Chlorine Solution Research Articles

Chemical aspects of manganese removal from mine water at copper–sulfide deposits

The key mechanisms of selective recovery of manganese ions from mine water by combination of chemical and electrochemical methods are studied. The authors present efficient parameters of oxidation deposition of ions Mn2+ in electrolysis solutions of active chlorine forms generated in chloride-containing solutions under electric treatment and subsequent removal of dispersed phase manganese from the solutions. The mechanism for generation of dispersed phase manganese by electric treatment of acid mine water at copper–sulfide deposits is offered.

Análise da concentração e do ph de diferentes marcas comerciais e em diferentes tempos do hipoclorito de sódio

The purpose of this study, in vitro, was to evaluate the concentration of free chlorine and pH Sodium hypochlorite solutions at different concentrations and time periods; and verify that they were within the specified by the manufacturer. Four samples Sodium hypochlorite solutions at different concentrations (4 to 6%, 2.5%, 5 to 7% and 2 to 2.5%) and presentations (commercial - Soda Clorada™, Uraby™, e Barra™, and manipulated - ISOFAR) were maintained without light and at roam temperature. The measurements took place in the opening of the bottles and at intervals of 7, 14, 21 and 28 days. The analysis of free chlorine content was performed by the method of iodometry and pH by a digital pH meter. It was found that the experimental time the marks ISOFAR and Uraby™, were to chlorine concentration lower than reported by the manufacturer and brands Soda Clorada™, and Barra™, above. Regarding the pH, the solutions tested showed a slight increase in values, followed by decrease. lt can be concluded that the solutions were not according to the specified concentration by the manufacturer; and there was a decrease of chlorine concentration and the pH ranged around 11 to 12.

Novel high-flux thin film composite nanofiltration membranes fabricated by the NaClO pre-oxidation of the mixed diamine monomers of PIP and BHTTM in the aqueous phase solution

Novel high-flux thin film composite (TFC) nanofiltration (NF) membranes were fabricated by the sodium hypochlorite (NaClO) pre-oxidation of the mixed diamine monomers of piperazine (PIP) and 2,2′-bis(1-hydroxyl-1-trifluoromethyl-2,2,2-triflutoethyl)-4,4′-methylenedianiline (BHTTM) in the aqueous phase solution, and via interfacial polymerization (IP) with trimesoyl chloride (TMC) on the polysulfone (PSF) ultrafiltration (UF) membrane. The chemical change of the pre-oxidation aqueous phase solution was characterized by LC-MS. By optimizing the NaClO and NaOH content in the aqueous phase solution, the pure water flux was improved greatly and the salt rejection kept on a high level (>90%). The properties of NF membranes were characterized by XPS, SEM, AFM and contact angle. Through the NaClO pre-oxidation of the mixed diamine monomers of PIP and BHTTM in the aqueous phase solution, the active layer of NF membrane became thinner and the pore size of NF membrane was enlarged. Besides, after oxidation treatment by 3000ppm active chlorine solution for 1h, the NF membrane exhibited pure water flux (PWF) with 161 (LMH) and Na2SO4 rejection of 92.1% under 0.6MPa. The molecular weight cut-off (MWCO) of the NF membrane was greater than 500, which was calculated from the carbohydrates rejection. The good performance and the satisfactory stability of the novel high-flux NF membrane demonstrated its good potential in the practical application.

Decontamination Efficacy of Neutral and Acidic Electrolyzed Water in Fresh-Cut Salad Washing

The possibility of washing fresh-cut vegetables with neutral (NEW) and acidic (AEW) electrolyzed water instead of highly chlorinated solution was investigated. The decontamination efficacy was tested in vitro against Pseudomonas fluorescens, which is a typical inhabitant of leafy vegetables. The antibacterial efficacy of NEW and AEW was highly dependent on pH solution. NEW and AEW that were adjusted to a pH analogous to that of salad (6.5) completely inactivate P. fluorescens at 30 mg/L free chlorine concentration. The same result was achieved by sodium hypochlorite aqueous solution at a much higher free chlorine concentration (150 mg/L). NEW and AEW at 30 mg/L free chlorine concentration also reduced total mesophilic count, Pseudomonas spp. and total coliforms of salad by circa 1 log cycle. Microbial loads of wastewater deriving from salad washing resulted below the detection limit. Practical Applications Electrolyzed water can be exploited as a sanitizing washing agent in the fresh-cut industry allowing to replace conventional chlorination of washing water with highly concentrated NaOCl. Thus, it would be possible to guarantee an analogous decontamination efficacy and decrease the overall presence of potentially toxic chlorine compounds in wastewater. This would contribute to meet the global requirement of reducing the water footprint of industrial washing and reduce the use of harmful disinfection solutions.

Providing nursing care to Ebola virus disease patients: China Ebola Treatment Unit experience.

Providing nursing care to Ebola virus disease patients: China Ebola Treatment Unit experience.

Effect of Pretreatment and Modified Atmosphere Packaging on Quality of dry Coleslaw mix

The aim of the study was to determine the effect of soaking in chlorinated water (100 ppm chlorine) or mild thermal treatment in water (55°C; 3 min) and modified atmosphere packaging on the quality and shelf life of dry coleslaw stored for 12 days at 4°C. Samples were packaged in low‐barrier film in modified atmosphere containing: 5/10/85, 20/25/55, 50/30/20, 70/30/0 %O2/% CO2/% N2, and air atmosphere. In‐pack gas levels, sensory quality, microbial counts and cell permeability were determined.In comparison to non‐processed coleslaw, pretreatment of coleslaw, both consisting in soaking in chlorine solution and a mild thermal processing, resulted in a reduction by approx. 1 logarithmic cycle for counts of psychrophilic and lactic acid bacteria as well as mesophilic and psychrophilic yeasts, by 1 and 1.7 logarithmic cycle for coliform bacteria and by 2 up to 3 logarithmic cycles for Pseudomonas bacteria. Modified atmosphere (irrespective of its composition) used in product packaging was found to have no effect on the count of mesophilic bacteria. An elevated content of carbon dioxide in modified atmosphere (10, 25 or 30%) inhibited growth of psychrophilic bacteria and Pseudomonas bacteria up to 6 days of storage. In the case of coliform bacteria growth inhibition during storage was recorded both in the samples packaged in air atmosphere and in the atmosphere of 50/30/20 and 70/30/0 %O2/% CO2/% N2. In samples packaged in the atmosphere of 70% O2 and 30% CO2 after 12 days the greatest cell permeability was recorded, which was connected with a deterioration of their microbiological quality. Copyright © 2015 John Wiley & Sons, Ltd.

Novel Wash Aid T-128 Enhances the Efficacy of Chlorine against Salmonella on Tomatoes

A novel wash aid, T-128, was evaluated for its capacity to enhance the efficacy of chlorine solution for tomato washing against Salmonella enterica in the presence of high organic load. Incremental amount of tomato juice was added to chlorinated wash solutions to simulate free chlorine depletion during tomato washing operations. Cells of S. enterica were either directly inoculated into the wash solutions or onto the tomatoes that are washed in chlorinated solutions with or without T-128. Salmonella cells survived in the wash solution, in the stem-scar areas, and in the internal tissues of tomatoes were enumerated. Application of T-128 significantlyreduced the survival of Salmonella in chlorinated water when free chlorine approached depletion. It also resulted in a significantly higher reduction of S. entericapopulation on stem scars compared to the control. When inoculated and non-inoculated tomatoes were washed together, cross contamination by Salmonella cells to the non-inoculated tomatoes were reduced in the presence of T-128. The application of T-128 also significantly improved the chlorine efficacy against Salmonella internalization when chlorine concentration was near depletion. These results indicated that T-128 has the potential to improve chlorine efficacy against pathogen survival, cross-contamination and internalization in the wash solution when chlorine neared depletion, thus improve the safety margin of the process control.

A case of a chlorine inhalation injury in an Ebola treatment unit

We present a 26-year-old male British military nurse, deployed to Sierra Leone to treat patients with Ebola virus disease at the military-run Kerry Town Ebola Treatment Unit. Following exposure to...

Interaction of gold-bearing sulfides with modified chlorine solutions

The article reports tests on studying mechanism of interaction between modified chlorine solutions and gold-bearing sulfides. The change in texture, structural properties and elemental composition of sulfides after electrochemical treatment is analyzed. The authors indicate basic negative factors reducing dissolution velocity of sulfides.

Intensive care unit environmental surfaces are contaminated by multidrug-resistant bacteria in biofilms: combined results of conventional culture, pyrosequencing, scanning electron microscopy, and confocal laser microscopy

Hospital-associated infections cause considerable morbidity and mortality, and are expensive to treat. Organisms causing these infections can be sourced from the inanimate environment around a patient. Could the difficulty in eradicating these organisms from the environment be because they reside in dry surface biofilms? The intensive care unit (ICU) of a tertiary referral hospital was decommissioned and the opportunity to destructively sample clinical surfaces was taken in order to investigate whether multidrug-resistant organisms (MDROs) had survived the decommissioning process and whether they were present in biofilms. The ICU had two 'terminal cleans' with 500 ppm free chlorine solution; items from bedding, surrounds, and furnishings were then sampled with cutting implements. Sections were sonicated in tryptone soya broth and inoculated on to chromogenic plates to demonstrate MDROs, which were confirmed with the Vitek2 system. Genomic DNA was extracted directly from ICU samples, and subjected to polymerase chain reaction (PCR) for femA to detect Staphylococcus aureus and the microbiome by bacterial tag-encoded FLX amplicon pyrosequencing. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were performed on environmental samples. Multidrug-resistant bacteria were cultured from 52% (23/44) of samples cultured. S. aureus PCR was positive in 50%. Biofilm was demonstrated in 93% (41/44) of samples by CLSM and/or SEM. Pyrosequencing demonstrated that the biofilms were polymicrobial and contained species that had multidrug-resistant strains. Dry surface biofilms containing MDROs are found on ICU surfaces despite terminal cleaning with chlorine solution. How these arise and how they might be removed requires further study.

Formation of trichloromethane in chlorinated water and fresh-cut produce and as a result of reaction with citric acid

Chlorine (sodium hypochlorite) is commonly used by the fresh produce industry in the U.S. to sanitize wash water, fresh and fresh-cut fruits and vegetables. However, possible formation of harmful chlorine by-products is a concern. The objectives of this study were to compare chlorine and chlorine dioxide in trichloromethane formation, determine trichloromethane levels in chlorinated wash water, cut-lettuce and diced onions, and evaluate the reaction of chlorine with citric acid, a chemical often used to adjust pH of chlorine solution. Results showed that little trichloromethane (≤3μgL−1) was produced from chlorine dioxide solution even at concentrations up to 200mgL−1 compared with the trichloromethane level (∼40μgL−1) in solutions of chlorine mixed with lettuce extract. The formation of trichloromethane in 1L of 100mgL−1 chlorine wash water increased from 155 to 284μgL−1 after repeated use of the wash water to wash six batches of 100g cut lettuce. Levels of trichloromethane in the washed cut lettuce were in the range of 14–22μgkg−1, and were reduced to less than 8μgkg−1 after being rinsed with water. Chlorine solution used to wash diced onions produced much less trichloromethane (32μgL−1) compared with that for washing cut lettuce despite higher chemical oxygen demand and turbidity in the wash water. Citric acid reacted with chlorine and produced trichloromethane. Over 1000μgL−1 trichloromethane was produced after 30min reaction with chlorine at 22°C, while less than 35μgL−1 trichloromethane was produced when Na-phosphate was used to adjust pH of chlorine. The amount of trichloromethane increased with reaction time and concentration of citrate. Our results demonstrated that formation of trichloromethane in wash water depended on type of cut-vegetables, and citric acid contributed to a significant amount of trichloromethane formation.

Skin side effects of chlorine solutions used for hand hygiene: a systematic review

Chlorine solutions (CS), mostly containing sodium hypochlorite (SH), have been widely used for hand hygiene (HH) in the West African countries affected by the Ebola outbreak due to unavailability of alcohol-based handrub solutions and soap, easiness of use and “fear” factors leading to (false) sense of safety given by using an easily available disinfectant. However, no HH guidelines recommend the use of CS and concerns have been raised about skin tolerability among users.

Efficacy of chlorine solutions used for hand hygiene and gloves disinfection in Ebola settings: a systematic review

Chlorine solutions (CS) have been widely used for hand hygiene (HH) in the West African countries affected by the current Ebola outbreak. However, no HH guidelines recommend the use of CS for HH practices.

Physicochemical, microbial and sensory quality of fresh-cut red beetroots in relation to sanization method and storage duration

Effects of sanitization and storage on fresh-cut beetroots ( Beta vulgaris L.) were evaluated following sanitation – peeling - cutting (SPC), peeling – sanitation – cutting (PSC) and peeling – cutting – sanitation (PCS) methods with (Cl), or without (TW), 100 ppm chlorine solution, then packaged in polyethylene bag and stored at 5°C for up to 14 days. Chroma values of fresh-cut beetroots significantly declined whereas whiteness index and titratable acidity values increased, however, texture and total soluble solid contents showed no significant variation. Betalain contents decreased gradually and total phenol content showed inconsistence trend. PCS-Cl treated samples accounted for higher betalains decline and received lower visual quality scores despite its lower total aerobic bacterial count. Minimum microbial population was observed in PSC-Cl methods along with higher levels of betalain contents. Considering pigment retention, microbial and visual qualities, beetroots sanitized with chlorine water following PSC method was the best processing way for fresh-cut beetroots and therefore, PSC-Cl treatment could commercially be used for processing of fresh-cut beetroots.

Effectiveness of chlorine dispensers in emergencies: case study results from Haiti, Sierra Leone, Democratic Republic of Congo, and Senegal.

Dispensers are a source-based water quality intervention with promising uptake results in development contexts. Dispenser programs include a tank of chlorine with a dosing valve that is installed next to a water source, a local Promoter who conducts community education and refills the Dispenser, and chlorine refills. In collaboration with response organizations, we assessed the effectiveness of Dispensers in four emergency situations. In the three initial and four sustained response phase evaluations, 70 Dispenser sites were visited, 2057 household surveys were conducted, and 1676 water samples were analyzed. Across the evaluations, reported Dispenser use ranged from 9 to 97%, confirmed Dispenser use (as measured by free chlorine residual) ranged from 5 to 87%, and effective use (as measured by improvement in household water quality to meet international standards) ranged from 0 to 81%. More effective Dispenser interventions installed Dispensers at point-sources, maintained a high-quality chlorine solution manufacturing and distribution chain, maintained Dispenser hardware, integrated Dispensers projects within larger water programs, remunerated Promoters, had experienced project staff, worked with local partners to implement the project, conducted ongoing monitoring, and had a project sustainability plan. Our results indicate that Dispensers can be, but are not always, an appropriate strategy to reduce the risk of waterborne diseases in emergencies.

Analysis of a blast due to inadvertant mixing of ammonium sulfate and sodium hyplochlorite

Ammonium sulfate and sodium hypochlorite are common industrial chemicals, often used together in water treatment. The consequences of mixing hypochlorite (chlorine) solution with ammonia solutions are well understood within the chlorine industry; detonable chloramines are produced. This knowledge is not well known in other industries; fortunately, few locations have both chemicals on site. These products were inadvertently mixed, resulting in an explosion, at a water treatment facility in Kitchener, Ontario on April 2, 2014. The chemistry of the incident is presented and discussed. Facilities that handle both chemicals, such as the water treatment industry need to have heightened sense of understanding of this particular reactive chemical hazard. © 2015 American Institute of Chemical Engineers Process Saf Prog 35: 92–95, 2016

Redox-Induced Reversible Uptake–Release of Cations in Porous Ionic Crystals Based on Polyoxometalate: Cooperative Migration of Electrons with Alkali Metal Ions

Redox-active porous ionic crystals based on polyoxometalates (POM) were synthesized. By treating the crystal with an aqueous solution of ascorbic acid (reducing reagent) and KCl, one-electron reduction of POM proceeded followed by simultaneous uptake of K+. Interestingly, the reduction did not proceed without KCl, and the molecular size of ascorbic acid was too large to enter the porous crystal lattice. The time courses of reduction and K+ uptake were monitored by UV–vis spectroscopy and atomic absorption spectrometry (AAS), respectively. Both profiles could be reproduced by the linear driving force (LDF) model with similar rate constants. The reduced crystal could be oxidized with aqueous chlorine solution followed by the release of K+, and the redox cycles were reversible. The water sorption properties of the crystals could be controlled by the types of alkali metal ions incorporated. The Cs+ uptake and the simultaneous reduction of the crystal proceeded much faster than in the case of K+, which is in line with the trends in the Gibbs energies of hydration of alkali metal ions. Complete selectivity to Cs+ was observed in the uptake of ions from an aqueous binary mixture of Cs+ and Na+. All these results suggest the cooperative migration of electrons with alkali metal ions and the redox induced ion-exchange in porous ionic crystals based on POM.

Fate of Salmonella enterica in a Mixed Ingredient Salad Containing Lettuce, Cheddar Cheese, and Cooked Chicken Meat

Food service and retail sectors offer consumers a variety of mixed ingredient salads that contain fresh-cut vegetables and other ingredients such as fruits, nuts, cereals, dairy products, cooked seafood, cooked meat, cured meats, or dairy products obtained from external suppliers. Little is known about the behavior of enteric bacterial pathogens in mixed ingredient salads. A model system was developed to examine the fate of Salmonella enterica (inoculum consisting of S. enterica serovars Agona, Typhimurium, Enteritidis, Brandenberg, and Kentucky) on the surface of romaine lettuce tissues incubated alone and in direct contact with Cheddar cheese or cooked chicken. S. enterica survived but did not grow on lettuce tissues incubated alone or in contact with Cheddar cheese for 6 days at either 6 or 14°C. In contrast, populations increased from 2.01 ± 0.22 to 9.26 ± 0.22 CFU/cm(2) when lettuce washed in water was incubated in contact with cooked chicken at 14°C. Populations on lettuce leaves were reduced to 1.28 ± 0.14 CFU/cm(2) by washing with a chlorine solution (70 ppm of free chlorine) but increased to 8.45 ± 0.22 CFU/cm(2) after 6 days at 14°C. Experimentation with a commercial product in which one third of the fresh-cut romaine lettuce was replaced with inoculated lettuce revealed that S. enterica populations increased by 4 log CFU/g during storage for 3 days at 14°C. These findings indicate that rapid growth of bacterial enteric pathogens may occur in mixed ingredient salads; therefore, strict temperature control during the manufacture, distribution, handling, and storage of these products is critical.

A novel microfluidic mixer-based approach for determining inactivation kinetics of Escherichia coli O157:H7 in chlorine solutions

Determination of the minimum free chlorine concentration needed to prevent pathogen survival/cross-contamination during produce washing is essential for the development of science-based food safety regulations and practices. Although the trend of chlorine concentration-contact time on pathogen inactivation is generally understood, specific information on chlorine and the kinetics of pathogen inactivation at less than 1.00 s is urgently needed by the produce processing industry. However, conventional approaches to obtain this critical data have been unable to adequately measure very rapid responses. This paper reports our development, fabrication, and test of a novel microfluidic device, and its application to obtain the necessary data on pathogen inactivation by free chlorine in produce wash solution in times as short as 0.10 s. A novel microfluidic mixer with the capability to accurately determine the reaction time and control the chlorine concentration was designed with three inlets for bacterial, chlorine and dechlorinating solutions, and one outlet for effluent collection. The master mold was fabricated on a silicon wafer with microchannels via photopolymerization. Polydimethylsiloxane replicas with patterned microchannels were prototyped via soft lithography. The replicas were further assembled into the micromixer on glass via O2 plasma treatment, and the inlets were connected to a syringe pump for solution delivery. To determine the kinetics of free chlorine on pathogen inactivation, chlorine solutions of varying concentrations were first pumped into the micromixer, together with the addition of bacterial suspension of Escherichia coli O157:H7 through a separate inlet. This was followed by injection of dechlorinating solution to stop the chlorine-pathogen reaction. The effluent was collected and the surviving bacteria cells were enumerated using a modified ‘Most Probable Number’ method. Free chlorine concentration was determined using a standard colorimetric method. The contact time was experimentally set by adjusting the solution flow rate, and was estimated by computational fluid dynamics modeling. Results showed that 1) pathogen inactivation was significantly affected by free chlorine concentration (P < 0.0001) and subsecond reaction time (P < 0.0001) and their interactions (P < 0.0001); and 2) the current industry practice of using 1.0 mg/L free chlorine will require more than 1.00 s total contact to achieve a 5-log10 reduction in an E. coli O157:H7 population, whereas a 10.0 mg/L free chlorine solution will achieve 5-log10 reduction in as little as 0.25 s. Information obtained from this study will provide critical insight on kinetics of bacterial inactivation for a broad range of sanitizers and produce wash operational conditions, thus facilitating the development and implementation of science-based food safety regulations and practices for improving food safety.

Scrapie: a particularly persistent pathogen

RESISTANT prions in the environment have been the sword of Damocles for scrapie control and eradication. Attempts to establish which physical and chemical agents could be applied to inactivate or...