NaCl Solutions Of Different Concentrations Research Articles

Physico-chemical properties of persimmon leaves brined in varying concentrations of sodium chloride

ABSTRACT Persimmon (Diospyros kaki) leaves contain several bioactive components that have beneficial effects on human health. However, the leaves are mainly consumed in low quantities, as tea and food additives. To increase the intake of persimmon leaves, it is necessary to diversify their processing and preservation methods. This study assessed the effects of different sodium chloride (NaCl) concentrations on the physicochemical properties of brined persimmon leaves. Young leaves of the astringent persimmon trees were harvested, brined in NaCl solutions of different concentrations (1, 5, 10, 15, and 25%), and kept for 30 days at 10°C. A small decrease in the -a* and h° values (more green color) and chlorophyll (a and b) content of the brined persimmon leaves was observed with increasing concentration of the NaCl solutions. Furthermore, with increasing NaCl concentrations, an increase in the salinity, reducing sugars, and phenolic compounds of the brined leaves, as well as the clarity of the brine solutions was observed. The pH, vitamin C content, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity decreased with increasing concentration. The results suggested that brining affected the properties of the persimmon leaves, and higher NaCl concentrations could help to maintain a more intense green color.

Data-Driven Life Modeling of Electrochemical Migration on Printed Circuit Boards Under Soluble Salt Contamination

Under the air pollution environment, the dust enters the electronic products and deposits on the printed circuit boards (PCB) during the service life. Soluble salts in the airborne dust can reduce the critical humidity and increase the ion concentrations on condensed water film on PCB, which has been proven to aggravate the insulation failure of the high-density PCB caused by electrochemical migration (ECM). It is practical application significance for how to establish a life model to evaluate the ECM of PCB under the interaction of soluble salt with temperature, relative humidity, and electric field strength. In this article, through the temperature humidity bias acceleration experiment, the ECM failure of PCB under the contamination of the different concentrations of NaCl solution is simulated, and the ECM characteristics and failure mechanism are studied through the change of surface insulation resistance (SIR) and the morphology and element compositions of migration products. The time to the insulation failure of PCB under different conditions are obtained by the analysis of SIR curves. Based on the data-driven method, the life modeling of ECM failure of PCB under soluble salt contamination is studied by multivariate non-linear regression and machine learning methods, such as support vector regression, gradient boost regression tree, and random forest regression. It is proved that it is valid to use machine learning to establish the ECM failure life model of PCB in complex environments with limited life data.

Research on the Corrosion Behavior of 14Cr12Ni3Mo2VN Stainless Steel in Different Concentrations of NaCl Solution

Research on the Corrosion Behavior of 14Cr12Ni3Mo2VN Stainless Steel in Different Concentrations of NaCl Solution

Insulation Failure Mechanism of Immersion Silver Finished Printed Circuit Board Under NaCl Solution

Various kinds of contaminants depositing on printed circuit board (PCB) assembly in electronic products, such as the airborne dust and the process residues, can aggravate the condensation on the PCB surface and increase the ion concentration of the water film on the PCB, which further degrades the insulation of the PCB based on electrochemical migration (ECM). This paper investigates the insulation failure mechanism of immersion silver (ImAg) finished PCB under sodium chloride (NaCl) solution. A Y-pattern PCB was adopted to simulate the ECM failure of the PCB under different concentrations of NaCl solution by water drop tests. Through the on-line monitoring of the surface insulation resistance of PCB, as well as the dendrite morphology and the compositions detection at different reaction stages and different locations between two parallel electrodes, the similarities and differences of the insulation failure characteristics and mechanism of ImAg finished PCB under various concentrations of NaCl solution were analyzed. The effect of chloridion on ECM was discussed by combining the electrochemical theory.

Irrigation with magnetically treated saline water influences the growth and photosynthetic capability of Vitis vinifera L. seedlings

Salinity is one of the major environmental stresses that can inhibit plant growth and development and cause physiological and metabolic changes. In this study, a pot experiment was performed involving two-year-old grape seedlings. Three different concentrations of NaCl solutions composed of tap water were used to irrigate the potted grapevine in the presence and absence of a magnetic device. The growth parameters and photosynthesis characteristics were analyzed during the stress treatments under field conditions. The results were as follows: Compared with those of the plants irrigated with non-magnetized saline water (NMSW), the growth of the aboveground parts (growth quantity, internode length, basal diameter, leaf area and leaf number) and the root growth (total root length, surface area, mean diameter, volume and root tip number) of plants irrigated with magnetized saline water (MSW) increased in response to the different treatment solutions, and the biomass of the leaves, stems and roots increased by 2.0 %∼45.0 %. The proportion of material allocated to the leaves and roots increased, and the root/crown ratio increased when exposed to 6.0 g·L−1 NaCl solutions. Compared with those in the plants irrigated with NMSW, the chlorophyll a, chlorophyll b and carotenoid contents in the plants irrigated with MSW increased by 3.0 %∼13.0 %. Moreover, compared with NMSW, MSW led to increases in the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), limiting value of stomata (Ls) and water-use efficiency (WUE), while the intercellular CO2 concentration (Ci) decreased. The ratio of specific activity parameters per unit area exhibited the largest increase (from 12.0 % to 26.0 %), and photosynthetic performance indexes increased by 18.0 %–56.0 %. Generally, the abovementioned results indicate alleviated inhibition of grape growth under irrigation with MSW. Moreover, treatment with MSW reduced the damage of saline water to the photosynthetic mechanism in grapevine, helped maintain the photosynthetic activity in the mesophyll cells, and promoted efficient electron transport between the photosystems, thus promoting the biomass production of the grapevine.

Frumkin correction of corrosion electric field generated by 921A-B10 galvanic couple

In order to study the Frumkin correction effect of corrosion electric field generated by 921A-B10 galvanic couple in different concentrations of NaCl solution, the electric double layer (EDL) capacitance of 921A steel and B10 copper alloy at the galvanic potential was acquired by electrochemical impedance spectroscopy (EIS), which was calculated for the experimental value of diffuse layer potential. The theoretical value of diffuse layer potential was got by the theoretical relationship between the diffuse layer potential and the total potential difference of EDL and concentration of supporting electrolyte. According to the Frumkin correction theory, the modified Tafel equation related to diffuse layer potential was obtained. Furthermore, the uncorrected and corrected Tafel equation was used as the boundary condition of the boundary element model (BEM) of corrosion electric field for 921A-B10 galvanic couple, thus the corrosion electric field distribution before and after Frumkin correction was obtained and compared with the experimental results. The results show that the correction effect is 35.6% and 8.8% when the concentration of NaCl is 0.012 M and 0.6 M, respectively. Therefore, it is necessary to correct the Tafel boundary condition during simulation, especially under low electrolyte concentration. The Frumkin correction can greatly reduce the error between results of simulation and experiment.

Effect of NaCl-SDS compound solution on the wettability and functional groups of coal

In order to enhance the wetting performance of surfactants to coal dust and reduce the harm caused by coal dust, different concentration of NaCl solution was added to the anionic surfactant of Sodium Dodecyl Sulfate (SDS). The effect of NaCl-SDS compound solution on wetting coal was studied by DSA25 optical droplet morphology analysis system and Fourier transform infrared spectroscopy (FTIR). The results show that the surface tension and contact angle decrease significantly with the increase of NaCl concentration in SDS. When the concentration of NaCl is 0.9 mol/L, the surface tension and contact angle are the lowest, which are 29.41 mN/m and 29.3°, respectively. In addition, adding NaCl to SDS can change the content of functional groups in coal, in which the content of methyl (CH3) increases with the increase of NaCl concentration. The effect of CH3 content on the contact angle is the most significant, and the contact angle decreases with the increase of CH3 content. The addition of NaCl into SDS can effectively reduce the surface tension of the solution, reduce the contact angle between the solution and the coal sample, and improve the wetting effect. In this paper, a new compound solution is prepared by combining a surfactant and an inorganic salt, and the NaCl-SDS compound solution can further improve the wettability of the surfactant, and is of great significance in reducing the coal dust in the mining process of the coal mine.

Application of the Diffused Double Layer Theory to Nanobubbles.

Nanobubbles have electrically charged interfaces; hence, the diffused double layer theory can be applied to explain the behavior of nanobubbles in different electrolytic solutions. In this research, oxygen nanobubbles were generated in NaCl solutions of different concentrations, and bubble size and ζ potentials were measured just after the generation and after 1 week. The measured data and diffused double layer theory were used to compute the surface charge density, the potential due to the surface charge, and the interaction energy between bubbles. With the increased NaCl concentration, bubble size, surface charge density, and the number of negative charges increased, while the magnitude of ζ potential/surface potential, double layer thickness, internal pressure, and the electrostatic repulsion force decreased. The same trend was observed after 1 week. The net total energy calculation for the 0.001 M NaCl solution showed that the bubble repulsion for an intermediate separation distance had a 6.99 × 10-20 J energy barrier, which prevented bubble coalescence. Hence, the 0.001 M NaCl solution produced stable nanobubbles. The calculation of internal pressure inside nanobubbles showed a reduction in the interfacial pressure difference with the increased NaCl concentration. The test results, as well as diffuse double layer and net total energy calculations, showed that the most stable bubbles were obtained with 0.001 M NaCl concentration and the least stability was recorded with the highest amount (0.1 M) of NaCl concentration.

Modelling of anion-exchange membrane transport properties with taking into account the change in exchange capacity and swelling when varying bathing solution concentration and pH

In this paper we take into account the variation of anion-exchange membrane swelling and effective exchange capacity with changing the concentration and/or pH of the bathing solution when simulating membrane transport characteristics (the electric conductivity, diffusion permeability and ion transport numbers). Two main structural elements of the membrane are distinguished: a microporous polyelectrolyte gel assumed homogeneous, and macropores including structural defects and voids. It is supposed that only microporous gel exerts osmotic pressure, which causes membrane swelling described in our model by the Gregor equation, which employs the mole fractions of free and bound water. Three types of ion-exchange functional groups, namely, the secondary, tertiary and quaternary amino groups are taken into account. The degree of dissociation of these groups depends on the internal solution pH, which is described by equilibriums between protonated and deprotonated forms. The Donnan equations and electroneutrality condition are used to calculate the ion concentration in the membrane. The microheterogeneous model based on the Nernst-Planck equations is used to describe the ion transport. We take into account that the ion diffusion coefficients depend on the degree of gel swelling, this dependence is described by the Mackie-Meares equation. The model parameters include the equivalent volume of dry polyelectrolyte gel, the volume fraction of macropores, the structural parameters and others.The results of calculations are compared with experimental data on the electric conductivity, diffusion permeability and ion transport numbers for two heterogeneous anion-exchange membranes MA-40 and MA-41 (Shchekinoazot, Russia) differed by the fractions of the weakly basic functional groups. A good quantitative agreement between the theory and experiment is found for both membranes using the same set of ion hydration numbers and chemical equilibrium constants for secondary and tertiary amino groups. In particular, it is shown that with increasing pH of the bathing solution, the membrane diffusion permeability passes through a maximum, which is explained by the corresponding maximum of water content. A higher water content results in larger membrane pores, which leads to higher values of ion diffusion coefficients and higher amount of sorbed electrolyte. Together with varying water content, the variation in membrane effective exchange capacity as a function of external solution pH, determines a non-trivial behavior of electric conductivity, diffusion permeability and ion transport numbers in the membrane equilibrated with NaCl solutions of different concentration and pH.

Membrane compaction in forward osmosis process

Membrane compaction is commonly observed in polymeric membranes when subjected to elevated hydraulic pressure, but was rarely discussed in forward osmosis (FO) processes, since there was usually little hydraulic pressure difference across the membrane. In the current study, three TFC membranes were fabricated using hollow fiber substrates with varied water permeability to study the effect of the osmotic pressure on the TFC membranes. The TFC membranes were continuously tested in FO experiments for 24 h by using DI water as feed and NaCl solutions of different concentrations as draw solution, and their performances were checked again using fresh feed solutions. At the end of FO experiments, all TFC membranes experienced water flux and salt flux decline to different extents. The TFC membranes were characterized using SEM, TEM and AFM. Visible changes in the cross-section morphology and surface topography of the TFC membranes were observed after FO experiments. The observation suggested that the occurrence of membrane compaction could be associated with “negative pressure” build-up within the support layer of the TFC membranes. The current study could shed light on the important factors that should be considered during membrane fabrication and when establishing the testing protocols for the characterization of FO membrane.

Effects of NaCl solution on the swelling and shrinkage behavior of compacted bentonite under one-dimensional conditions

Because of its low hydraulic conductivity, high swelling capacity, and good adsorption properties, Gaomiaozi (GMZ) bentonite has been proposed as a suitable buffer/backfill material for construction of artificial barriers in deep geological repositories for high-level nuclear waste (HLW) disposal in China. By varying the concentration of NaCl solution and total suction, the swelling and shrinkage characteristics of compacted GMZ bentonite were studied under one-dimensional conditions. Results show that the swelling strain of compacted GMZ bentonite decreases as the concentration of NaCl solution increases under one-dimensional conditions. During drying with suction control by vapor phase technique, the density increases with suction. Simultaneously, the sample saturated with salt solution has a larger void ratio than that of the sample saturated with distilled water under the same suction. The void ratio and water content of the samples decrease with increasing suction. For a given suction, the sample saturated with salt solution has a higher degree of saturation than the sample saturated with distilled water. With the obtained water content (w), void ratio (e), and the degree of saturation (Sr), soil-water retention curves (SWRCs) were calculated for samples initially hydrated with different concentrations of NaCl solution. The SWRCs reveal that the sample with salt solution has higher water retention capacity than the sample with distilled water. A modified SWRC equation was proposed to account for the effect of NaCl solutions on the drying process of compacted GMZ bentonite under one-dimensional conditions. The results confirm that the modified SWRC equation can effectively describe the SWRCs of compacted GMZ bentonite considering the effects of NaCl solutions.

Investigation of corrosion rate on the modified 410 martensitic stainless steel in tempered condition

Martensitic stainless steels were usually used for turbine blade. Their properties can be improved in various ways, such as by heat treatment. This paper reports the influences of tempering temperature and holding time in various concentration and temperature of NaCl solution on corrosion rate of the modified 13Cr martensitic stainless steels. Samples were austenized at 1050°C for 1 hour followed by oil quenching. The austenized sample were tempered at 600°C, 650°C, and 700°C for 1, 3, and 6 hours. All tempered specimens were immersed in 20% NaCl concentration for 120 hours and tempered specimen at 700°C for 6h was prepared for another corrosion test. Samples were immersed in different concentration of NaCl solution 3.5%; 10%; and 20% at room temperature, 60°C, and 80°C. Increasing temperature and concentration of solution will lead to corrosion rate increased. However, corrosion rate slightly decreases at higher temperature due to dissolved oxygen was decreased.

Analysis of Chloride Ion Sensor Modified by Graphene Oxide Under Microfluid Flow

In this paper, we used a thermal evaporation system and a radio-frequency sputtering system to fabricate aluminum (Al) electrodes and indium–gallium–zinc oxide (IGZO) sensing membranes on the polyethylene terephthalate substrate. The IGZO/Al chloride ion sensor modified by graphene oxide has array sensing windows to avoid sensor malfunction. We used a screen printing technology to fabricate the sensor that made sensor a flexible structure. It can be adapted to many environments. The chloride ion sensor was immersed in the different concentrations of NaCl solutions from $10^{-5}$ to 1 M to measure the sensing characteristics of the chloride ion sensor. From the static measurement, the average sensitivity and linearity of the chlorine ion sensor were 60.536 mV/pCl and 0.973, respectively. We integrated microfluidic framework to measure the dynamic characteristic. From the dynamic measurement, we could know that the best average sensitivity and linearity of the chloride ion sensor for the flow rate of $20~\mu \text{L}$ /min were 64.639 mV/pCl and 0.972, respectively. To confirm the non-ideal effect of chloride ion, the hysteresis voltages of chloride ion in the different concentrations of NaCl solutions in two different cycles were 2.700 and 2.789 mV, respectively.

Peak shear strength of compacted GMZ bentonites in saline solution

Knowledge of the peak shear strength of compacted bentonites is of fundamental importance to high-level nuclear waste repositories, as it forms the basis of the analysis of repository stability. The shear strength properties of GMZ bentonites are throughout investigated by undrained direct shear tests with different concentrations of NaCl solutions, and are explained in the light of the modified effective stress concept, which takes into consideration of the osmotic suction. The modified effective stress concept is expressed as p’ = p + π(p/π)Ds-2, incorporated with the normal stress (p) and osmotic suction (π) based on the bentonite surface fractal model. The peak shear strength behavior of GMZ bentonites in NaCl solutions appears to be explained satisfactorily by the modified effective stress. According to the Mohr-Coulomb criterion, the peak shear strength of bentonites saturated by distilled water and NaCl solutions is expressed by the same unique line in the τ-p’ plane. GMZ bentonite has the same values of the peak friction angle and the peak cohesion in distilled water and NaCl solutions of different concentrations.

Separation of CH4/N2 of Low Concentrations From Coal Bed Gas by Sodium-Modified Clinoptilolite.

Clinoptilolite is a widely distributed tectosilicate, mainly composed of Al2O3, SiO2 with exchangeable cations such as Ca, K, Mg, and Na. In this research, raw clinoptilolite was ground, gravimetrically concentrated and ion-exchanged using different concentrations of NaCl solution. Then the modified clinoptilolite powder was formulated into particles as adsorbents. The adsorbents were applied to CH4 separation in coal bed gas. The raw and modified clinoptilolites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), atomic emission spectrometer (ICP-AES), Fourier transform infrared spectrometer (FTIR), and Brunauer Emmett Teller (BET) specific surface area. The CH4 absorptivity by raw and modified clinoptilolites was evaluated using pressure swing adsorption (PSA) to assess the CH4 separation ability. The results indicated that the ion-exchanged clinoptilolite using 0.2 mol/L NaCl solution was found to be promising for the kinetic PSA separation of CH4/N2, giving a better absorptivity for CH4 separation under different influence factors. Based on the simulated static experiments, it was indicated that both CH4 and N2 were capable of diffusing into clinoptilolite while N2 adsorption by clinoptilolite was excellent. The experiment results also indicated that ion-exchanged clinoptilolite using a 0.2 mol/L NaCl solution was the optimal adsorbent for separating CH4/N2 at the low pressure condition. From the simulated dynamic experiments, the ion-exchanged clinoptilolite using a 0.2 mol/L NaCl solution as a potential sorbent in kinetic PSA processes for N2/CH4 separation, exhibited the best performance at 648 K under 0.2 MPa within 28 min, in comparison to the raw clinoptilolite and clinoptilolite under other modification conditions. In the next phase of research, the modified clinoptilolite will be tested for CH4 separation in real coal bed gas.

Random phase-shift Bragg grating-based random fiber laser with a half-open cavity.

A random fiber laser based on a 25mm long random phase-shift fiber Bragg grating with a half-open cavity is experimentally demonstrated in this paper. The random phase-shift grating is fabricated in single-mode fiber with the beam-scanning method. The random feedback and light localization are achieved by introducing 20 phase shifts with random amplitudes along the grating length. Different couplers and different directions are adopted to investigate the output characteristics under multiple conditions. The stable single-wavelength laser operation with the pump threshold of only 25mW is realized using a 980nm pump laser. The optical signal-to-noise ratio up to 67dB and the 3dB bandwidth of 17.7pm are obtained at the pump power of 350mW. It is found that the emitted wavelength varies linearly with the surrounding refractive index within a certain range by immersing the grating in different concentrations of NaCl solutions, which provides a potential method for lasing wavelength tuning and refractive index detection.

Probing the Effect of Salt on Asphaltene Aggregation in Aqueous Solutions Using Molecular Dynamics Simulations

The presence of salts in different processes of oil production has attracted wide attention because of its effects on asphaltene aggregation, stability, interactions of emulsions, etc. In this work, molecular dynamics simulations were employed to study the effect of salts on aggregation of model asphaltenes. Four types of polyaromatic compounds possessing key structural features of continental-type asphaltenes were dispersed into NaCl solutions of different concentrations. These models have the same polyaromatic core but different lengths for the side chains. In the two models with relatively long side chains, the hydrophobic association among side chains is the main driving force for aggregation. The effect of salt on aggregation is therefore closely tied to its influence on the hydrophobic interaction: the salt ions promote the hydrophobic interaction at a low salt concentration while suppressing it at a high salt concentration. For the model with an intermediate side chain length, the hydrophobic interaction between side chains becomes less dominant and the salt has mutual influences on the core–core, chain–chain, and core–chain interactions. For the model with the shortest side chains, although the core–core and core–chain interactions are more important, the side chains still play a role in aggregation when the salt is present. Our results provide new insights into the fundamental understanding of the influence of salts on the aggregation and interaction behaviors of polyaromatic compounds in an aqueous environment.

Improvement of the electrical disintegration of coal sample with different concentrations of NaCl solution

The application of high-voltage electrical pulse (HVEP) technology to the improvement of pore structure of coal has achieved encouraging results. However, the very high breakdown voltage of some kinds of coal seriously affects the application of HVEP technology. In this study, the relationship between the concentration of NaCl solution and the breakdown voltage of coal sample was studied by improving the electrical breakdown effects of Linhua anthracite coal and Hongliu bituminous coal with different concentrations of NaCl solution, and a negative exponential relationship was established. The results indicate that the breakdown voltages of coal samples decrease with the increase of the concentration of NaCl solution, but there is a limit to the magnitude of the decrease. Additionally, nuclear magnetic resonance (NMR) and X-ray photoelectron spectrometer (XPS) were adopted in this study to investigate variations in pore structure and functional groups before and after the electrical breakdown. The NMR analysis demonstrates that the electrical breakdown mainly improves the number of mesopores and macropores and enhances the connectivity between them, thus providing a smoother channel for gas extraction. The XPS analysis reveals that a new oxidation reaction appears where the current flows through, which promotes gas desorption from surfaces of coal samples.

A Sensitive and Stable Surface Plasmon Resonance Sensor Based on Monolayer Protected Silver Film.

In this paper, we present a stable silver-based surface plasmon resonance (SPR) sensor using a self-assembled monolayer (SAM) as a protection layer and investigated its efficiency in water and 0.01 M phosphate buffered saline (PBS). By simulation, silver-based SPR sensor has a better performance in field enhancement and penetration depth than that of a gold-based SPR sensor, which are 5 and 1.4 times, respectively. To overcome the instability of the bare silver film and investigate the efficiency of the protected layer, the SAM of 11-mercapto-1-undecanol (MUD) was used as a protection layer. Stability experiment results show that the protected silver film exhibited excellent stability either in pure water or 0.01 M PBS buffer. The sensitivity of the silver-based SPR sensor was calculated to be 127.26 deg/RIU (refractive index unit), measured with different concentrations of NaCl solutions. Further, a very high refractive resolution for the silver-based SPR sensor was found to be 2.207 × 10−7 RIU, which reaches the theoretical limit in the wavelength of 632.8 nm for a SPR sensor reported in the literature. Using a mixed SAM of 16-mercaptohexadecanoic acid (MHDA) and a MUD layer with a ratio of 1:10, this immunosensor for the rabbit immunoglobulin G (IgG) molecule with a limit of detection as low as 22.516 ng/mL was achieved.

Estimation of ice formation in mortar saturated with sodium chloride solutions

Frost damage of concrete is usually caused by ice expansion, therefore, the ice formation of NaCl solutions is of significant importance for predicting the mechanical degradation of concrete under the combined frost action and NaCl attack. In this study, the ice formation in cementitious materials saturated with different concentrations of NaCl solution is theoretically investigated first. Then the ice formation in mortar is further studied experimentally by electrical measurements. To estimate the ice amount based on the electrical measurements, the relationship between temperature, saturation degree, solution concentration and the electrical conductivity of mortar specimen is clarified. With regard to ice formation and salt crystallization during freeze-thaw, the ice content estimation model is proposed for mortar specimens. In addition, electrical response of meso-scale mortar specimens saturated with NaCl solutions with freeze-thaw cycles (FTCs) is measured. The electrical test results are interpreted with the proposed model and the ice formation is estimated with FTCs. The results from electrical measurements are compared with the theoretical calculations, and acceptable agreement is observed.