Concentrated NaCl Solutions Research Articles

Raman Quantitative Measurement on the Cl− Molarity of H2O-NaCl-CO2 System: Application to Fluid Inclusions

In this study, Raman spectroscopy is applied to determine the salinity of fluid inclusions in the H2O-NaCl-CO2 system. In the work, various systems are prepared, such as H2O-NaCl, H2O-CO2, and H2O-NaCl-CO2. For the H2O-NaCl system, the addition of NaCl salts decreases the intensity of the sub-band below 3330 cm−1 but increases the intensity of the sub-band above 3330 cm−1. According to the structural analysis of the H2O-NaCl system, the spectral changes are mainly related to the interactions between Cl− and water. After the Raman OH stretching bands are fitted into two sub-bands, the intensity ratio between them is used to calculate the Cl− concentrations (molarity scale) of NaCl solutions. Additionally, based on the measured Raman spectra, the effects of CO2 on water structure may be weak. It is reasonable to ignore the impact of dissolved CO2 on Raman OH stretching bands. The procedure above can be extended to quantitatively determine the Cl− molarity of the H2O-NaCl-CO2 system. To demonstrate its reliability, this method is applied to determine the salinity of synthetic and natural fluid inclusions containing CO2.

Heat Pump Evaporation: an Alternative of Membrane Filtration System Aiming Pure Water Production

The daily electrical power generation and consumption in Hungary were analyzed, and a two-hour-long interval was specified for the 5000 MW excess power generation, and 1,500,000 MJ energy was identified as an excess. Two pure-water-producing systems (membrane-based system and heat pump evaporator) were compared to utilize this excess electrical energy at industrial scale. Heat pump evaporation was tested as an alternative method for pure water production because its role in pure water production hasn’t been discussed. Suspended-solid-free feed water was used for both systems. Lab-scale experiments proved that in the case of freshwater, the four-step membrane filtration technology can be replaced by a one-step heat pump evaporation, resulting in almost the same quality of pure water characterized by the conductivity; 2 and 4 μS/cm for membrane filtration and heat-pump evaporation, respectively. When using seawater at a lab-scale, the proposed membrane technology resulted in desalted water having a conductivity of 425 μS/cm; meanwhile, by heat pump evaporation, pure water could be attained, having a conductivity of 19 μS/cm. Considering the specific electric energy consumption at laboratory scale, the one-step heat pump evaporator surely exhibits an energy-saving method for pure water production; 6.12 MJ/L and 2.31 MJ/L were measured for membrane system and heat pump evaporator, respectively. Considering an industrial-scale make-up water demand, up-scaling calculations, including hydraulic calculations and pump selection producing the same amount of pure water, resulted in a reverse trend regarding specific electric energy consumption; 25.35 MJ/m3 and 14,850 MJ/m3 estimated for membrane system and heat-pump-evaporator, respectively. Both systems were analyzed in terms of environmental impacts. According to wastewater quality and their disposability, the wastewater of freshwater treatment can be drained into the sewage system, but in case of seawater crystallization of concentrated NaCl solutions is possible. Based on our analysis, the theoretically producible water quantity is more than physically attainable by the treatment technologies, thus more options shall be considered for the utilization of excess energy generation.

An Electrically Small Patch Antenna Sensor for Salt Concentration Measurement of NaCl Solution.

In this paper, a complementary split-ring resonator (CSRR)-based patch antenna is proposed as a microwave sensor to measure the salt concentration of NaCl solution. The microwave sensor consists of an RF-4 substrate, where a small copper disc is attached on the top as the radiator, a larger copper disc integrated with two CSRRs is attached on the bottom side as the finite ground plane, and a coaxial feeding port is introduced at the ground plane center. During salt concentration sensing, only the top disc is immersed into NaCl solution. The results indicate that the proposed microwave sensor can measure salt concentrations ranging from 5‱ to 35‱ with a maximum sensitivity of 0.367 (kHz/(mg/L)). The proposed microwave sensor is low-cost, low-profile, electrically small, lightweight, and easy to fabricate, and it also can be applied to other solutions' concentration sensing.

Molecular Dynamics Simulation of Membrane Distillation for Different Salt Solutions in Nanopores.

Nanoporous membranes offer significant advantages in direct contact membrane distillation applications due to their high flux and strong resistance to wetting. This study employs molecular dynamics simulations to explore the performance of membrane distillation in a single nanopore, mainly focusing on wetting behavior, liquid entry pressure, and membrane flux variations across different concentrations and types of salt solutions. The findings indicate that increasing the NaCl concentration enhances the wetting of membrane pores, thereby decreasing the entry pressure of the solution. However, at the same salt concentration, the differences in wetting and liquid entry pressure among various salts, including CaCl2, KCl, NaCl, and LiCl, are minimal. The presence of hydrated ions significantly reduces membrane flux. As the concentration of NaCl solutions increases, the number of hydrated ions rises, thereby lowering the membrane flux of the salt solution. Furthermore, the type of salt has a pronounced effect on the structure of hydrated ions. Solutions with Ca2+ and Li+ exhibit the smallest first-layer radius of hydrated ions. Under the same salt concentration, KCl solutions demonstrate the highest membrane distillation flux, while CaCl2 solutions show the lowest flux.

Aminomethanesulfonic acid grafted polyamidoxime fibers with hydrophilicity, salt-tolerance and antimicrobial properties for highly efficient uranium extraction from seawater

Uranium extraction from seawater plays a key role in redefining the declining uranium reserves to afford sustainable nuclear power. However, it is an urgent need to develop adsorbents simultaneously possessing enhanced efficiency, collect ability, salt resistance, antibacterial properties and economy to massively extract uranium from seawater. Herein, aminomethanesulfonic acid grafted polyamidoxime fibers (PAO-AMS-A) with hydrophilicity, salt resistance and antibacterial properties were prepared. The resulting fibers display high salt resistance and high uranium uptake capacity, providing the fibers a very high adsorption efficiency of 554.09 mg g−1 in pure uranium solution, 205.43 mg g−1 and 473.44 mg g−1 in 8 ppm and 20 ppm uranium spiked seawater and 10.04 mg g−1 in real seawater, respectively. Furthermore, the material exhibited good salt tolerance, and the uranium adsorption capacity was still as high as 597.97 mg g−1 in high concentrations of NaCl solution. Note that PAO-AMS-A has also good antibacterial activity, the antibacterial rate against bacteriais cultured in seawater is up to 93.49 %. Overall, PAO-AMS-A fibers are promising in industrial uranium extraction from seawater due to their high adsorption efficiency, salt resistance and antimicrobial properties.

In-situ growth of Ni, Co-Prussian blue nanocubes on molten salt etched lamellar Ti3C2Tx/Ni for enhanced hybrid capacitive deionization

The design and development of high-performance electrode materials are crucial for improving the desalination efficiency of hybrid capacitive deionization (HCDI). In this study, a Ti3C2Tx/Ni/NiCo-PBA composite is synthesized by in-situ growing NiCo Prussian blue (PB) nanocubes on Ti3C2Tx/Ni sheets, serving as an electrode for HCDI. The Ti3C2Tx sheets provide excellent conductivity and a suitable substrate for the growth of NiCo-PBA nanocubes. The Ni nanoparticles help prevent the oxidation of Ti3C2Tx sheets, and provide a source of Ni for NiCo-PBA synthesis. Additionally, the NiCo-PBA nanocubes effectively inhibit re-stacking of Ti3C2Tx sheets, enlarge crystal lattice spacing, and facilitate diffusion and storage of salt ions. Consequently, the AC||Ti3C2Tx/Ni/NiCo-PBA HCDI device exhibits a high salt removal capacity of 36.62 mg g−1, low energy consumption of 11.14 Wh m−3, and water recovery of 61.86 %. Importantly, the AC||Ti3C2Tx/Ni/NiCo-PBA device achieves a good salt removal capacity of 53.22 mg g−1 in a high concentration NaCl solution (2000 μS cm−1). After 20 cycles, the desalination capacity remains stable, and the structure of Ti3C2Tx/Ni/NiCo-PBA is intact, indicating excellent cycling stability. Additionally, the desalination mechanism of Ti3C2Tx/Ni/NiCo-PBA electrode is thoroughly investigated.

Phase diagram of NaCl–water by computer simulations: performance of non-polarizable force-fields

This study evaluates the capabilities of two new ion force fields (Tanaka [Yagasaki et al. JCTC 2020] and Madrid-2019 [Zerón et al. JCP 2019]) in conjunction with the TIP4P/2005 model for water in reproducing the NaCl–water phase diagram using molecular dynamics direct coexistence simulations. The performance of those force-fields is critically compared with the phase diagram recently reported for the Joung Cheatham-TIP4P/2005 force-field [Bianco et al. JCP 2022]. Excellent agreement between the three force-fields and experiments is found for the ice-solution line due to the dominance of the water model in the location of this line. For the NaCl-solution line, the Tanaka and the Madrid-2019 models accurately predict solubility at ambient temperature, but they underestimate somewhat the experimental line as temperature increases. The JC model underestimates NaCl solubility both at ambient and at high temperatures. All models underestimate the stability of the NaCl·2H 2 O solid, which remains metastable with respect to NaCl. Equilibration of the NaCl·2H 2 O-solution system is challenging at low temperatures due to the slow diffusion of concentrated NaCl solutions. The phase diagrams obtained serve as a foundation for studying crystal nucleation, and solid-solution interfaces, and provide very valuable information for the development of imporved NaCl–H 2 O force-fields.

Effect of spacing, concentration of NaCl solution, and biasing of graphite electrodes towards conductometric sensor response

Effect of spacing, concentration of NaCl solution, and biasing of graphite electrodes towards conductometric sensor response

Effects of chemical solution components on the contact angle of typical minerals in soil: quartz, orthoclase and plagioclase

Different chemical solutions can significantly change the contact angle (CA) of soil, but few studies have studied the change rule and action mechanism of the CA from the mineral composition of soil essence. In unsaturated soil mechanics, the CA is an important parameter to calculate the wet suction between soil particles in unsaturated soil. When the chemical composition of the soil pore liquid changes, the CA will also change, which will affect the wet suction and other parameters, thus changing the macroscopic mechanical properties of the soil. In this study, the CA of air-solution-mineral phases with different solution components (pH, type and concentration of salt solution) of different minerals (quartz, orthoclase and plagioclase) were measured. The results show that the CAs of quartz, orthoclase and plagioclase all rise first and then drop with the rise of pH. The peak CAs are pH = 5, pH = 4 and pH = 3, respectively. Quartz, orthoclase and plagioclase all have valley values in different concentrations of NaCl and KCl solutions. In CaCl2 solution, only quartz has valley value, while orthoclase and plagioclase increase monotonously. Quartz in soil plays a main role in the influence of soil CA, followed by orthoclase and plagioclase. The CA of different minerals in different chemical solutions is mainly controlled by electric double layer interaction and functional groups interaction. In different salt solution environment, in addition to the above two effects, the mineral CA is also affected by the surface tension.

Synthesis of MnFe2O4 Spinel on Rusted Q235 Steel Surface and Its Corrosion Resistance Properties.

Corrosion of steel is an issue that cannot be ignored in contemporary society. Due to large-scale corrosion, it is urgent to develop a surface treatment process that enhances the corrosion resistance of steel, allowing for application in various scenarios as needed. This study aims to investigate a novel surface treatment process to extend the service life of corroded Q235 steel, reduce its sensitivity to corrosion, and enable its use in multiple environments. This study employs the sol-gel method, using manganese nitrate solutions of varying concentrations to treat the surface of Q235 steel after different electrolysis times. The optimal conditions for precursor preparation were found to be a Mn2+ concentration of 0.1 mol/L and an electrolysis time of 2 h. Electrochemical tests using NaCl solutions of different concentrations revealed a significant reduction in the corrosion current for the composite coating based on Q235 steel treated with this method in NaCl solutions with wt.% = 1, 2, 3, 4, 5. Furthermore, the resistance to corrosion was strongest in the NaCl solution with a concentration of 1 wt.% where the corrosion current decreased from 24.8 µA/cm2 to 6.79 µA/cm2. Additionally, the coating was found to be diffusion-controlled in the early stages of the corrosion process and charge transfer-controlled in the later stages. The MnFe2O4 spinel coating demonstrated the greatest enhancement in corrosion resistance in the wt.% = 1 NaCl solution.

Galvanic Corrosion Behavior of Zn and Al Couples in NaCl Solution

Multi-materialization is being promoted in automotive structural materials, and fuel economy is being improved by replacing steel with aluminum and other lightweight metallic materials. Automotive steel is often galvanized for corrosion protection, and galvanic corrosion of aluminum and zinc in an atmospheric environment is a very important issue in evaluating automotive durability. Zinc is usually considered to be an anode when combined with aluminum, but its galvanic corrosion behavior can be complicated by environmental conditions because the corrosion potentials of the two are relatively close. Therefore, the objective of this study is to investigate the galvanic corrosion behavior of the couples consisting of zinc and aluminum under corrosive environmental conditions.The galvanic couple used in this study was fabricated from AA1050 Al and zinc plates. The width and length of both plates are 10 mm and 15 mm, respectively. After connecting lead wires to each plate, both plates were embedded in epoxy resin. To fabricate coplanar galvanic couples in this study, both plates were placed separately along the surface from a gap size of 500 um. The surfaces of the galvanic pairs were polished with SiC paper to JIS 2000 grit and cleaned with EtOH. The test solutions used in this study were aqueous NaCl solutions of various concentrations from 0.01 to 2 M, prepared with Milli-Q water and reagent grade chemicals. Galvanic currents and corrosion potentials were measured to investigate the galvanic corrosion behavior of the couples after 72 hours of galvanic corrosion experiments in the test solutions.The results of the galvanic corrosion test showed that the immersion potentials of the galvanic couples were lower at higher NaCl concentrations. The galvanic current decreased with immersion time, finally reaching about 1 uA in all NaCl solutions. The results of the electrochemical impedance measurements for galvanic couples in various NaCl concentrations showed that the impedance gradually increased with immersion time. It was also found that the impedance can be expressed as an electrical equivalent circuit consisting of two time constants, and that the impedance increases at intermediate frequencies between 0.1 and 1 Hz, which is thought to correspond to the dissolution reaction of Zn. This was the same trend as the behavior of the galvanic current. These results suggest that prolonged immersion reduces the galvanic current and the dissolution rate of zinc due to the passivation of the A1050 surface and the suppression of cathodic reactions.

CO2 solubility in aqueous solution of salts: Experimental study and thermodynamic modelling

AbstractThere are many economic obstacles and complex engineering problems associated with CO2 capture and storage in saline aquifers that need to be addressed. Overcoming such challenges requires precise knowledge on the fluid phase equilibria of CO2‐brine systems. Having accurate CO2 solubility data over a wide range of temperature and pressure can greatly assist in resolving these obstacles by improving the performance and accuracy of the thermodynamic modeling and subsequent CCS engineering success.CO2 solubility in pure water and NaCl solutions has been widely studied in the literature, however, there is a lack of data on CO2 solubility at lower temperatures (below 298 K). Furthermore, limited phase equilibria data are available for CO2 solubility in CaCl2, MgCl2, and KCl solutions at elevated temperatures (i.e., T > 323.15 K).In this work, the phase equilibria of CO2 and brine systems are investigated experimentally and theoretically. In this study, solubilities of CO2 in pure water and various concentrations of NaCl (10, 15, 20, and 22 wt%), KCl (10, 15, and 22 wt%), CaCl2 (7.5, 10, 15.7, and 23.4 wt%), and MgCl2 (6.7, 11, 18, and 29 wt%) aqueous solutions are reported. All CO2 solubilities were measures at 323.15, 373.15, and 423.15 K and over various pressure ranges, while solubilities in 10 and 20 wt% NaCl aqueous solutions were also measured over the temperature range of 263 to 298 K and pressures up to the hydrate dissociation pressure of each system. Equation of state modelling using the PC‐SAFT and the Cubic Plus Association equations of state, is performed in the theoretical part of the study to validate the measured solubility data. © 2024 The Author(s). Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Sodium doping and control during the preparation of α-hemihydrate gypsum in NaCl solution

Transformation of phosphogypsum (PG) into α-hemihydrate gypsum (α-HH) in sodium salt solution is disturbed by the doping of Na+, which causes the frost of Na+ doped α-HH. In this study, the content evolution of Na+ impurities into α-HH was clarified during the hydrothermal process at 95 ℃, the frost phenomenon of hardened gypsum containing Na+ impurities was observed and controlled. The results show that increasing the initial NaCl concentration from 5 % to 25 % can promote the phase conversion of PG into α-HH within 30 min, but this will increase the Na2O content in the product from 0.08 % to 4.37 %, which is due to the formation of the undesirable phase Na2SO4·5CaSO4·3H2O. The content of Na+ impurities entering α-HH presents a non-linear increase with the NaCl solution concentration and reaction time, which can be well described by Boltzmann function. An obvious frost phenomenon of the hardened plaster of Na+ doped α-HH can be observed after curing 3 d, and the frost is identified as Na2SO4. This work further demonstrates the feasibility that the addition of CaCl2 in NaCl solution is an effective approach to control the doping of Na+ into α-HH, the Na2O content decreases to 0.97 % in the mixed solution of 17.5 % NaCl and 10 % CaCl2, this helps to eliminate the frost phenomenon and improve the mechanical strength of α-HH.

Identification of genetic loci for salt tolerance in Brassica napus at the germination stage using a genome-wide association study

Brassica napus is a leading crop used to repair and utilize saline-alkali land. Cultivating salt-tolerant varieties of B. napus is therefore an effective means of increasing the productivity of saline-alkali land. However, the molecular regulation of salt tolerance during germination in B. napus is still unclear. In this study, seeds from an association panel containing 202 diverse accessions were treated with different concentrations of NaCl solution (200, 250, and 300 mM), and their relative germination rates (RGRs) were calculated on Days 3 and 7 after treatment. Based on phenotypic data obtained over six experiments, a total of 2749 single nucleotide polymorphisms (SNPs) significantly related to RGR were identified using a genome-wide association study (GWAS) analysis, and eight candidate genes were identified in candidate intervals. The RGR of seeds treated with 250 mM NaCl for 7 days was identified as a useful index of salt tolerance in B. napus, and 10 accessions with RGRs of 90–98 % were screened as excellent salt-tolerant germplasm resources. Finally, two of the identified SNPs were designed as SNP markers to screen salt-tolerant germplasm resources. These results provide a theoretical basis on which to determine the molecular mechanism of salt tolerance in B. napus at the germination stage.

Thermodynamic description of U(IV) solubility and hydrolysis in chloride systems: Pitzer activity model for the system U4+–Na+–Mg2+–Ca2+–H+–Cl––OH––H2O(l)

This study presents updated chemical, thermodynamic, and activity models for the system U4+–Na+–Mg2+–Ca2+–H+–Cl––OH––H2O(l) derived using the Pitzer formalism and a strict ion interaction approach. The models build on comprehensive solubility datasets in dilute to concentrated NaCl, MgCl2, and CaCl2 solutions. The Nuclear Energy Agency-Thermochemical Database (NEA-TDB) selection of solubility and hydrolysis constants in the reference state were taken as anchoring point, and were extended further with the solid nanocrystalline phase UO2∙H2O(ncr) and the ternary complex Ca4[U(OH)8]4+. The former was identified in long-term solubility experiments at ambient conditions, whereas the latter has been selected in analogy to Th(IV), Np(IV), and Pu(IV) considering experimental evidences available for these An(IV) in alkaline, concentrated CaCl2 solutions. These models represent an improved tool for the calculation of U(IV) solubility and aqueous speciation in a variety of geochemical conditions including concentrated brine systems relevant in salt-based repositories for nuclear waste disposal.

The Impact of Drought and Salinity Stress on the Physiological Growth of Fontanesia Fortunei Carr.

In order to understand the drought resistance and salt tolerance of maple leaves of Fontanesia fortunei Carr. In this study, seeds of Fontanesia fortunei Carr. were treated with different concentrations of PEG and NaCl solutions to investigate their effects on growth and physiology. The results demonstrated that the control group had the highest germination rate. PEG had a significant impact on root length but a minimal influence on plant height, with mild drought stress promoting root growth. Increasing concentrations of PEG were associated with higher MDA content, peaking at 10% concentration, while SOD activity reached its maximum at 10% PEG concentration. When the NaCl concentration was 0%, seedling root length and plant height were both maximized. NaCl primarily influenced root length but had a minor effect on plant height. Maximum MDA content was observed at 0.8% NaCl concentration, whereas SOD activity reached its peak at 0.6% NaCl concentration. This study has significant implications for landscape architecture and horticultural production.

The Effects of Mother Tree Size and Flowering Period on Salt Tolerance of <i>Tamarix Austromongolica</i> Seeds in the Yellow River Delta

<i>Tamarix austromongolic</i>a is a two-season flowering plant with a spring and summer flowering period and both flowering periods produce viable seeds, with flowering extending from mid-May to October and seed maturation from mid-June to October. In order to reveal the germination pattern of <i>T. austromongolica</i> seeds in the Yellow River Delta region, this study investigated the salt tolerance of seeds of different age mother trees during the spring and summer flowering periods in the region. Spring and summer flowering seeds of different ground diameter mother trees in the <i>T. austromongolica</i> forest in the region were collected and subjected to seed germination experiments under different concentrations of NaCl solution. The results showed that the diameter grade of the mother tree had a significant impact on seed germination, but had no significant effect on early seedling growth (except for the root length of offspring seedlings during the summer flowering period). As the diameter level of the mother tree increases, the germination rate, germination index, and vitality index of seeds during the spring flowering period first increase and then decrease, with the highest values observed at a ground diameter of 10.0-19.9cm. However, the above indicators of summer flowering seeds gradually decreased with the diameter increasing. There were significant differences in salt tolerance of seeds during different flowering periods. The germination rate and germination index of spring flowering seeds significantly decreased between 11‰ and 15‰, but the effect of salt concentration on summer flowering seed germination was not significant. For the early growth of seedlings, as the salt concentration increased, the root length and seedling height of seed offspring seedlings during spring and summer flowering periods decreased after being higher than 5‰. Compared with spring flowering seeds, summer flowering seeds had higher germination ability and seedling weight under salt stress. Therefore, the salt tolerance of the seeds of <i>T. austromongolica</i> was determined by the size of the mother tree and the flowering period, which is an important strategy for its adaptation to the Yellow River Delta region.

Kinetics of hydrate formation by CO2 and mixture of CO2–C3H8 in concentrated NaCl solution: Effect of impellers

Hydrate-based desalination (HBD) can apply directly to high-salinity water produced with crude oils and gases. For HBD technology to be commercialized, the slow kinetics of hydrate formation must be overcome. This study investigates the effects of type, diameter, number and clearance of impellers on kinetics, i.e. nucleation and growth, of hydrates of pure CO2 and mixture of CO2–C3H8 in a stirred vessel. Concentrated saline solution (8 wt%) was applied to form hydrates at constant temperatures (271.15–279.15 K) and pressures (1.73–3.6 MPa). Single pitched blade (PB) and straight blade (SB) impellers and also dual combinations of them were applied. With both SB and PB impellers at single mode, lower clearance improved nucleation rates (lower induction times) and higher clearance improved growth rates. The growth rate with SB was higher than that with PB under similar conditions, showing that radial flow is in favor of growth rate. With dual combination of PB and SB, higher nucleation and growth rates were observed compared to single impellers. The presence of PB in dual configuration influenced only the nucleation rate. Using a large diameter SB impeller, resulted in higher growth rate and gas consumption in dual mode. The results with CO2–C3H8 mixture were the same as pure CO2. Due to the promoting effect of propane on nucleation and growth rates, the effects of variation in propeller characteristics became minor in the presence of propane.

Effect of Varied NaCl Soaking Treatment on Chemical Composition of Lesser Yam Flour and Its Use in the Production of Gluten-Free Noodles

In order to reduce dependence on wheat flour, it was necessary to use alternative options, such as lesser yam flour. The production of lesser yam flour consisted of soaking yam tubers in NaCl solutions of different concentrations (20% and 25%). This soaking process was necessary for enhancing the physical characteristics of the flour, resulting in reduced mucus and a whiter appearance. The diverse NaCl concentrations during soaking significantly affected chemical composition of lesser yam flour, impacting parameters, including moisture, ash, fat, total protein, reducing sugar, total sugar, glucomannan content, and calories. However, no discernible effect was observed on the crude fiber and carbohydrate content. In comparison to the 25% NaCl, the 20% NaCl had lesser yam flour with lower moisture, ash, protein, total sugar, and reducing sugar content, but higher fat, glucomannan, and calories. The 25% NaCl soaked lesser yam flour was selected for the production of gluten-free dry noodles. Dry noodles were prepared with various proportions of lesser yam flour and mocaf flour, including 0:100 (TG0), 50:50 (TG1), 50:40 (TG2), 70:30 (TG3), 80:20 (TG4), and 90:10 (TG5). An increase in the proportions of lesser yam flour resulted in increased hardness and chewiness, along with decreased springiness and cohesiveness. Therefore, lesser yam could be processed into flour by soaking in NaCl solutions to produce better flour, with the optimal flour composition being 80% lesser yam flour and 20% mocaf flour for gluten-free noodles production. This suggested the potential for further development of lesser yam flour as a raw material for the production of gluten-free noodles.

Mathematical modeling of the transport characteristics of a PVDF-based cation-exchange membrane with low water content

New effective ion-exchange membranes are needed for a variety of applications, with a particularly pressing need for membranes used in fuel cells and membrane water electrolysis. PVDF-based membranes are promising for these and other applications. Two samples of such membranes with a low water content are studied. The interest in the behavior of these samples is that with an increase in the bathing NaCl solution concentration, the diffusion permeability decreases, whereas usually it increases along with increasing membrane conductivity. The hypothesis is that with increasing concentration, the water content decreases even more, which leads to a narrowing of the intercluster ion-conducting channels and a reduction in the effective mobility of coions, since the latter have to go around narrowed sections of channels. To simulate the concentration dependence of conductivity, diffusion permeability and transport numbers for the two above samples, the microheterogeneous model is extended to describe the loss of water with increasing external concentration and take into account the decrease of coion percolation through the membrane. The results of simulation are compared with the experimental data.