Chlorine Gas Research Articles

Double-Shell Co3O4 with Rich Surface Octahedron Oxygen Vacancies for High-Selectivity Electrocatalytic Chlorine Evolution.

The development of non-noble-metal-based chlorine evolution reaction (CER) catalysts with excellent activity, kinetics, and selectivity is urgently needed but still remains a major challenge. In this study, a morphology self-evolving and surface octahedron oxygen-vacancy-generating strategy is applied at double-shell nanospheres to obtain the target hierarchical double-shell Co3O4 nanospheres with abundant surface oxygen vacancies (DS-Co3O4-OVs). The DS-Co3O4-OVs display an overpotential of only 52 mV to reach a current density of 10 mA cm-2 in which an excellent chlorine selectivity of 98.9-99.9% is attained, which is better than that of the commercial RuO2/IrO2. Furthermore, density functional theory calculations demonstrate that the involved oxygen vacancies can not only limit the lattice oxygen mechanism of the oxygen evolution reaction process but also significantly improve the kinetics of the Volmer step to enhance the CER performance. Meanwhile, the unique hierarchical double-shell nanospheres can enhance the mass feeding and promote the rate-determining step of the Krishtalik step chlorine gas desorption reaction for enhanced kinetics. The self-evolution of non-noble catalysts with surface octahedron vacancies and the related exploration of the CER mechanism may provide a novel design idea for CER catalysts.

Using Artificial Neural Networks to Predict Operational Parameters of a Drinking Water Treatment Plant (DWTP)

The scope of the present study is the estimation of key operational parameters of a drinking water treatment plant (DWTP), particularly the dosages of treatment chemicals, using artificial neural networks (ANNs) based on measurable in situ data. The case study consists of the Aposelemis DWTP, where the plant operator had an estimation of the ANN output parameters for the required dosages of water treatment chemicals based on observed water quality and other operational parameters at the time. The estimated DWTP main operational parameters included residual ozone (O3) and dosages of the chemicals used: anionic polyelectrolyte (ANPE), poly-aluminum chloride hydroxide sulfate (PACl), and chlorine gas (Cl2(g)). Daily measurable results of water sample analysis and recordings from the DWTP Supervisory Control and Data Acquisition System (SCADA), covering a period of 38 months, were used as input parameters for the artificial neural network (1188 values for each of the 14 measurable parameters). These input parameters included: raw water supply (Q), raw water turbidity (T1), treated water turbidity (T2), treated water residual free chlorine (Cl2), treated water concentration of residual aluminum (Al), filtration bed inlet water turbidity (T3), daily difference in water height in reservoir (∆H), raw water pH (pH1), treated water pH (pH2), and daily consumption of DWTP electricity (El). Output/target parameters were: residual O3 after ozonation (O3), anionic polyelectrolyte (ANPE), poly-aluminum chloride hydroxide sulfate (PACl), and chlorine gas supply (Cl2(g)). A total of 304 different ANN models were tested, based on the best test performance (tperf) indicator. The one with the optimum performance indicator was selected. The scenario finally chosen was the one with 100 neural networks, 100 nodes, 42 hidden nodes, 10 inputs, and 4 outputs. This ANN model achieved excellent simulation results based on the best testing performance indicator, which suggests that ANNs are potentially useful tools for the prediction of a DWTP’s main operational parameters. Further research could explore the prediction of water chemicals used in a DWTP by using ANNs with a smaller number of operational parameters to ensure greater flexibility, without prohibitively reducing the reliability of the prediction model. This could prove useful in cases with a much higher sample size, given the data-demanding nature of ANNs.

Optical absorption spectrum reveals gaseous chlorine in anti-resonant hollow core fibers

We have observed unexpected spectral attenuation of ultraviolet light in freshly drawn hollow core optical fibers. When the fiber ends are left open to atmosphere, this loss feature dissipates over time. The loss matches the absorption spectrum of gaseous (molecular) chlorine and, given enough time, the transmission spectrum of the fiber recovers to that expected from the morphological structure of the fiber. Our measurements indicate an initial chlorine concentration of 0.45 µmol/cm3 in the hollow core, equivalent to 1.1 mol% Cl2 at atmospheric pressure.

Direct electrosynthesis and separation of ammonia and chlorine from waste streams via a stacked membrane-free electrolyzer

Electrosynthesis, a viable path to decarbonize the chemical industry, has been harnessed to generate valuable chemicals under ambient conditions. Here, we present a membrane-free flow electrolyzer for paired electrocatalytic upcycling of nitrate (NO3−) and chloride (Cl−) to ammonia (NH3) and chlorine (Cl2) gases by utilizing waste streams as substitutes for traditional electrolytes. The electrolyzer concurrently couples electrosynthesis and gaseous-product separation, which minimizes the undesired redox reaction between NH3 and Cl2 and thus prevents products loss. Using a three-stacked-modules electrolyzer system, we efficiently processed a reverse osmosis retentate waste stream. This yielded high concentrations of (NH4)2SO4 (83.8 mM) and NaClO (243.4 mM) at an electrical cost of 7.1 kWh per kilogram of solid products, while residual NH3/NH4+ (0.3 mM), NO2− (0.2 mM), and Cl2/HClO/ClO− (0.1 mM) pollutants in the waste stream could meet the wastewater discharge regulations for nitrogen- and chlorine-species. This study underscores the value of pairing appropriate half-reactions, utilizing waste streams to replace traditional electrolytes, and merging product synthesis with separation to refine electrosynthesis platforms.

Hydrogen production from ZnCl2 salt: Application of chlor-alkali method

This experimental study investigates the efficiency of hydrogen production from an aqueous ZnCl2 solution using an electrochemical method within a chlor-alkali reactor. A laboratory-scale reactor with separate anode and cathode compartments was constructed for this purpose. The compartments are separated by a Nafion 212 membrane, which prevents the mixing of the anolyte and catholyte solutions while allowing the passage of positive ions (Zn+). Each compartment is equipped with five carbon rod electrodes. The anode chamber is fed with an aqueous ZnCl2 solution, while the cathode chamber is supplied with pure water. The experiments were conducted with a constant electrolyte transfer rate of 0.3g/s into the reactor, at three different cell voltages (5.0, 7.5, and 10.0V) and two different cell temperatures (20 °C and 45 °C). Due to the small reactor dimensions and the dilution effect caused by adding pure water to the cathode compartment which decreases electrolyte density and adversely affects the current a noticeable reduction in hydrogen gas production was observed. Furthermore, the ZnCl2 electrolyte mass flow rate did not significantly impact the current or the generation of hydrogen and chlorine gases. Consequently, no changes were made to the mass flow rate of pure water or the electrolyte. The presence of active chlorine gas was found to cause the erosion of the carbon rod electrodes in the anode chamber. As a result, the amount of chlorine gas produced in the anode chamber is significantly lower than the hydrogen gas produced in the cathode chamber. At a cell temperature of 20 °C, a mass flow rate of 0.3 g/s, and a cell voltage of 5 V with ZnCl2 aqueous solution, the minimum hydrogen production rate is 0.625 mL/min. In contrast, at a cell temperature of 45 °C, a mass flow rate of 0.3 g/s, and a cell voltage of 10 V, the maximum hydrogen production rate is 4.97 mL/min.

Synergistic effects and comprehensive analysis of interaction during infrared co-pyrolysis of furfural residues and PVC

Infrared co-pyrolysis was employed to convert waste into valuable resource due to the increasing production of plastic waste. In this study, support vector machine (SVM) accurately predicted PVC and furfural residues thermal behavior. The results showed high accuracy (R2 > 0.95) after the SVM model was trained and validated. Furthermore, this research performed an in-depth characterized of the co-pyrolysis process using various analytical techniques, indicting TG-FTIR-GC/MS, XPS, simulated distillation, and GC/MS. As the temperatures and heating rates increased, the pyrolysis oil yield increased at first and then declined, reaching a maximum of 37.7 % at 600 °C and 10 °C/s. Notably, aromatic content was relatively high, comparing with other components, whereas the chlorinated content remained relatively low, all below 6.5 %, indicating the pyrolysis oil quality had effectively improved. According to the results of XPS, there was a significant 64.11 % increase in inorganic chlorination, which suggested the effective reduction in gaseous chlorine emission and achieving chlorine immobilization.

Development of a ReaxFF Reactive Force Field for Pt/Cl Systems with Application to Platinum Metal Etching with Chlorine and Hydrogen Chloride Gases.

In this study, we present the development of a ReaxFF Pt/Cl/H reactive force field designed to elucidate the etching process by Cl for Pt surfaces. The ReaxFF force field parameters were optimized based on a quantum mechanical training set, which included adsorption energies of Cl and dissociation of HCl on Pt(100) and Pt(111) surfaces, energy/volume relations of PtCl2 crystals, and Cl diffusion on Pt(100) and Pt(111) surfaces. The predictive capability of the force field was further established through molecular dynamics simulations, which investigated the interactions of Cl2 and HCl molecules with the (100) and (111) surfaces of c-Pt crystalline solid slabs. A comparative analysis revealed that the Pt (100) surface exhibited higher susceptibility to chlorination and etching, leading to a more dominant removal of surface Pt atoms, whereas the Pt (111) surface showed greater resistance to these processes. This resistance impeded the access of Cl atoms to the Pt surface, resulting in a slower formation of PtxCly molecules. The etching ratios between HCl and Cl2 were compared with experimental results, yielding satisfactory agreement. This indicates that the developed ReaxFF protocol serves as a valuable tool for studying atomistic-scale details of the etching process in platinum metal systems.

Quantitative assessment of chlorine gas inhalation injury based on endoscopic OCT and spectral encoded interferometric microscope imaging with deep learning.

Chlorine exposure can cause severe airway injuries. While the acute effects of chlorine inhalation are well-documented, the structural changes resulting from the post-acute, high-level chlorine exposure remain less understood. Airway sloughing is one of the standards for doctors to evaluate the lung function. Here, we report the application of a high-resolution swept-source optical coherence tomography system to investigate the progression of injury based on airway sloughing evaluation in a chlorine inhalation rabbit model. This system employs a 1.2mm diameter flexible fiberoptic endoscopic probe via an endotracheal tube to capture in vivo large airway anatomical changes before and as early as 30minafter acute chlorine exposure. We conducted an animal study using New Zealand white rabbits exposed to acute chlorine gas (800 ppm, 6min) during ventilation and monitored them using optical coherence tomography (OCT) for 6h. To measure the volume of airway sloughing induced by chlorine gas, we utilized deep learning for the segmentation task on OCT images. The results showed that the volume of chlorine induced epithelial sloughing on rabbit tracheal walls initially increased, peaked around 30min, and then decreased. Furthermore, we utilized a spectral encoded interferometric microscopy system to study ex vivo airway cilia beating dynamics based on Doppler shift, aiding in elucidating how chlorine gas affects cilia beating function. Cilia movability and beating frequency were decreased because of the epithelium damage. This quantitative approach has the potential to enhance the diagnosis and monitoring of injuries from toxic gas inhalation and to evaluate the efficacy of antidote treatments for these injuries.

Trends in chlorine and chloramine gas exposures reported to United States poison centers

Introduction Chlorine and chloramine gas inhalation can occur when household cleaners are mixed. The increased emphasis on disinfecting practices during the COVID-19 pandemic may have contributed to an increase in chlorine and chloramine gas exposures in the United States, which has not been studied. Methods In a retrospective review, reported data on chlorine and chloramine gas exposures in the National Poison Data System were collected from January 1, 2015, to December 31, 2022. Data included demographics and exposure details, including location, dose, formulation, co-exposures, treatments, and outcomes. Demographic analyses and descriptive statistics were conducted. Results During the study period, 85,104 total exposures to chlorine and chloramine gas were reported, consisting of 79,281 isolated exposures and 5,823 co-exposures. Total exposures increased by 61% from 8,385 in 2015 to 13,503 in 2022, with the largest increase of 38.3% occurring from 2019 to 2020. Total exposures remained increased through 2022 with no return to pre-pandemic levels. Most exposures occurred in “own residence” (n = 72,213, 84.9%), with a larger proportion of exposures occurring at home peri-pandemic versus pre-pandemic (88.4% versus 81.7%). One percent (n = 1,030) of exposures were admitted to a non-critical care unit, 0.73% (n = 619) were admitted to a critical care unit, and 0.03% (n = 26) resulted in death. Discussion The onset of the COVID-19 pandemic and increased emphasis on cleaning practices were likely contributing factors to the marked increase in exposures in 2020, which persisted through 2022. Cleaning practices that developed during the beginning of the pandemic likely persisted despite returning to more normal daily routines, which may explain the ongoing increase in reported exposures. Most reported exposures were unintentional, mild in symptomatology, and required the use of non-invasive therapies, if any. Conclusions Future efforts should focus on public education on the safe use of cleaning products to prevent exposure to toxic chlorine and chloramine gases.

Chemical Substance Exposure of Some Cleaning Workers in Korea: Focusing on Inhalation Exposure

This study aimed to prevent health damage caused by chemical exposure among cleaning workers who use cleaning agents and disinfectants in facility management and kitchen areas. We analyzed 5 years of measurement data (2016–2020) for cleaning workers across various industries in Korea, and conducted an exposure survey and health risk assessment for the two most frequently measured substances (i.e., 2-butoxyethanol and sodium hydroxide) and representative substances generated by their combined use (i.e., chlorine and chloroform). The findings indicate that when chlorine was generated by mixing hypochlorite-based disinfectants (e.g., bleach) with acidic cleaners containing substances such as nitric, hydrochloric, or citric acid, the risk index for chlorine gas (based on the 95th percentile exposure values) was 5.65 in the facility management cleaning industry, exceeding the acceptable threshold of 1. Because of the high usage and exposure frequency of cleaning and disinfecting agents and the common practice of mixing multiple products to enhance cleaning efficacy, it is necessary to manage hazardous risk factors by providing education on appropriate working methods, supplying personal protective equipment, and installing ventilation systems for these workers. Further research on the health risk assessment of combined chemical use is needed.

Selective Extraction of Valuable and Critical Metals in Cassiterite Concentrate by Dry Chlorination, Part I: Thermodynamic and Modelling Perspective.

The chlorination of oxides of major concern in cassiterite concentrate with various chlorinating agents is investigated in light of their thermodynamic feasibilities to extract and recover their valuable metal components. Mechanisms responsible for the processes and their Gibbs free energy changes as a function of temperature to selectively separate and/or recover the metal(s) of interest and unwanted ones as their metallic chlorides are identified. Attention is given to gaseous (Cl2 and Cl2 + CO mixture) and solid (CaCl2 and MgCl2) chlorine sources, from which Cl2 + CO shows no reaction selectivity for any of the oxides but a feasible metal chloride formation for all. Chlorine gas (Cl2), on the other hand, could selectively form chlorides with metals of +2 oxidation state in their oxides, leaving those of high oxidation state unreacted. MgCl2, unlike CaCl2, is found capable of producing calcium, ferrous, and stannic chloride from their metallic oxides with enhanced reaction tendencies in the presence of silicon dioxide (SiO2). An overall study of the thermodynamic feasibility of all chlorine sources looked at alongside operational and environmental viabilities suitably suggests MgCl2 for a selective extraction of the valuable metal components in a cassiterite concentrate, in which case, moderate temperatures seem promising.

Enhancing stability of copper-based catalysts by regulating of oxygen vacancy for resourcing HCl waste gas

The utilization of copper-based catalysts for converting by-product hydrogen chloride (HCl) into chlorine gas (Cl2) offers a promising method for efficient management of HCl waste gas. However, a significant challenge in this process lies in catalyst deactivation, primarily attributed to the loss of active component in the form of Cu-Cl. In this study, we synthesized a Cu2.4CeV0.5Ox catalyst that exhibited remarkable performance, achieving a space-time yield of 2.26 g Cl2/gcat*h with stable conversion efficiency at approximately 83 % maintained over 600 h. This level of stability represents a substantial improvement compared to previous studies of copper-based catalysts. In-situ DRFITS combined with ToF-SIMS confirms the reduction evolution of metal-Cl bonds. Additionally, ab-initio calculations elucidated that the rate-limiting step involves oxygen vacancy replenishment by O2 rather than Cl over CeO2 and CeVO4, thereby inhibiting Cu-Cl bond formation. This study introduces a novel approach for efficienct treatment of HCl waste gas, paving the way for its potential industrial application.

Potential environmental impact of the chlorine-containing disinfectants usage during the COVID-19

Chlorine radicals (Cl) play a crucial role in atmospheric chemistry. The COVID-19 (coronavirus disease 2019) pandemic significantly increased the use of chlorine-containing disinfectants in China, leading to enhanced emissions of chlorine gas (Cl2) and hypochlorous acid (HOCl). In this study, we use the Community Multiscale Air Quality (CMAQ) model with updated chlorine chemistry to evaluate the potential air quality impact of chlorine emissions from disinfectant usage during February 2020, a month with a large outbreak of COVID-19 in mainland China. Results indicate that during the pandemic, there was a sharp increase of reactive chlorine emissions, with Cl2 and HOCl emissions reaching 773.9 t and 5913.1 t, making 3 times increase. The emissions of chlorine enhanced atmospheric oxidation capacity (AOC) through the oxidation of VOC by Cl and OH, with the average enhancement in Shanghai, Beijing and Wuhan areas reaching 4.6% ± 1.8%, 10.3% ± 6.6% and 7.4% ± 4.6%, respectively. Consequently, the use of chlorine-containing disinfectants may have contributed to observed increases in the monthly average of the maximum daily 8-h average ozone (MDA8 O3) and fine particulate matter (PM2.5) concentrations by up to 1.5 ppbv (5%) and 1.7 μg/m3 (1%), respectively. Especially, the maximum hourly increase values of O3 and PM2.5 concentrations were 4.8 ppbv and 11.4 μg/m³, 2.5 ppbv and 4.5 μg/m³ in Beijing and Wuhan, respectively. These results indicate that chlorine emissions from the widespread use of disinfectants have had a significant impact on air quality in certain regions (Beijing and Wuhan) and during specific periods (9:00∼12:00).

The plausibility and ideal design of electrochemical disinfection for drinking water in hospital susceptible to Legionella and E. coli contamination, compared to traditional methods

Legionella and Escherichia coli (E. coli), bacteria lethal to humans, are widespread in drinking water. Traditional disinfection methods using chlorine gas, temperature control, and ultraviolet are widely applied today but have several drawbacks. In contrast, the electrochemical disinfection methods could address the problems. This study reviews the literature on electrochemical disinfection and compares traditional disinfection methods with electrochemical ones under evaluation of cost, E. coli contamination efficiency, and effect. Results show that titanium meshed electrodes are the most cost-efficient compared to more effective electrodes with significantly higher production costs. The application of the proposed electrochemical disinfection device gains a financial advantage over traditional methods, suggesting a promising future for the disinfection method. Meanwhile, investigations on the electrocoagulation method aim to disinfect the water to the drinking water level. Results show that the combination of electrocoagulation and the titanium meshed electrode device proves to have a better disinfection effect than individual methods and a lower cost than traditional methods. This research provides insight into the properties of biofilms, traditional disinfection methods, and different electrochemical disinfection methods. After reviewing the literature and evaluating various factors, we offer an ideal design for Legionella and E. coli-contaminated water disinfection devices with a promising future once applied.

Scaling up gaseous chlorine dioxide (ClO2) treatment in the cold storage of fresh apples

Novel interventions are needed to mitigate microbial risks, like Listeria monocytogenes, before shipping fresh apples to retail markets. Batch gaseous chlorine dioxide (ClO2) in-storage treatments were conducted to assess the inactivation of Listeria innocua, reduction of spoilage microorganisms, and changes in quality. Gaseous ClO2 was generated using equal amounts of dry precursors inside the modified commercial refrigerator with 82 kg and 330 kg apples for pilot and semi-industrial scale experiments, respectively. A cocktail of L. innocua was spot inoculated on the calyx of fresh Fuji apples and treated with an initial ClO2 input of 1.2 g of each precursor/kg of produce at a pilot scale for 30 d and semi-industrial scale for 90 d. Headspace ClO2 concentrations, temperature, and relative humidity were measured during the batch treatments. Reductions of 1.4±0.2 and 1.2 log CFU/mL of Listeria innocua were achieved by pilot-scale and semi-industrial scale trials, respectively. The presence of spoilage microorganisms was not significantly (P>0.05) impacted, and apples displayed no signs of deterioration. This study confirms that ClO2 can significantly inhibit foodborne pathogens, such as Listeria, during prolonged cold storage and reduce the risk of contamination for apple growers.

Study of the influence of temperature and duration of chlorinating roasting on the extraction of gold from E-waste

In this work, based on experimental studies, the effect of roasting temperature and duration on the chlorination of gold from E-waste under low-temperature conditions was studied. It has been established that in the low-temperature range of 150-300 °C, the gold content in the residue shows a sharp decrease, reaching its minimum of 8 ppm at 250 °C. A further increase in temperature does not affect the gold content in the cinder. It has been shown that during chlorinating roasting above a temperature of 250 °C, side reactions should be expected to occur with the formation of additional phases representing chlorides of copper, iron and other elements. The results of SEM and XRD analyzes of the solid phase obtained after chlorinating roasting at a temperature of 250 °C and a roasting duration of 20 minutes showed the presence of copper and iron chlorides in them. Optimal technological parameters and modes of the process of chlorinating roasting of E-waste with gaseous chlorine have been established: temperature – 250 °С; roasting duration – 20 minutes; chlorine consumption is 1.5 times more than the stoichiometrically required amount (SRA) for gold chlorination. Under optimal roasting conditions, a high, up to ~97.6%, recovery of gold in the form of gold chloride (AuCl3) was achieved. The results of the experiments can be a basic basis and make it possible to conduct more representative experiments (scaling) in the future, taking into account the established optimal technological parameters. This will provide a chance to evaluate the possibility of extracting gold from E-waste of different types and compositions and to conduct further research on obtaining pure gold from the collected representative amount of gold sublimate AuCl3 by smelting.

Enabling direct seawater electrolysis by redox-inactive amphiphilic amines via chloride sequestration

Sustainable hydrogen production requires large amounts of treated freshwater and precious metals. Direct electrolysis of seawater without additional electrolytes can be a practical approach to address these limitations, however, it usually suffers from kinetically favored chlorine evolution reaction (CER), which is detrimental to an electrolysis system. We report that organocatalytic amphiphilic diamines play a crucial role in preventing the generation of chlorine gas. The feasibility of direct seawater electrolysis was demonstrated with pH-responsive organic amines, which can self-assemble under neutral and acidic conditions. Electrochemical analysis of our electrolysis in saline solutions revealed that (electro)chemical stability of amphiphilic diamines was responsible for preventing CER and hypochlorite formation. Our findings may have significant implications for the chemical industry and energy sectors as the world transitions towards renewable energy sources.

A Simple Organo-Electrocatalysis System for the Chlor-Related Industry.

Consuming a substantial quantum of energy (~165 TW h), the chlor-alkali industry garners considerable scholarly and industrial interest, with the anode reaction involving the oxidation of chloride ions being a paramount determinant of reaction rates. While the dimensionally stable anode (DSA) displays commendable catalytic activity and longevity, they rely on precious metals and exhibit a non-negligible side reaction in sodium hypochlorite (NaClO) production, underscoring the appeal of metal-free alternatives. However, the molecules and systems currently available are characterized by intricate complexity and are not amenable to large-scale production. Herein, we have successfully developed an economical and highly efficient molecular catalyst, demonstrating superior performance compared with the former organic molecules in the chloride ion oxidation process (COP) for the production of both chlorine gas (Cl2) and NaClO. The molecule of 2N only needs 92 mV to reach a current density of 1000 mA cm-2, with a small cost of only 0.002 $ g-1. Furthermore, we propose a novel mechanism underpinned by non-covalent interactions, serving as the foundation for an innovative approach to the design of efficient anodes for the COP.

A Simple Organo‐Electrocatalysis System for the Chlor‐Related Industry

AbstractConsuming a substantial quantum of energy (~165 TW h), the chlor‐alkali industry garners considerable scholarly and industrial interest, with the anode reaction involving the oxidation of chloride ions being a paramount determinant of reaction rates. While the dimensionally stable anode (DSA) displays commendable catalytic activity and longevity, they rely on precious metals and exhibit a non‐negligible side reaction in sodium hypochlorite (NaClO) production, underscoring the appeal of metal‐free alternatives. However, the molecules and systems currently available are characterized by intricate complexity and are not amenable to large‐scale production. Herein, we have successfully developed an economical and highly efficient molecular catalyst, demonstrating superior performance compared with the former organic molecules in the chloride ion oxidation process (COP) for the production of both chlorine gas (Cl2) and NaClO. The molecule of 2N only needs 92 mV to reach a current density of 1000 mA cm−2, with a small cost of only 0.002 $ g−1. Furthermore, we propose a novel mechanism underpinned by non‐covalent interactions, serving as the foundation for an innovative approach to the design of efficient anodes for the COP.

Evaluating the effectiveness of minimum chlorate technologies employed by manufacturers of skim milk powder from both microbiological quality and chemical residue perspectives

Dairy processors in the Republic of Ireland have adopted chlorine-free chemicals for cleaning and chlorine gas for water disinfection as a means of minimizing chlorate residue in dairy products. For these 'minimum chlorate technologies' to be satisfactory, they must be able to deliver product with acceptable levels of bacteria as well as minimum levels of chlorate and other chlorine based residues. To establish the effectiveness of these technologies, sampling was conducted across the skim milk powder (SMP) manufacturing chain in 3 separate milk processing sites. Across the 3 sites a total of 11 different batches of SMP were sampled in duplicate from the whole milk silo through the manufacturing process to the powder product; yielding a total of 137 samples. Samples were tested for chlorate, perchlorate and trichloromethane alongside a suite of microbiological plate count tests including total bacteria, thermophilic bacteria, thermoduric bacteria and both mesophilic and thermophilic spore-forming bacteria. Chlorate was detected at reportable levels (≥0.01 mg/kg) in 9 of 22 SMP samples analyzed; resulting in a mean chlorate concentration 0.0183 mg/kg. Bacteria were ubiquitous across all samples analyzed with spore-forming bacteria counts ranging from 1.30 to 2.33 log cfu/ g in SMP.