Aqueous Sodium Chloride Solutions Research Articles

Effects of electric double layer on nanoscale boiling: Molecular dynamics approach

Electric double layers (EDL) are formed in aqueous solution of electrolytes near electrically charged wall. Such EDLs play a crucial role in many interfacial phenomena, among which a nanoscale boiling process was studied with molecular dynamics simulations. Evaporation and boiling were investigated with aqueous solution of sodium chloride (NaCl), a typical inorganic electrolyte, in contact with an artificially charged platinum substrate. The heating area temperature of the substrate was controlled in a range from 500 to 800K. The results indicate that the surface charge and the formed EDL suppress the bubble nucleation due to strengthened interaction between liquid molecules and the substrate. It was also shown that water molecules in the EDL exhibit orientational ordering even at higher temperatures.

A New Concept for Interpretation of the Viscoelastic Behavior of Aqueous Sodium Carboxymethyl Cellulose Systems.

Viscoelastic behaviors of aqueous systems of commercially available sodium carboxymethyl cellulose (NaCMC) samples with the degrees of substitution (DS) of approximately 0.68 and 1.3, and the weight-average molar masses (Mw) higher than 200 kg mol-1 dissolved in pure water and aqueous sodium chloride solutions were investigated over a wide concentration (c) range of NaCMC samples. The dependencies of the specific viscosity (ηsp), the average relaxation time (τw), and the reciprocal of the steady-state compliance (Je-1) on c were discussed. The relationships ηsp ∝ c3, τw ∝ c2, and Je-1 ∝ c, characteristic of the rod particle suspensions, were clearly observed in a range lower than the c where the critical gel behavior was observed. Thus, a new concept based on the rheology of rod particle suspensions was employed to interpret the viscoelastic behaviors obtained in the c range. In this context, NaCMC polymer molecules are assumed to behave as extended rod particles with length (L) and diameter (d), including effective electrostatic repulsive distances, due to the dissociation of Na+ in aqueous systems. Thus, the number density of polymer molecules is given to be ν = c/Mw, and viscoelastic parameters such as ηsp, τw, and Je-1 are calculated using the theoretical model for rod particle suspensions proposed by Doi and Edwards. This concept reasonably described not only the viscoelastic data obtained in this study but also those from other groups using NaCMC samples with different DS and Mw values.

Anti‐fouling capacity enhancement of thin‐film composite polyamide membrane by chitosan graft polymerization methods

AbstractThis study aimed to improve the anti‐fouling properties of a thin‐film composite polyamide membrane by modifying it with chitosan and acrylic acid using UV‐induced and Redox‐initiated graft polymerization methods. The modified membrane's separation performance was evaluated by measuring the flux and retention of sodium ions in water during filtration. The anti‐fouling capacities of the modified membranes were determined by measuring the maintained flux ratios and irreversible fouling factors during the 8‐h filtration of aqueous solutions of sodium chloride at different concentrations (1000 and 10,000 ppm). In addition, by evaluating the membrane's surface properties using various methods, including field emission scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy, and water contact angle measurements, we have demonstrated the validity of the experimental results. Our results showed that the grafted membranes under UV irradiation or redox initiators had enhanced anti‐fouling properties while maintaining salt retention. The modified membranes fabricated by UV‐induced or Redox‐initiated technique had superior anti‐fouling capabilities, with irreversible fouling factors and maintained flux ratios of around 8% and 43%, respectively, after 8 h of filtration, compared to only 12% and 36% for the unmodified membrane. These findings suggest that the modified membranes have the potential for use in filtration systems to prevent the fouling phenomenon.

Effects of different freezing methods on muscle qualities and myofibrillar protein properties of red drum (Sciaenops ocellatus) during storage

The freezing of aquatic products without causing significant changes in quality is recently attracting much attention. In this study, the effects of air freezing (AF, -20°C), blast freezing (BF, -35°C), liquid nitrogen freezing (LNF), and immersion freezing (IF, -35°C) by 20% ethanol, 20% propylene glycol, 10% glycerol, and 10% sodium chloride aqueous solutions, respectively, on muscle qualities and myofibrillar protein properties of the red drum were investigated. The results indicated that the freezing rate of IF was 2.66 cm/h, which was 6.33 times higher than that in AF groups. Compared with AF and BF, the ice crystals were smaller and more uniformly shaped, with properties of lower water migration and less texture softening after cryogenic liquid freezing of IF and LNF group aquatic products. Immersion freezing showed the same superiority in maintaining the freshness of fish fillets and retaining the protein structure as liquid nitrogen storage. Overall, IF has similar effects to LNF in maintaining muscle qualities and myofibrillar protein properties. This study describes a new freezing method that uses 20% ethanol, 20% propylene glycol, 10% glycerol, and 10% sodium chloride aqueous solutions as immersion freezing medium. The multi-compound freezing medium has the potential to be used for the freezing of aquatic products.

Diffusivities in water or aqueous solutions of sodium chloride with dissolved hydrogen and methane by dynamic light scattering

Knowledge of diffusion in water or aqueous solutions of sodium chloride with dissolved hydrogen and methane is important for geological hydrogen storage. This study examines the accessibility of diffusivities in the corresponding mixtures through dynamic light scattering at macroscopic thermodynamic equilibrium and provides corresponding data for hydrogen-storage-relevant temperatures T up to 393 K and pressures up to 20 MPa. The thermal and mutual diffusivities are simultaneously accessible in mixtures of water and hydrogen. Moreover, for water with dissolved mixtures of hydrogen and methane, the thermal diffusivity and an apparent diffusivity related to the diffusion of the gas mixture can be accessed. In aqueous solutions of sodium chloride at T > 300 K, a strong molecular association leading to a quasi-static light-scattering pattern in the liquid sample was observed, which hindered the determination of the molecular gas diffusivities. However, the salt diffusion coefficient was accessible for all T values.

Robust and stable organic sulfonate sodium salt-coated superhydrophilic mesh for ultra-fast gravity-drive oil-water separation

Due to its special wetting behavior and high selectivity, super-wetting mesh is considered as an ideal candidate material for efficient separation of water/oil mixture. However, the oil-water separation mesh suffers from the problems of poor stability and durability, leading to the failure of the separation. In this paper, a robust and stable superhydrophobic/superhydrophilic copper mesh had been successfully prepared by decorating the copper mesh via the chemical grafting of the 3-thiol-propyl trimethoxysilane (KH590) and the subsequent reaction with 2-acrylamide-2-methylpropane-1-sulfonate sodium (AMPS). It showed that the KH590 condensation compound was tightly coated on the surface and the superhydrophobic copper mesh (SUCM) possessed excellent superhydrophobicity towards various liquid droplets with a WCA of higher 150° and a sliding angle lower 5°, while the superhydrophilic copper mesh (SICM) had promising anti-oil pollution property with WCA near 0°. The SUCM and SICM also had excellent acid and alkali resistance. The obtained SICM had preeminent separation efficiency higher 99% and extremely high permeability flux of 33,441 L·m−²·h−¹ for gravity-driven toluene-water separation, and possessed excellent recyclability even after 20 cycles. Moreover, the SICM could be used to separate the oil-water mixture of aqueous solution with different pH (pH=5/7/8) and aqueous sodium chloride solution with different concentrations (5%/25%/50%/saturated aqueous sodium chloride solution). In addition, the SICM had outstanding anti-abrasion mechanical stability. This work provided a simple and effective method for the preparation of special wettability materials with excellent acid/alkali resistance and mechanical stability, and promoted the practical application of oil/water separation mesh.

Corrosion behavior of two Cu‐based shape memory alloys in NaCl solution: An electrochemical study

AbstractThe corrosion behavior of two different Cu–Al–Mn–Ni alloys, pseudoelastic and pseudoplastic, was studied in a 0.6 M sodium chloride aqueous solution by monitoring the open circuit potential for 100 h and characterizing the resulting corrosion products. Electrochemical impedance spectroscopy analysis detected three processes related to the electrochemical double layer, a passive film and a diffusive contribution associated with the dissolution/precipitation of corrosion products. Potentiodynamic scans revealed a cathodically controlled corrosion mechanism and the presence of active–passive behavior at anodic potentials for both alloys studied. Polarization of the samples at selected potentials in the anodic branch allowed the investigation of the reactions involved, highlighting an improved corrosion resistance of the pseudoelastic alloy. The corrosion rates of the pseudoelastic and pseudoplastic alloys, after 100 h of immersion, were determined to be 0.007 and 0.011 mmpy, respectively. The post‐experiment characterization was carried out by means of scanning electron microscopy, micro‐Raman spectroscopy and X‐ray diffraction, supporting the electrochemical results.

Electrochemical conversion of contaminant p-nitrophenol to p-aminophenol and high-value p-quinones: Mechanism, kinetics and modeling

Understanding the chemistry of contaminant p-nitrophenol (p-NP) in electrochemical systems is of importance to remove it from wastewater and to produce high-value products such as quinones. In this study, redox experiments in a system initially containing an aqueous solution of sodium chloride and p-NP at pH 5 and 25 °C were performed in an electrochemical reactor with low-cost steel electrodes. The reactor was operated at 0.1 and 0.2 A, and at initial p-NP concentrations of 4.04×10−5, 6.97×10−5 and 10.3×10−5 M. Air and argon were bubbled at the bottom of the cathode to have solutions saturated with O2 (7.7 mg L−1) and free of dissolved O2. At these conditions p-NP was completely converted to less toxic and more valuable p-hydroquinone and p-aminophenol in an hour. The reaction rates were individually controlled by the steps of electron transfer and adsorption of p-NP at the cathode surface. In the presence of dissolved O2, p-hydroquinone and p-aminophenol were intermediate species oxidized to p-benzoquinone, and p-quinoneimine in the greatest amount, respectively. The rate constants for the reactions were determined on the basis of kinetic results obtained by liquid chromatography and spectrophotometry. The suggested mechanism, and the innovative kinetic model involving Langmuir-Hinshelwood rate expressions for the surface reactions, were consistent with results from mass spectrometry and total organic carbon. For the first time for this kind of kinetic model, it was also able to reproduce a large set of kinetic data of electroreduction of p-NP with iron electrodes obtained by independent researchers at several different conditions.

Application of Slightly Acidic Electrolyzed Water as a Potential Sanitizer in the Food Industry

The food industry has extensively explored postharvest microbial control, seeking viable technologies to ensure food safety. Although numerous chlorine-based commercial sanitizers serve this purpose, many are plagued by constraints such as instability and diminished disinfectant efficacy. These issues arise from exposure to organic matter in wash water, light, or air. As an innovative and promising alternative, slightly acidic electrolyzed water (SAEW) has emerged, captivating attention for its robust sterilization potential and eco-friendliness in agricultural and food sectors. SAEW generated via electrolysis of a diluted hydrochloric acid (HCl) solution with concentrations ranging from 2 to 6% or aqueous solution of sodium chloride (NaCl) in a nonmembrane electrolytic chamber is reported to possess equivalent antimicrobial properties as strong acidic electrolyzed water (StAEW). In contrast to traditional chlorine sanitizers, SAEW leaves less chlorine residue on sanitized foods such fresh-cut fruit and vegetables, meat, poultry, and aquatic products due to its low available chlorine concentration (ACC). Its near neutral pH of 5 to 6.5 not only renders it environmentally benign but also mitigates the production of chlorine gas, a contrast to low pH conditions seen in StAEW generation. The bactericidal effect of SAEW against various strains of foodborne pathogens is widely believed and accepted to be due to the combined action of high oxidation-reduction-potential (ORP) reactions and undissociated hypochlorite/hypochlorous acid (HOCl). Consequently, a burgeoning interest surrounds the potential of SAEW for sanitation in the food industry, offering an alternative to address shortcomings in sodium hypochlorite solutions and even StAEW. It has been hypothesized from a number of studies that SAEW treatment can increase the quality and nutritional value of harvested fruits, which in turn may enhance their ability to be stored. Therefore, SAEW is not only a promising sanitizer in the food industry but also has the potential to be an efficient strategy for encouraging the accumulation of bioactive chemicals in plants, especially if it is used extensively. This review encapsulates the latest insights concerning SAEW, encompassing its antimicrobial effectiveness, sanitization mechanism, advantages vis-à-vis other sanitizers, and plausible applications across the food industry.

Examination of the Effects of Taheri Consciousness Fields on the Physicochemical Properties of Water in Pure and Normal Saline Forms

In this issue, water, as a crucial molecule in Earth's structure and the formation of life, has been selected. The application of TCFs in diverse experiments on water molecules, in both normal saline and pure forms, provides the opportunity to elucidate the effects of TCFs on the level of these vital molecules. In this issue, besides examining the effects of these fields on various properties of pure water molecules, a 0.9% sodium chloride aqueous solution, commonly known as normal saline, has also been utilized. This solution is considered the most abundant aqueous solution in nature and a medicinal compound for humans. These studies investigate some of the physical and chemical properties of water, such as pH, temperature, electrical conductivity, optical absorption, and light scattering, under the treatment of TCFs in comparison to the control group.

Complete thermal characterization of liquids by front photopyroelectric configuration using the reference sample method

We explored the use of the front photopyroelectric (FPPE) configuration and the reference sample method to determine the thermal properties of liquid samples such as extra virgin olive oil and aqueous glycerol (GL), ethylene glycol (EG), and sodium chloride (NaCl) solutions. The thermal diffusivity (α) and thermal conductivity (k) were determined from photopyroelectric phase and amplitude signals, respectively, using water as a reference. The thermal effusivity (e) and volumetric heat capacity (ρc) were also determined based upon both obtained thermal properties. All thermal properties of GL and EG in aqueous solutions decrease as their volume fraction increases at an average rate of 5% for concentrations higher than 20% and between 23% and 10% for concentrations less than 20%. The Matvienko and Mandelis’ model for α and our proposed expression for ρc described this trend with a reliable approximation to the experimental data with R 2 about 0.97 and 0.99, respectively. Moreover, the frequency of a specific angle is proportional to α as established by the theory for the phase signal for thermally thick samples. In the case of aqueous NaCl solutions, the α and k values were slightly below 4.6% and 3% from water values reported at room temperature. The proposed method allows the simultaneous determination of α and k by using only the FPPE configuration with test and reference liquid samples, reducing time and uncertainties from the use of more than one experimental setup, and providing the complete thermal characterization.

Behavior of boron contained in foil brazing filler metal and corrosion resistance in dilute sulfuric acid and sodium chloride aqueous solutions

Behavior of boron contained in foil brazing filler metal and corrosion resistance in dilute sulfuric acid and sodium chloride aqueous solutions

In-situ derivatisation, extraction, and preconcentration of some phenolic compounds from water and wastewater samples through cold-induced homogenous liquid-liquid extraction followed by dispersive liquid-liquid microextraction

ABSTRACT In this study, an efficient sample preparation method for the extraction and preconcentration of some phenolic compounds was developed before their analysis with gas chromatography equipped with a flame ionisation detector. Initially, cold-induced homogeneous liquid-liquid extraction was performed for the extraction of polar target compounds from petrochemical, pharmaceutical, well water, and city sewage samples. In the following for more preconcentration, dispersive liquid-liquid microextraction was carried out to enhance enrichment factors. For this purpose, in a glass test tube, a mixture of acetonitrile and acetic anhydride (derivatisation agent) was added to the sample solution in which sodium chloride and sodium carbonate were dissolved. A homogeneous solution was obtained. The solution was frozen by immersion of the tube in liquid nitrogen for a few seconds. The frozen solution was removed from the bath and let stand for a few minutes at room temperature. The organic phase (acetonitrile) was melted and collected on the solidified aqueous solution. The organic phase containing the derivatised phenols was removed and mixed with µL-level of 1,2-dibromoethane and injected into an aqueous solution of sodium chloride. The created cloudy solution was centrifuged and 1 μL of the sedimented phase was injected into the separation system. The effective parameters including the type and amount of base, amount of derivatisation agent, ionic strength of solutions, type and volume of solvents, and vortexing time were investigated. High extraction recoveries (80–92%) and enrichment factors (412–478), wide linear ranges, and satisfactory limits of detection (4.82–9.27 μg L−1) and quantification (14.25–30.86 μg L−1) were obtained.

Study of Molecular Interactions of the H-1 Antihistamine Drug Chlorpheniramine (CP) in Water and in Aqueous Solutions of Urea, Glucose, and Sodium Chloride at Different Temperatures

Study of Molecular Interactions of the H-1 Antihistamine Drug Chlorpheniramine (CP) in Water and in Aqueous Solutions of Urea, Glucose, and Sodium Chloride at Different Temperatures

Effect of ionic polarization on the static permittivity of electrolyte aqueous solutions

AbstractWe developed a theoretical model with two separate components for the description of the static permittivity of aqueous electrolytes versus concentration and temperature. The first component is due to the water molecular polarization, whereas the second component is governed by the ionic polarization. We found that the permittivity part due to the ionic polarization effect is comparable to that come from the water molecule polarization for aqueous electrolytes at ambient temperatures. The microdynamic mechanism of the phenomenon, which the static permittivity of sodium chloride aqueous solution with concentration of 2.8 mol/L holds constant with the change of temperature, is clarified. The equilibrium compensation between the decrement of the permittivity part due to the water molecular polarization and the increase of that originated from the ionic polarization as increasing temperature is responsible for this phenomenon. The dipole moment reduction of water molecules as rising temperature is also confirmed by the model.

Mo-based bio-derived carbon catalyst enables a tandem dehydration reaction for the direct synthesis of fuel precursors from fructose

In the pursuit of sustainable alternatives for petroleum fuels, bio-based hydrocarbons emerge as a promising choice. To explore this, a molybdenum catalyst supported on bio-derived carbon was developed, enabling the direct synthesis of fuel precursors from fructose. The catalyst was synthesized by varying the wt.% of molybdenum loading through hydrothermal treatment and carbonization. The NH3-TPD analysis revealed the presence of 1 mmol/g of acidic sites on best the catalyst. HRTEM and XPS analysis reveals that the majority of molybdenum is present as Mo6+. The synthesized catalyst effectively facilitated the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF), followed by hydroxyalkylation/alkylation (DHAA) of 5-HMF with 2-methylfuran. Furthermore, compared to commercial Brønsted acid catalysts, the synthesized catalyst demonstrated remarkable performance, achieving complete fructose conversion with 36% selectivity towards the DHAA product. Moreover, an innovative approach was developed for the separation of 5,5′-((5-((5-methylfuran-2-yl)methyl)furan-2-yl)methylene)bis(2-methylfuran) and 5-HMF from dimethyl sulphoxide (DMSO) using a saturated aqueous sodium chloride (NaCl) solution in tetrahydrofuran (THF). This developed method, utilizing the bio-derived catalyst with efficient catalytic performance and effective product separation from DMSO, shows great promise for directly synthesizing fuel precursors from fructose and advancing sustainable fuel production.

Hydrogen Production Properties of Aluminum–Magnesium Alloy Presenting β-Phase Al3Mg2

In this study, aluminum–magnesium (Al-Mg) bulk porous materials were fabricated by using uniaxial hot pressing to control the porosity rate of the material over a wide range (up to 50%). The fabricated materials were analyzed by X-ray diffraction and scanning electron microscopy. The results demonstrated the appearance of intermetallic (IM) phase Al3Mg2, and its quantity increased with the applied pressure. In the context of the decline of global fossil fuel reserves, the revalorization of these materials by hydrogen (H2) production was investigated. Hydrolysis of the Al-Mg materials was carried out in a simulated seawater solution (aqueous solution of sodium chloride 35 g/L). The results showed the role of the porosity rate in the H2 production properties of the fabricated materials; the increase of porosity rate from 10% to 50% cuts the reaction time in half. Finally, the role of IM phase Al3Mg2 in H2 production was highlighted through galvanic coupling.

Discharge in electrospraying of highly conductive aqueous solution coated with outer ionic liquid

Discharge in electrospraying can be applied in water decontamination, dental sterilization, and spectrometry of biological samples. The discharge in electrospraying of a single liquid like the aqueous solution or the ionic liquid has been investigated, which presents different discharge characteristics such as patterns, currents and frequencies. This paper puts forward a way to actively control the discharge characteristics of liquids electrospray beyond the limitation of their own physical properties, which was accomplished by utilizing the technique of coaxial electrospray to coat the concentrated sodium chloride (NaCl) aqueous solution with a layer of ionic liquid. Previously we used this method to suppress the discharge of NaCl solution and stably electrosprayed the NaCl solution. The discharge characteristics of coaxial electrospray and the effect of the applied voltage and the flow rates of both liquids on the discharge was investigated in detail. When being electrosprayed, the NaCl solution alone discharged with pre-onset mode, pulseless corona discharge mode and streamer discharge mode, while the ionic liquid and the coaxial electrospray only discharged with the streamer discharge mode with a conical liquid shape, and less droplets were formed during the transient cone-jet emission. After being coated with the outer ionic liquid, the current, frequency and onset voltage of the discharge of the inner aqueous solution all increased. The current and frequency of the discharge of the coaxial electrospray all increased as the applied voltage increased. In addition, a numerical simulation has been conducted, which confirmed that the inner aqueous solution was strongly shielded from the external electric field by the outer ionic liquid layer. Therefore, it is plausible to actively control the discharge characteristics of the liquids through adjusting the flow rates of both liquids, the applied voltage and choosing the suitable outer liquid.

Phase equilibrium conditions in carbon dioxide + cyclopentane double clathrate hydrate forming system coexisting with sodium chloride aqueous solution

The four-phase equilibrium conditions were measured in carbon dioxide + cyclopentane double clathrate hydrate forming systems coexisting with either sodium chloride aqueous solution or pure water as a technological basis for developing seawater desalination technology utilizing clathrate hydrate formation and decomposition. The equilibrated phases included sodium chloride aqueous solution or pure water, carbon dioxide + cyclopentane double clathrate hydrate, liquid cyclopentane, and carbon dioxide gas. The experiments were performed using the batch isochoric procedure. Three different concentrations of sodium chloride in the aqueous solution were tested: 0.035, 0.070, or 0.105 in mass fraction. Pressures ranged from 0.385 MPa to 2.488 MPa. The results were compared with the equilibrium conditions for carbon dioxide and cyclopentane simple clathrate hydrate forming systems. The comparison revealed that the double clathrate hydrate is more thermodynamically stable than the simple clathrate hydrates, under a given sodium chloride concentration in the aqueous solution.

Features of the use of sodium hypochlorite in agriculture. Technology of solution preparation in a small-sized mobile device

The purpose of the presented work is to develop a technology and a small–sized device for producing electrolytic sodium hypochlorite of high activity with respect to biofactors, safe to handle and negative impact on the environment. The implementation of the electrochemical method of obtaining consists in the electrolysis of an aqueous solution of sodium chloride or seawater in an electrolyzer pretreated with high-voltage discharge pulses. The proposed technical solution makes it possible to increase the yield of electrolysis products and the reactivity of sodium hypochlorite due to the structural adjustment of both water and sodium chloride molecules. A portable low-power device for the production of hypochlorite in farms, characterized by multifunctional use, has been developed for disinfection, disinfection and deratization. The novelty of the work is confirmed by the need to develop a technology for obtaining a disinfectant by activating water with a high-voltage discharge, which improves the quality of hypochlorite for disinfection of water, organic waste from animal husbandry, pig and poultry farming, grain storage and pest control of agricultural and fruit and vegetable crops.