibility of their multiple regeneration, the developed method can form the basis of the technology for obtaining multifunctional NCT solutions for medical purposes with the desired physical and chemical properties without using special equipment or specific reagents.

Comparative Analysis of the Disinfection Efficiency of Steel and Polymer Surfaces with Aqueous Solutions of Ozone and Sodium Hypochlorite

Disinfection of surfaces with various functional purposes is a relevant measure for the inactivation of microorganisms and viruses. This procedure is used almost universally, from water treatment facilities to medical institutions and public spaces. Some of the most common disinfectants the World Health Organization recommends are chlorine-containing compounds. Sodium and calcium hypochlorites are only used for disinfection of the internal surfaces of water treatment facilities. However, it is known that ozone is a more powerful oxidizing agent. This study compares the effectiveness of inactivating yeast-like fungi Candida albicans, Gram-positive Bacillus subtilis, and Gram-negative bacteria Escherichia coli with aqueous ozone and sodium hypochlorite solutions. This study used ozone solutions in water with a concentration of 0.5–1.5 mg/L and sodium hypochlorite solutions with an active chlorine concentration of 50–150 mg/L. Steel and polymeric plates were used as substrates. Comparison of the CT (concentration by time) criterion at the ratio of LD50 in NaClO to ozonated water shows that the smallest difference, around 100 times, was observed in the inactivation of Candida albicans. The maximum difference is up to 230 times in the inactivation of Bacillus subtilis.

Synergistic mechanisms between chlorine-mediated electrochemical advanced oxidation and ultraviolet light for ammonia removal

The combination of chlorine-mediated electrochemical advanced oxidation (Cl-EAO) and ultraviolet (UV) radiation (UV-E/Cl) can efficiently remove ammonia from wastewater. However, the synergistic mechanisms between Cl-EAO and UV need to be explored in more detail. Thus, in this study, the ammonia oxidation performance of Cl-EAO and UV-E/Cl systems were compared, while the synergistic mechanisms were identified by the performance of UV/chlorine oxidation (UV–ClO) system and the results of electron paramagnetic resonance (EPR) analysis, free radical inhibition assays, and determination of steady-state concentration of free radicals. It was found that, compared with the Cl-EAO system, UV increased the ammonia removal rate by 42.85% and reduced the active chlorine concentration (56.64%) and nitrate yield (53.61%). In the Cl-EAO, and UV-E/Cl systems, Cl• were detected, and the free radical inhibition assays and determination of steady-state concentration of free radicals suggested that UV increased the concentration of Cl• by 51.47%, resulting in Cl• becoming the major contributor to ammonia oxidation in the UV-E/Cl system. Besides, UV also increase the concentrations of HO• and Cl2•-, which further promoted the organic matter removal in the real domestic wastewater. This study also discussed the ammonia oxidation performance of the UV-E/Cl system in real domestic wastewater, even with the presence of significant levels of organic and inorganic anions in the wastewater, UV increased the ammonia oxidation by 21.95%. The results of this study thus clarify the mechanisms and potential applications of UV-E/Cl technology.

Counterfactual Analysis of the Efficiency of Decontamination of Livestock Production Organic Wastes

Introduction. The implementation of the decree of the President of the Russian Federation is aimed at ensuring the food security of the country and requires the industrialization of the agro-industrial sector. The effectiveness of industrialization depends on the use of automated, intelligent solutions at all stages of implementing technological processes. Livestock is an agro-industrial sector generating the largest amount of organic waste materials, which are potential energy carriers: litter, liquid manure, process effluents, etc. According to the data from the Russian Statistics Committee and the research results, the annual volume of manure generated from farms is from 43.3 to 45.1 million tons, while there is an upward trend. The used energy potential from the entire volume does not exceed 40%. It is possible to increase the efficiency of using the energy potential of organic animal waste materials through implementing digitalized solutions. A strategic tool for the effective industrialization of livestock is the implementation of application software products that ensure the growth of ecological and energy effects. Aim of the Article. The aim of the study is a counterfactual evaluation of the efficiency of the model for decontaminating liquid pig manure in the decontamination activator. Materials and Methods. Counterfactual analysis is a tool for formalizing complex, multifactorial processes to ensure their subsequent digitalization. The essence of the analysis consists in a “surveyˮ of the analyzed model through which the values of variables are determined providing changes that lead to a deviation of the response beyond the boundary conditions during interpretation. The advantage of counterfactual analysis is the stability and transparency of the model to external influences during machine learning. It is known that the representative pathogenic markers of the decontamination efficiency of liquid pig manure are helminth eggs and the number of colony-forming units of common coliform bacteria (CFU CCB). However, for testing and implementing an algorithm for counterfactual analysis of a mathematical model, it is acceptable to use the number of CFU CCB. The object of the study was liquid pig manure with a humidity from 88% to 98%, the subject was a counterfactual analysis of the dependence of the number of CFU CCB on the exposure time in the activator, the concentration of active chlorine, the mass of working bodies, magnetic induction, and liquid manure humidity. Results. The results of counterfactual evaluation and analysis carried with the use of the Python programming language and the PyCharm 2022.2 environment are presented in the tables. The counterfactual evaluation made it possible to identify ranges of variation of factors, the use of which can represent the potential of boundary conditions in solving the optimization problem. The cells of these values are highlighted in grey-blue. The most preferred ranges based on counterfactual evaluation are in the cells highlighted in green. Discussion and Conclusions. There has been substantiated the prospects of using active chlorine in combination with the influence of ferromagnetic working bodies moving in an alternating rotating electromagnetic field as a decontamination activator. On the basis of counterfactual evaluation it was established that the most significant factors for determining the efficiency of decontamination of liquid pig manure by the number of CFU CCB are: magnetic induction in the working zone of the activator inductor, active chlorine concentration and exposure time.

Inactivation of human coronaviruses using an automated room disinfection device

The emergence of more virulent and epidemic strains of viruses, especially in the context of COVID-19, makes it more important than ever to improve methods of decontamination. The objective of this study was to evaluate the potential of on-demand production of chlorine species to inactivate human coronaviruses. The commercial prototype disinfection unit was provided by Unipolar Water Technologies. The Unipolar device generates active chlorine species using an electrochemical reaction and dispenses the disinfectant vapour onto surfaces with an aspirator. The minimum effective concentration and exposure time of disinfectant were evaluated on human hepatoma (Huh7) cells using 50% tissue culture infectious dose (TCID50) assay and human coronavirus 229E (HCoV-229E), a surrogate for pathogenic human coronaviruses. We showed that chlorine species generated in the Unipolar device inactivate HCoV-229E on glass surfaces at ≥ 400 parts per million active chlorine concentration with a 5 min exposure time. Here, inactivation refers to the inability of the virus to infect the Huh7 cells. Importantly, no toxic effect was observed on Huh7 cells for any of the active chlorine concentrations and contact times tested.

N-Halamine-Based Polypropylene Melt-Blown Nonwoven Fabric with Superhydrophilicity and Antibacterial Properties for Face Masks.

Polypropylene melt-blown nonwoven fabric (PP MNF) masks can effectively block pathogens in the environment from entering the human body. However, the adhesion of surviving pathogens to masks poses a risk of human infection. Thus, embedding safe and efficient antibacterial materials is the key to solving pathogen infection. In this study, stable chlorinated poly(methacrylamide-N,N'-methylenebisacrylamide) polypropylene melt-blown nonwoven fabrics (PP-P(MAA-MBAA)-Cl MNFs) have been fabricated by a simple UV cross-link and chlorination process, and the active chlorine content can reach 3500 ppm. The PP-P(MAA-MBAA)-Cl MNFs show excellent hydrophilic and antibacterial properties. The PP-P(MAA-MBAA)-Cl MNFs could kill all bacteria (both Escherichia coli and Staphylococcus aureus) with only 5 min of contact. Therefore, incorporating PP-P(MAA-MBAA)-Cl MNF as a hydrophilic antimicrobial layer into a four-layer PP-based mask holds great potential for enhancing protection and comfort.

High-strength hydrophilic N-halamines chitosan and cellulose nanofibers membranes with repeated bactericidal properties

Direct addition of disinfectants and membrane separation techniques have been common methods to address microbial contamination in water. However, disinfectants may generate toxic by-products, and even minor damage or biofilm formation on filtration membranes can lead to a heightened risk of microbial contamination. Consequently, how to quickly and safely disinfect microbial contaminated water sources remains a huge challenge. In this study, the high-strength broad-spectrum antibacterial CNF/CS composite membrane was fabricated by utilizing cellulose nanofibers (CNF) to reinforce the structure of chitosan (CS). The resulting CNF/CS composite membrane exhibits an impressive tensile strength of 148 MPa and boasts an active chlorine content of 5.29 %. Notably, even after undergoing 50 washing cycles and 10 repeated chlorination procedures, the structural integrity and high active chlorine content of the composite membrane remain preserved, validating its exceptional strength, stability, and chlorine rechargeability. Additionally, the CNF/CS antibacterial materials demonstrate remarkable attributes in terms of rapid sterilization, sustained and consistent release of active chlorine, and efficient inhibition of biofilm formation, demonstrating great potential in efficient, green, and safe sterilization.

Transformation behavior of the ultraviolet absorbent 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328) in polyethylene plastic under chlorination

In plastic, a 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328) ultraviolet light absorber is a common additive. When using sodium hypochlorite (NaClO) to disinfect plastic, UV328 may react with NaClO. For this work, we investigated the transformation behavior of UV328 in polyethylene (PE) plastic by NaClO. The reaction rate increased with the initial free active chlorine (OCl−) concentration and the decrease of the initial UV328 concentration. At room temperature (25 °C) to lower temperatures (0 °C), OCl− could transform UV328, and the reaction activation energy was fitted as 31.10 kJ/mol. Replacement of the plastic carrier (change to polypropylene) had no effect on the reaction process. A total of 12 intermediates were identified, and calculations based on density functional theory (DFT) were used to assist in rationalizing the product structure. Chlorination, hydroxylation, coupling, and bond cleavage were speculated as the main transformation pathways. Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were the only two measured disinfection by-products in the system, and their concentration were 18.33 and 18.19 μg/g, respectively. The toxicity prediction by Toxicity Estimation Software Tool (T.E.S.T) illustrated that the toxicity of the transformation products was higher overall than that of UV328 during the reaction. This work can help to deepen the understanding of the transformation behavior of UV328 in PE plastic in NaClO solution.

Formation of biosafety and greening of the production environment of food production with application of anolyte

Introduction: Electrochemically activated aqueous solutions are widely used in medical institutions, animal husbandry, as well as in large food processing facilities. This work presents a literature review on the use of electrochemically activated solutions in the food industry. These solutions can be used as a safe means for processing food raw materials, equipment, food containers, and surfaces of foodservice facilities. The question of using activated aqueous solutions in relation to foodservice establishments is not fully explored in the scientific literature.Purpose: The aim of the research is to study the possibility of using electrochemically activated aqueous solutions as safe and environmentally friendly means for treating objects in the production environment to eliminate the risk of contamination by microorganisms.Materials and Methods: Surfaces of the production environment were selected as the objects of study, including a table, scales, a knife, a slicer, and a gastronorm container. Sweet pepper fruits of the "Avangard" variety were chosen as non-heat-treated food products. An electrochemically activated aqueous solution of chlorine dioxide and hydrogen peroxide compounds with a concentration of active substances of 0.5 ± 0.05 g/L (Anolyte ANK-SUPER) was chosen as the treatment agent. Microbiological studies were conducted using XLD Agar medium and petrifilms. To assess the effectiveness of treatment, microbiological studies were conducted with the determination of Coliform Bacteria (BGKP) and Mesophilic Aerobic and Facultative Anaerobic Microorganisms (KMAFAnM). To achieve acceptable microorganism counts for counting purposes, the tenfold dilution method was used. The residual active chlorine concentration was determined using the iodometric method to determine the actual concentrations of working solutions.Results: The use of undiluted disinfectant with a concentration of 0.5 ± 0.05 g/L confirmed the effectiveness of electrochemically activated solutions against Coliform Bacteria (BGKP), with a significant reduction in the content of Mesophilic Aerobic and Facultative Anaerobic Microorganisms (KMAFAnM) compared to control samples. However, the results of the experiments suggest that parameter selection is required, specifically the concentration of the disinfectant and the duration of treatment depending on the object. The data obtained from preliminary experiments characterize the potential use of reduced concentrations of the working solution (no less than 0.05 ± 0.005 g/L of active chlorine), but do not confirm the possibility of full-scale application of the used concentrations due to the lack of quantitative data on the degree of contamination of the initial surfaces. The possibility of using the solutions as a single agent for treating both working surfaces and fruit and vegetable products has been demonstrated.Conclusion: As a result of the conducted research, the effectiveness of disinfectants based on electrochemically activated solutions against Escherichia coli bacteria (BGKP) and the reduction of Mesophilic Aerobic and Facultative Anaerobic Microorganisms (KMAFAnM) has been confirmed. In addition, among the possible prospects for research, determining the minimum concentrations and contact times for achieving stable disinfecting effects can be mentioned. The results obtained showed that the use of electrochemically activated solutions ensured the biological safety of treated production objects and surfaces of thermally untreated food products. An alternative method of using electrochemically activated solutions as a universal environmentally friendly agent has been proposed. Thus, in foodservice establishments, an effective "green" technology based on electrochemically activated solutions can be implemented.

Durable and rechargeable antimicrobial cotton driven by enhanced UV stability and real-time detection of biocidal factors

In this study, graphene oxide/N-halamine nanocomposite was synthesized through Pickering miniemulsion polymerization, which was then coated on cotton surface. The modified cotton exhibited excellent superhydrophobicity, which could effectively prevent microbial infestation and reduce the probability of hydrolysis of active chlorine, with virtually no active chlorine released in water after 72 h. Deposition of reduced graphene oxide nanosheets endowed cotton with ultraviolet-blocking properties, attributing to enhanced UV adsorption and long UV paths. Moreover, encapsulation of polymeric N-halamine resulted in improved UV stability, thus extending the life of N-halamine-based agents. After 24 h of irradiation, 85 % of original biocidal component (active chlorine content) was retained, and approximately 97 % of initial chlorine could be regenerated. Modified cotton has been proven to be an effective oxidizing material against organic pollutants and a potential antimicrobial substance. Inoculated bacteria were completely killed after 1 and 10 min of contact time, respectively. An innovative and simple scheme for determination of active chlorine content was also devised, and real-time inspection of bactericidal activity could be achieved to assure antimicrobial sustainability. Moreover, this method could be utilized to evaluate hazard classification of microbial contamination in different locations, thus broadening the application scope of N-halamine-based cotton fabrics.

INFLUENCE OF ELECTROCHEMICALLY ACTIVATED SOLUTIONS ON THE FATTY ACID PROFILE OF FOOD SYSTEMS

The emergence of new types and methods of food processing requires studying the impact on the compo-nents of food systems. Fish products are an important part of the human diet, but as a result of storage, their quality and safety indicators are reduced. An effective way to ensure the biological safety of fish raw materials is the use of electrochemically activated solutions (ECAS) obtained by high-voltage diaphragm electrolysis. The aim of the study was to study the effect of various concentrations of ECAS on the fatty acid profile of food systems using the example of fish oil from Atlantic salmon (Salmo salar) fillet during the shelf life. In the experiments, a ready-made ECAS with an active chlorine concentration (hereinafter Cach) of 500 mg/l (0.05%) was used, from which working ECAS were prepared with a dilution of 50% and 15%, which corresponds to Cach – 250 mg/l (0.025%) and Cach – 75 mg / l (0.0075%). The concentration of ECAS was selected experimentally in order to determine the optimal concentration at which the de-struction of fatty acids (hereinafter FA) of the studied samples did not occur. The determination was car-ried out by gas chromatography using a Crystal-2000M chromatograph. Comparison was made with con-trol samples. Identification of the peaks of FA methyl esters of the tested samples made it possible to de-termine the recommended working concentration of active chlorine ECAS equal to 75 mg/l, at which the content of polyunsaturated fatty acids does not statistically decrease. The research results can be used to ensure the quality and biological safety of fish fillets, taking into account the specific effects of ECAS on individual components of food systems.

Безопасность использования в практике дезинфицирующих средств на основе гипохлорита натрия

The parameters of toxicometry of disinfectants based on sodium hypochlorite obtained by chlorination of an aqueous solution of caustic soda (31 agents) and by electrochemical method – 10 anoliths were established. Based on the determination of the chlorine content in the air, recommendations are given for the safe use of these disinfectants: for surface treatment by wiping and disinfection of air and surfaces by aerosol spraying using a special device – an aerosol generator that provides dispersion of aerosol particles of 5–50 microns. A working solution of sodium hypochlorite with an active chlorine content of 0.015?% is recommended for use by wiping in the presence of people. Keywords: disinfectants, sodium hypochlorite, anolytes, toxicity, irritant effect, inhalation hazard, aerosol, laboratory animals.

Durable and biocompatible antibacterial N-halamine membranes based on cellulose carbamate

Increasing attention had been paid to the antibacterial and safety properties of membrane materials. The cellulose carbamate membrane (RCCM) without antibacterial properties would limit its applications in the food packaging industry. Herein, the antibacterial N-halamine regenerated cellulose carbamate membrane (RCCM-Cl) was manufactured by sodium hypochlorite solution treating the inherent amide of RCCM. The chemistry and mechanics properties of RCCM and RCCM-Cl were investigated. The antibacterial properties, cell compatibility, rechargeability and durability stability of RCCM-Cl were evaluated. Results demonstrated that the functional RCCM-Cl exhibits remarkable antibacterial activity which could sterilize Escherichia coli and Staphylococcus aureus within 1 min in the first contact period. The breaking strength, elongation at breaking, and transparency of RCCM-Cl retained 148.6 MPa, 8.1%, and 94%, respectively. In addition, antibacterial RCCM-Cl with active chlorine content exhibits excellent cell compatibility, regenerability, storage stability and stability in water.

Monitoring of On-Site generated Hypochlorite for Water Disinfection

The aim of this study was to better evaluate the impact of on-site electro-generated hypochlorite for water disinfection. For this venture, the daily variability of hypochlorite-generating systems and their performance to produce low disinfection by-products during the formation of hypochlorite were observed. Seven on-site electro-generated hypochlorite installations, were selected at different swimming pool facilities in Switzerland. Active chlorine (AC), the two disinfection by-products chlorate (ClO3-) and perchlorate (ClO4-), and the pH were monitored over several hours. All monitored installations produced significant concentrations of chlorate, related to the measured active chlorine concentration. The median chlorate concentrations ranged between 1.4 to 76.9 µg ClO3-/mg AC during daily monitoring. Perchlorates have been detected only in the installations of one brand that generated concentrations up to 34.9 µg ClO4-/mg AC. For all installations, pH was lower than expected with a median pH of 9.6. Some samples presented even surprisingly acidic pH leading to possible sample degradation. This study clearly shows the weakness of a one-shot sampling to evaluate the quality of on-site electro-generated hypochlorite systems, due to high daily process variations. Additionally, the evaluation of the influence of three process parameters has pointed out that including chlorate aspects during the optimisation stage of on-site generated hypochlorite may significantly reduce chlorate contamination during water disinfection.

Synthetic polyurethane nanofibrous membrane with sustained rechargeability for integrated air cleaning

Health problems caused by airborne particulate matter (PM) and bacteria have placed a severe burden on public health. At present, most personal protective equipment focused on PM filtration but ignored the threat from pathogens like bacteria in the air. Moreover, the disposable protective items such as masks used in large quantities have caused great pollution issues. Hence, in this study, a fresh polyurethane nanofibrous membrane (named as PU/PIU-Cl) was synthesized with imidazolidinyl urea groups as block components for enhanced biocidal effect which not only has extremely high filtration efficiency (up to 99.92%) against particulate pollutants, but also excellent intrinsic antibacterial ability (>99%) and safety, indicating its remarkable performance for integrated air pollution control. Furthermore, the antibacterial ability of the membrane can be facilely regenerated by re-chlorination, and the active chlorine content of PU/PIU-Cl membrane through halogenation hardly decreased after five cycles. Therefore, the PU/PIU-Cl nanofibrous membrane can not only be used as protective equipment, such as masks with sterilization function, but also can effectively alleviate the pollution problem of disposable protective products. • Imidazolidinyl urea groups are employed as block components of polyurethane. • PU/PIU-Cl exhibits intrinsic antibacterial function and high filtration efficiency. • PU/PIU-Cl is low cytotoxic, low cost and reusable, and shows great potential in PPE.

Long-lasting renewable antibacterial graphene/N-halamine-coated cotton fabrics benefitting from enhanced UV stability and quantitative tracking of bactericidal factors

In this study, anionic GO aqueous dispersion and cationic QAS aqueous solution with specific concentrations were applied for the fabrication of modified cotton fabrics (MCFs) through the layer-by-layer self-assembly method. The chlorinated cotton fabrics with optimized protocol possessed excellent ultraviolet-blocking properties, with a UPF value of 323.08. Moreover, graphene greatly improved the UV stability of N-halamine, which could also be proved in the UV aging test of MCFs. In addition, the modification procedure also endowed cotton fabrics with superhydrophobic properties, thus broadening the application range of cotton fabric. The obtained GQC10 possessed excellent antibacterial activity, with all inoculated S. aureus and E. coli O157:H7 being completely killed within 5 min and 1 min of contact time, respectively. Indicated by the quantitative function relation between the active chlorine content (ACC) and the surface sheet resistance (SSR) of the MCFs, a novel and simple method for the determination of ACC was established. This method could be used to monitor the antimicrobial efficacy to ensure its sustainability. Furthermore, according to the variation frequency of SSR, the risk level of bacterial hazards in different places could be evaluated, thus broadening the application range of N-halamine-based antibacterial cotton fabrics.

Polyvinylidene fluoride multi-scale nanofibrous membrane modified using N-halamine with high filtration efficiency and durable antibacterial properties for air filtration

HypothesisParticulate matter (PM) pollution and the coronavirus (COVID-19) pandemic have increased demand for protective masks. However, typical protective masks only intercept particles and produce peculiar odors if worn for extended periods owing to bacterial growth. Therefore, new protective materials with good filtration and antibacterial capabilities are required. ExperimentsIn this study, we prepared multi-scale polyvinylidene fluoride (PVDF) nanofibrous membranes for efficient filtration and durable antibacterial properties via N-halamine modification. FindingsThe N-halamine-modified nanofibrous membrane (PVDF-PAA-TMP-Cl) had sufficient active chlorine content (800 ppm), and the tensile stress and strain were improved compared with the original membrane, from 6.282 to 9.435 MPa and from 51.3 % to 56.4 %, respectively. To further improve the interception efficiency, ultrafine nanofibers (20–35 nm) were spun on PVDF-PAA-TMP-Cl nanofibrous membranes, and multi-scale PVDF-PAA-TMP-Cl nanofibrous membranes were prepared. These membranes exhibited good PM0.3 interception (99.93 %), low air resistance (79 Pa), promising long-term PM2.5 purification ability, and high bactericidal efficiency (>98 %). After ten chlorination cycles, the antibacterial efficiency against Escherichia coli and Staphylococcus aureus exceeded 90 %; hence, the material demonstrated highly efficient filtration and repeatable antibacterial properties. The results of this study have implications for the development of air and water filtration systems and multi-functional protective materials.

STUDY OF THE ANTIMICROBIAL ACTION OF «SANATION +» FOR THE PREVENTION AND TREATMENT OF ACUTE RESPIRATORY DISEASES

State of the problem. Given the extreme threat of the Covid-19 pandemic in Ukraine to combat it, it is now important to develop and use effective antimicrobials, including disinfectants to disrupt the transmission mechanisms of the pathogen. Promising for use are the means obtained by electrolysis. The aim of the work. The study was to determine the specific activity and safety of «Sanation+», the effectiveness of disinfection of the mucous membranes of the upper respiratory tract of volunteers and evaluate the effectiveness of the tool for the treatment of patients with Сovid-19 and for the prevention of respiratory diseases. Materials and methods. The study used a medical device «Sanation+», which contains hydrochloric acid, highly active oxygen compounds of chlorine, free radicals of chlorine and oxygen, NaCl (mass concentration of active chlorine – 0.035%). The antimicrobial action of the product according to the Order of the Ministry of Health of Ukraine N 2024, dated September 3, 2020. To study the effectiveness of decontamination of the upper respiratory tract of volunteers with the «Sanation+» used devices for the formation of aerosols: – nebulizer «Nano Mist Sprayer» (China), which sprays the drug with a volume of 1.25 - 1.45 cm3 for 60 seconds. The distance from the spray to the mucous membranes was 5 - 10 cm; – compressor inhaler, model CN-123 (Japan). Results. It was found that the tool «Sanation+» showed high virilicidel, bactericidal and yeastic activity under exposure for 30 and 60 sec. for Escherichia coli K12 NCTC 10538 lg R > 5.42, for Pseudomonas aeruginosa lg R > 5.37; for Staphylococcus aureus lg R > 5.34; for Candida albicans lg R > 4.31. Remediation + when used undiluted and exposed for 30 sec is an effective tool for disinfection from macro- and microviruses, as evidenced by the high logarithms of the reduction of bacteriophages: T2 – > 5.08 lg, MS2 – > 5.12 lg, indicating the virucidal action of the tool against enveloped and non-enveloped viruses. As a result of the application of «Sanation+» through the nebulizer «Nano Mist Sprayer» there was a significant reduction in the number of microorganisms on the mucosal surface of nasal volunteers: after 5 min the drug decreased by 4.22 lg, on the throat mucosa – by 4.14 lg. The use of the drug through an inhaler helped to reduce the number of microorganisms on the surface of the mucous membranes of both the nose and throat. The most effective duration of action is 5 min (reduction factor: for the nasal mucosa RF = 4.23, for the throat mucosa RF = 4.78). Conclusions. High efficiency of means for rehabilitation of respiratory tracts «Sanation+», for application in complex therapy at treatment of a coronavirus disease at 55 patients is established. The use of «Sanation+» for the prevention of Covid-19 among health care workers in medical institutions of the disease was not detected. Key words: remedy «Sanation+», bactericidal, virucidal, volunteers, patients, Сovid-19.