Chloride Brine Research Articles

Подземные источники балки Пещерная озера Баскунчак: гидрохимические особенности и эмиссия парниковых газов

For the first time, full-scale measurements of methane and carbon dioxide emissions by the chamber method were carried out in summer for groundwater sources discharged in the valley of the Peshernaya Gulch creek, located in the north-west of Lake Baskunchak. pH values, concentrations of CH4, basic ions, gross Fe and Mn were determined in the water of the sources; concentrations of CH4, H2S, organic matter, Eh and pH values, density and humidity were determined in various layers of bottom sediments (up to 27 cm). A detailed description of the identified groundwater sources was carried out, their primary morphometric and morphological characteristics were measured, as well as the flow rate. It was found that more than 10 ascending karst sources of groundwater are discharged in the Peshchernaya beam, 5 of which were active during the research period and mainly confined to the left screw of the beam. The active sources of the left screw of the beam are characterized by a small flow rate and are sodium chloride brines with a mineralization of 93.9–107.1 g/l. The bottom sediments accumulating in the sinkholes of underground sources are characterized by a neutral acid-base environment and restorative conditions. The concentrations of CH4 and ∑H2S in the sediments of the sources varied, respectively, in the range of 0.08–0.77 µg/g vl.o. and 0.023–2.63 mg/g vl.o. with minimal values for both gases in the lower less reduced layer with a low content of Sorg. The concentration of methane in the water of active sources varied from 26.3 up to 38.4 µl/l and was on average 2 times higher than in the waters of a stream fed by them and an inactive source. The specific methane flux from the water surface of active sources varied in the range of 0.6–1.5 mg/(m2∙h), which is 2 orders of magnitude lower than the specific CO2 flux of 46.4–106.1 mg/(m2∙h). The isotopic composition of carbon (δ13C) CH4 and CO2 measured in gas bubbles rising from the bottom of one of the ascending sources indicates the modern biochemical genesis of these greenhouse gases.

Cs+ Extraction from Chloride-Rich Brine Solutions Using the Calixarene Crown Ether MAXCalix

ABSTRACT We have developed an extraction method for the retrieval of Cs+ from chloridecontaining salt brine solutions. We employ the calixarene crown ether known as MAXCalix as the extractant, which exhibits a remarkable selectivity for Cs+ over Na+, K+, Mg2+ and Ca2+, with separation factors ranging from 100 to 104. The efficiency of the extraction strongly depends on the chloride concentration in the aqueous phase. Notably, when the chloride concentration reaches 4 mol L−1, we achieve a Cs+ distribution ratio of 7.9. Accordingly, the retrieval of Cs+ from the organic phase is achieved when the HCl concentration is maintained at a low level. In multicomponent chloride brine solutions, the distribution ratios for Cs+ are somewhat lower, yet still fall within the range of 4–6. Nevertheless, these ratios remain favorable for separation purposes. Additionally, the distribution ratios of Na+, K+, Mg2+, and Ca2+ offer insights into the coordination chemistry of MAXCalix. Our experimental data indicate a correlation between ionic size and distribution ratio. Cs+ forms the strongest complex, followed by K+ and Na+, while Mg2+ and Ca2+ exhibit minimal extraction, potentially due to interactions with the diluent. These findings may open new approaches for the development of a decontamination strategy tailored to address salts and brine solutions contaminated with Cs-137.

DEVELOPMENT OF SODIUM CHLORIDE BRINES TECHNOLOGY FROM HALITE WASTE

The results of a study of the composition of solid halite waste (halite dump and quarry salt) from potash production were presented in the work. The form of calcium sulfate and its localization in solid halite waste have been determined. It was established that in the quarry salt calcium sulfate was presented in the form of anhydrite and dihydrate, and in the halite dump the impurity was only in the form of anhydrite. Photomicroscopic photography of the surface of large halite crystals showed that calcium sulfate in the halite dump was localized mainly on the surface of halite, and on particles of quarry salt. Calcium sulfate crystals were pressed into the crystalline surface of halite due to the processes of dissolution - crystallization occurring under the influence of atmospheric precipitation and changes temperatures. An assessment of the influence of ultrasonic and hydromechanical effects on the treated aqueous suspension of halite waste for purification of calcium sulfate impurities was presented. The possibility of removing most of the CaSO4 without additional reagent treatment of the halite suspension has been proven. The optimal technological parameters for the duration and intensity of ultrasonic and hydromechanical effects on the treated environment have been found. It was found that ultrasonic treatment of halite in a saturated salt brine of sodium chloride at a ratio of L:S = 5:1 for 6 min with a frequency of 22 kHz, intensity of 9.4 W/cm2, amplitude of ultrasonic vibrations of 80 μm and intensive stirring allows to achieve 80% extraction of calcium sulfate from both quarry salt and halite dump. Based on the results obtained, the feasibility of using ultrasonic treatment was demonstrated and an effective technology was proposed for the preparation of sodium chloride and (or) technical salt brines with a residual calcium sulfate impurity content of less than 0.5 wt.%, which can subsequently be used in various industries.

The first data on the concentration and emission of methane and carbon dioxide in the underground sources of the Peshernaya beam of Lake Baskunchak

For the first time, full-scale measurements of methane and carbon dioxide emissions by the chamber method were carried out in summer for groundwater sources discharged in the valley of the creek of the Peshernaya beam, located in the north-west of Lake Baskunchak. The values of pH, temperature, concentration of basic ions and methane were determined in the water of the sources. A detailed description of the identified groundwater sources was carried out, their primary morphometric and morphological characteristics were measured, as well as the flow rate. It has been established that more than ten ascending karst groundwater sources are discharged in the Peshernaya gully, five of which were active during the research period and were mainly confined to the left branch of the gully. The active sources of the left side of the beam are characterized by a small flow rate and are sodium chloride brines with a mineralization of 93.9–107.1 g/l. The concentration of methane in the water of active sources varied between 26.3–38.4 µl/l and was on average more than 2 times higher than in the waters of the stream fed by them and an inactive source. The specific flow of methane from the water surface of active sources varied in the range of 0.6–1.5 mg/(m2·hour), which is 2 orders of magnitude lower than the specific flow of CO2, which is 46.4–106.1 mg/(m2·hour).

Polyampholyte-grafted silica nanoparticles for shale plugging under high-temperature and extreme-salinity conditions

Nano-/submicron-scale plugging is critical for wellbore stability during shale gas exploitation but typically fails under high-temperature and extreme-salinity conditions due to colloidal instability. Herein, polyampholyte polymers (ZP) were grafted from the surface of silicon dioxide (SiO2) nanoparticles through surface-triggered free radical polymerization to generate nanoplugging additives (SiO2-g-ZP). SiO2-g-ZP exhibited excellent colloidal dispersion stability with a nano/submicron size distribution in 35 w/v% sodium chloride (NaCl) and 11 w/v% calcium chloride (CaCl2) brines at 160 °C for a long time and over a wide pH range, and efficiently plugged 220 nm and ∼20 μm pores and 5 μm fractures at 160 °C and 3.5–5.5 MPa. Three critical aspects of observation and analysis obtained through microstructure analysis and molecular dynamics (MD) simulations helped elucidate the mechanisms that control the SiO2-g-ZP's performances: an increase in SiO2-g-ZP's hydration capability with salinity due to the antipolyelectrolyte behaviours of ZP coatings with zwitterionic nature, an efficient mitigation of Na-bent agglomeration even at harsh conditons due to the preferential adsorption of SiO2-g-ZP rather than Na+, Ca2+ and Cl− on Na-bent, and the presence of a nanosilica core and rigid groups and massive hydratable groups. The first two aspects caused a perfect matching of particles in muds to pores and fractures in formation and the third aspect helped enhance the SiO2-g-ZP's thermal resistance and residence in the pores and fractures. This work provides a novel approach that can be broadly generalized to address the thermal- and salt-tolerance challenges of colloidal systems used in the exploration and development of deep and complex shale formations.

Effect of Divalent Cations and Other Ions on the Tetrahydrofuran Crystal Inhibition of Quaternary Ammonium Salts-Relevance to the Efficiency of Gas Hydrate Quaternary Anti-agglomerants.

Gas hydrate anti-agglomerants (AAs) are a class of low-dosage hydrate inhibitor that are used to prevent plugging of gas hydrates in oil and condensate upstream flow lines. Industrial AAs are mostly cationic surfactants which are "hydrate-philic", i.e., they are designed to interact with and modify gas hydrate crystal growth. Tetrahydrofuran (THF) hydrate crystal growth studies have been used for many years to determine useful functional groups to incorporate into AA surfactants. In particular, quaternary ammonium and phosphonium salts with optimized alkyl groups show good THF crystal growth inhibition, which is a key property for AAs. AAs are often screened and tested in model brines containing sodium chloride despite the produced water containing various divalent cations. Recent studies have shown that AAs performed better when tested in brines containing both sodium and calcium ions rather than just sodium ions. Here, we present THF hydrate crystal growth studies on quaternary ammonium and phosphonium salts and other related molecules including guanidinium salts and amine oxides. Tests were carried out with a variety of cations including sodium, calcium, magnesium, and lithium at identical pre-determined subcooling, in order to investigate the effect of the ion size and charge density on the crystal growth inhibition. We also investigate the effect of using the more polarizable iodide ions compared to chloride ions. Our results show that crystal growth inhibition in solutions with calcium ions is somewhat greater than that with sodium ions, in agreement with past studies on the effect of AA performance with mono- and divalent cations. However, the variation does not seem to be primarily related to the charge density and polarizing ability of the cations. This study therefore provides evidence that AAs should be tested in brines containing all the ions present in the produced water and not just sodium chloride brine.

Investigation of The Effect of Temperature and Contamination on Properties of Saturated Salt-Base mud

The most difficult challenge that can be encountered when drilling a salt section is the difficulty of controlling the change in drilling fluid properties. In addition, the challenging geological environment was encountered. , creep behavior, slim hole drilling in salt formation have a few traits: high soluble, wash out salt section (1). The treatment did by using drilling mud that inhibits changes and is resistant to contaminants. Sodium chloride and potassium chloride brine were used to create a new mud for discussing this research, following up on changes in the properties of the new mud, simulating the conditions of Salt section (12.25'' hole) in the Noor oil field. Moreover, In this investigation studied the effect of temperature and contaminants such as salt, shale and anhydrite on new mud properties (Rheological properties, Filtration, PH with Different concentrations of Kcl & Nacl. The results indicate that the dissolution of salt formation decreases with increasing KCl concentration up to 5% for saturating NaCl salt. This reduces the contaminant impact and increases the stability of mud characteristics.

The effect of surface properties of silicon dioxide nanoparticle in drilling fluid on return permeability

The oil and gas industry faces significant challenges in drilling and completion operations, particularly with respect to formation damage and wellbore instability. One approach to mitigating these issues is the use of nanoparticle-enhanced drilling fluids, which can improve fluid filtration and reduce formation damage. However, the influence of nanoparticle surface properties on these effects is not well understood. Therefore, the aim of this study is to investigate the influence of the zeta potential of nanoparticles in drilling fluids on the filtration of drilling fluids and its effect on the permeability of porous media. The motivation behind this work is to enhance the understanding of the role of nanoparticle surface properties in improving drilling fluid filtration and reducing formation damage. The novelty of this work lies in the exploration of the influence of nanoparticle surface properties on the return permeability of porous media. Silicon dioxides were used to represent the nanoparticles, and the surface was modified by silanization with a carboxyl group. Filtration and permeability alteration were analyzed using return permeability experiments on Berea sandstone cores under overburden pressure, pore pressure, overbalance pressure, and temperatures of 3000 psi (20.68 MPa), 1000 psi (6.89 MPa), 500 psi (3.45 MPa), and 140 °F (60 °C), respectively. Bentonite-free water-based drilling fluid and sodium chloride brine were used to represent the formation fluids. The results show that the addition of non-functionalized SiO2, and low and high carboxyl functionalized SiO2 reduced the filtration by 13%, 33%, and 36%, respectively. Although the addition of nanoparticles into the drilling fluid can reduce fluid invasion into the porous media, solid invasion into the porous media can be detrimental and cannot be easily remediated in recovering return permeability. Return permeability of porous media after exposure to drilling fluids without nanoparticles and with non-functionalized SiO2 decreased by 47% and 82%, respectively. In contrast, exposure to drilling fluid with low and high carboxyl functionalized SiO2 decreased only by 21% and 15%, indicating the importance of nanoparticle surface properties in increasing the return permeability of porous media.

Targeted recovery of metals from thermoelectric generators (TEGs) using chloride brines and ultrasound

Recycling of thermoelectric materials: thermoelectric leg and copper plates removed by targeted oxidation or thermoelectric legs removed by high-intensity ultrasonication.

Gradient heating induced better balance among water transportation, salt resistance and heat supply in a high performance multi-functional solar-thermal desalination device.

Solar-driven desalination (SDD) is a promising technology for addressing water scarcity. However, how to overcome the trade-off between water transportation and heat supply of the evaporator to achieve a high evaporation rate and good salt tolerance simultaneously remains a challenge. Here, a novel all-in-one multi-functional SDD evaporator undergoing gradient heating is used. This evaporator incorporates a hydrophilic PDA (polydopamine)@CNT(carbon nanotube)/PVA (polyvinyl alcohol) aerogel with vertically aligned structures as the water evaporation layer, enabling rapid water transportation. Surrounding the evaporation layer, there is a photothermal hydrophobic CCP (cotton/CNT/polydimethylsiloxane) film that serves as the heating layer, enhancing the heat supply to the evaporation layer. This innovative design strikes a favorable balance between water transportation and heat supply, facilitating high evaporation rates and good salt tolerance simultaneously, while also maximizing electricity generation. Due to the wettability difference between the evaporation layer (PVA aerogel) and heating layer (CCP film), a record stable temperature gradient of nearly 70 °C was formed between the CCP film and the PVA aerogel under 1 sun irradiation, so that heat on the high-temperature CCP film was continuously transferred to the low-temperature aerogel through its thermal conductive network, leading to a high evaporation rate of 6.96 kg m-2 h-1 under 1 sun irradiation in 5.0 wt% sodium chloride (NaCl) brine (higher than the world average seawater salinity (3.5 wt%)). Meanwhile, high flux directional flow of brine generated 130 mV stable voltage and 120 μA circuit current. Furthermore, the evaporator illustrates good stability for consecutive 7 days of testing and shows industry-leading comprehensive performance of SDD in actual use. More importantly, it was tested in real Bohai seawater under weak natural light, and fresh water generated can meet the recommended daily intake of water for 2.6 households and the simultaneously generated voltage reaches above 60 mV. In addition, the evaporator exhibits good adsorption capacity for heavy metals and dye molecules. This simple and universal solar evaporation structure is suitable for the assembly of gradient thermal structures for most solar thermal materials reported in the literature, which provides a new route for maximizing the use of solar energy for freshwater and electricity generation.

EFFECT OF CLAY MINERALOGY AND BRINE CONCENTRATION ON THE SWELLING PROPERTIES OF SHALE.

Chemical wellbore instability is mostly attributed to the “unfavorable interaction” between the formation pore fluid, its shale constituents and the drilling fluid, this is mostly experienced in terms of shale swelling that tends to under gauge the drilled well. This study was conducted to examine the impact of brine concentration and mineralogy on the swellability of shale. Sixteen shale samples were obtained from selected wells across two selected fields (OR and OG) in the Niger Delta. X-ray diffraction analysis was carried on the shale samples to determine its mineralogy distribution. A Nacl brine solution was prepared alongside a water based mud formulated using sodium chloride brine of varied concentration. The shale samples were tested for its swellability in both brine solution formulated water based mud for 24 hours and 48 hours. Results obtained showed that there were more clay minerals (56%) across both fields and that Palygorskite was the most abundant clay minerals for both fields. Also, for the swelling test (shale-in-brine and shale-in-mud) that the shale samples swelled in both medium as expected, but to different degrees, mainly as a function of the mineralogy content of the shale and the brine concentration of the fluid in which they are immersed. The import of this goes to buttress the necessity for understanding the place of mineralogy and concentration in the study of wellbore instability caused by chemical interaction.

Temporary clogging effects induced by a sustainable anti-icing hydrogel on the hydraulic conductivity and inertia coefficient of open-graded asphalt pavements

Open-graded asphalt pavements require special winter maintenance procedures to ensure the effectiveness of anti-icing and deicing measures. A recently developed solution for this type of pavement is represented by an environmental friendly thickened bio-based salt hydrogel, which consists of a thermo-sensitive sodium chloride (NaCl) brine admixed with a gellant agent (seaweed fibers) having the ability to form a gel-like structure when hot-sprayed on a cold surface. This thin salt layer results in a long-lasting residual efficacy of the winter maintenance product and in a reduction of salt consumption, but affects the drainage capacity of the pavement. These transient clogging effects were evaluated on laboratory-made specimens through the measurement of their vertical hydraulic conductivity variations before and after the hydrogel application, using a 1-D air permeameter and a constant head water permeameter. The analyses, based on Darcy–Forchheimer model and Darcy model for lower Reynold numbers, revealed a significant short-term reduction of the hydraulic conductivity, that, anyway, tends to be almost totally restored once the critical weather event is over (after about 6 h).

Influence of aqueous sodium chloride solutions on operational properties of epoxy coatings

The main goal of the research presented in the article is to assess the impact of the destruction (degradation) of epoxy coatings, caused by the influence of a 25% aqueous solution of sodium chloride (brine), on the operational properties that determine the coatings reliability (durability). Samples of two-layer epoxy coatings (obtained from powder paints) were aged by immersing them in brine for a maximum period of 1680 h. The following criteria were used to assess the operational properties of the coatings: thickness, roughness and surface morphology, hardness, water absorption (mass increase), surface free energy. The FTIR and DSC tests performed showed a progressive development of the oxidation processes of the epoxy with the ageing period. The long-term impact of the brine resulted in the destruction of the coatings in the form of: craters, grooves, microcracks, including silver cracks. The contact of the coatings with brine also increased their: surface roughness (Ra, Rz, Rmax), thickness, mass, surface free energy, and decreased hardness and heat resistance.

Formation of calcium chloride brines in volcaniclastic-rich sediments

The Amami-Sankaku Basin, located in the Philippine Sea, records approximately 50 million years of sediment accumulation and diagenesis of volcanic ash derived from the Kyushu-Palau and Kyushu-Ryukyu arcs. Analyses of porewater and sediment samples from the 1461-m core recovered at IODP Expedition 351, Site U1438, included major and trace elements, strontium radiogenic isotope ratio (87Sr/86Sr), and taxonomic identification of archaeal classes and bacterial orders. Sediment X-ray diffraction and thin section analyses show that smectite, zeolites and chlorite are the main authigenic minerals. A multicomponent solute diffusion and reaction numerical model was developed to simulate the long-term diagenesis that took place in this sedimentary sequence and to account for the transition to a calcium chloride brine at about 670 mbsf. Numerical results indicate that 45% of the initial amount of volcanic ash has been dissolved at 750 mbsf. At this depth, 13% of the initial water (H2O) in the pore space is estimated to have been transferred to the solid phase by the formation of zeolites, which accounts for an increase in porewater chloride concentration. In contrast, dissolution of anorthite and volcanic ash combined with sodium uptake by zeolites accounts for the predominance of calcium in the brine. In the upper 160 m of the sedimentary column, the electrochemical migration of solutes causes chloride to move in the opposite direction of the concentration gradient, i.e., uphill diffusion, sustaining downward diffusion of seawater chloride into the sediments.

The effect of formate brines on the emulsification of ionic, non-ionic, and enzymatic surfactants

Environmental concerns on contamination of subsurface porous media by toxic chemicals have motivated the petroleum industry to replace them with environmentally sustainable (green) and biodegradable alternatives. Green surfactants have emerged such as sugar, enzymatic, and microbial based surfactants. However, their emulsification with different oils and salinity conditions is unknown. In this study, different oil and brine systems are tested to measure interfacial properties, rheology and emulsification of Coco Glucoside (CG), a sugar-derived surfactant; and Greenzyme (GZ), an enzymatic-environmentally friendly surfactant. Emulsification with light and medium crude oil in the presence of sodium chloride and sodium formate brines gave similar results with 10–20 μm average droplet size. However, medium-heavy crude oil with potassium formate produced 98 vol% emulsion with 3–6 μm average droplet size. Most of the emulsions demonstrated a shear thinning behaviour apart from emulsions resulting from Coco Glucoside and medium-heavy crude oil in which a clear Newtonian behaviour was observed.

Quality Improvement in Mackerel Fillets Caused by Brine Salting Combined with High-Pressure Processing.

Simple SummaryHigh-pressure processing enhanced the pasteurization effect of mackerel fillets that had undergone brine salting and improved the effect of texture hardening and fish discolouration observed after the high-pressure treatment alone. Our findings provide seafood processors as an alternative option to improve the safety of salt-brined mackerel fillets.The purpose of the study is to investigate the effects of brine salting and high-pressure processing (HPP) on the microbial inactivation and quality parameters of mackerel fillets. Mackerel fillets were immersed in 3% and 9% sodium chloride brine for 90 min at refrigerator temperature, and then treated at 300, 400, 500, and 600 MPa pressure for 5 min. The microbial counts and physicochemical qualities of the fish were examined. In comparison with fish fillets treated with brine or high pressure alone, those treated with the combination of brine salting and HPP showed significantly reduced aerobic plate count (APC) and psychrotrophic bacteria count (PBC). The hardness and chewiness of salt-brined fillets were obviously lower than those of the unsalted fillets under the same pressure condition. Thus, brine salting imparted mackerel fillets a softer texture, which compensated for the HPP-induced increased hardness and chewiness of the fillets. The L* (lightness) and ΔE (colour difference) values of the fillets increased with increasing pressure, with or without brine salting. Conversely, a* (redness) values decreased with increasing pressure. The samples treated with 3% brine in combination with 300 or 400 MPa pressure had a* values similar to those of the samples processed under similar HPP conditions alone but showed lower ΔE values than the other groups. Therefore, as a very high pressure would adversely affect the texture and colour of the fish fillets, this study suggests that immersion in an appropriate brine concentration (3%) and treatment with HPP at 400 MPa for 5 min improved or maintained the colour and texture relatively well and produced a synergistic bactericidal effect.

Use of high-frequency ultrasound to intensify the sorption of humic substances from brines

To intensify the sorption concentration of humic substances from sodium chloride brines, the use of high-frequency ultrasound has been proposed. The optimal parameters of ultrasound were experimentally established as follows: frequency of 11.0–12.0 MHz, sound intensity of 7.5–8.5 W/cm2, and duration of action not less than 2.0 min. Under the action of high-frequency ultrasound as compared to the use of low-frequency ultrasound, the degree of extraction of humic substances from brines with a concentration of sodium chloride of 150 g/l increases from 91.3–93.2% to 97.3–98.2% and from 93.2–95.0% to 98.1–99.0% on wofatit sorbent and diethylaminoethyl cellulose sorbent, respectively. In addition, the effect of high-frequency ultrasound allows quantitatively sorbing humic substances from more concentrated brines (degree of extraction 90%). Moreover, quantitative sorption of humic substances is possible up to a concentration of sodium chloride of 200 g/l and 250 g/l on the wofatit sorbent and diethylaminoethyl cellulose sorbent, respectively. We developed a method for spectrophotometric determination of the content of humic substances in brines with the lower limits of determination of 0.002 mg/l and 0.001 mg/l for humic acids and fulvic acids, respectively.

Study of the direct production of lithium phosphate with pure synthetic solutions and membrane electrolysis

This work studies a membrane electrolytic process, where a diluted lithium chloride brine solution is concentrated, while simultaneously producing lithium phosphate. This innovative process takes advantage of the alkaline pH generated in the cathodic section, allowing added phosphoric acid to be precipitated as lithium phosphate. The influence of the operation variables, such as temperature and current density, was evaluated to optimise the precipitation process. Some key findings were observed: a) the optimal conditions for the precipitation of lithium phosphate were 25 °C and 7.3 mA/cm2, as the chemical equilibrium was reached in a shorter time period (15 min) under these operating conditions; b) the efficiency and stability of the cationic membrane was favoured at 25 °C; c) it was possible to concentrate the lithium chloride brine solutions to precipitate lithium phosphate, while neutralising the alkaline pH of the cathodic section; and d) the experimental results could be explained using fundamental thermodynamics.

Investigation of the Effectiveness and Safety of the Rehabilitation Program for Patients with Long Covid Using Aquatic Training

Aim. To evaluate the effectiveness and safety of aquatic training in diluted sodium chloride bromine brine in restoring the functional state of the organism of patients with portcovid syndrome in comparison with aquatic training in fresh water. Material and methods. Specialists of the National Medical Research Centre of Rehabilitation and Balneology of the Ministry of Health of Russia conducted an open, prospective, randomized study to evaluate the effect of a course of aquatic training in a bromine sodium chloride brine pool. The study included 28 subjects, who were divided into 2 equal groups. Patients in both groups were comparable for gender (χ2 =0.45; p=0.31) and age (U=99.5; p=0.7) and all had post COVID-19 (U 09.9) as their primary diagnosis. The intervention group received a course of aquatic training (7 treatments) in a pool with bromine sodium chloride brine (well No. 69, 32 Novy Arbat Street, Moscow) with mineralization of 120 g/dm3 and its preliminary dilution to 40 g/m3. Control group – a course of aquatic-exercises (7 treatments) in a fresh water pool. Patients, after signing informed consent, underwent load tests: 6-minute walking test, laser Doppler flowmetry (“LASMA ST”, Russia), cardiointervalography (“Health Reserves-R”, Russia). Results and discussion. These data confirm the “null” hypothesis of a more favorable effect of the chemical composition of the diluted brine that acts during aquatic training on the patient’s body compared to fresh water, especially in the presence of microcirculation disorders after suffering COVID-19. The group of patients who received aquatic training in the pool with bromine sodium chloride brine revealed a significant decrease in excessive sympathetic nervous system activity (T-11.0; p=0.02) at the end of the study. According to LAZMA-ST data, there was a twofold increase in the oxidative metabolism of the cell (IOM T-16.0; p <0.01), an increase in exercise tolerance (6-minute walk test T-10.0; p =0.01). IOM increased statistically significantly threefold (U-32.0; p<0.001), mean microcirculation doubled (U 120.0; p<0.05) and BMI decreased by 20.0% (U-58.0; p<0.05) in the intervention group compared with the control group. There were no significant differences between patient groups on safety parameters (χ2= 1.36; p>0.05). These data confirm the “null” hypothesis of a more favorable effect of the chemical composition of the diluted brine that acts during aquatic training on the patient’s body compared to fresh water, especially in the presence of microcirculation disorders after suffering COVID-19. Conclusion. Aquatic training in sodium chloride bromide brine effectively reduces the sympathetic nervous system activity, increases oxidative metabolism and improves microcirculation compared to aquatic training in fresh water.

A New Method Based on a Zero Gap Electrolysis Cell for Producing Bleach: Concept Validation.

Commercial bleach (3.6 wt% active chlorine) is prepared by diluting highly concentrated industrial solutions of sodium hypochlorite (about 13 wt% active chlorine) obtained mainly by bubbling chlorine gas into dilute caustic soda. The chlorine and soda used are often obtained by electrolyzing a sodium chloride solution in two-compartment cells (chlorine-soda processes). On a smaller scale, small units used for swimming pool water treatment, for example, allow the production of low-concentration bleach (0.3 to 1 wt% active chlorine) by use of a direct electrolysis of sodium chloride brine. The oxidation and degradation reaction of hypochlorite ion (ClO−) at the anode is the major limiting element of this two-compartment process. In this study, we have developed a new process to obtain higher levels of active chlorine up to 3.6%, or 12° chlorometric degree. For this purpose, we tested a device consisting of a zero-gap electrolysis cell, with three compartments separated by a pair of membranes that can be porous or ion-exchange. The idea is to generate in the anode compartment hypochlorous acid (HClO) at high levels by continuously adjusting its pH to a value between 4.5 and 5.5. In the cathodic compartment, caustic soda is obtained, while the central compartment is supplied with brine. The hypochlorous acid solution is then neutralized with a concentrated solution of NaOH to obtain bleach. In this work, we studied several membrane couples that allowed us to optimize the operating conditions and to obtain bleach with contents close to 1.8 wt% of active chlorine. The results obtained according to the properties of the membranes, their durability, and the imposed electrochemical conditions were discussed.