Diffusion Coefficient Of NaCl Research Articles

Cation–polymer interactions and local heterogeneity determine the relative order of alkali cation diffusion coefficients in PEGDA hydrogels

Current research efforts are focused on endowing polymer membranes with ion–ion selectivity by incorporating ion–polymer interactions into materials to bias the selective partitioning and or diffusivity of one species over another. However, little is known about the impact of such interactions on the mechanisms of ion transport. In this study, we probe the influence of cation–polymer interactions on cation, anion, and salt diffusivity in a model membrane material, poly(ethylene glycol) diacrylate (PEGDA) by modeling concentrated polyethylene oxide solutions via molecular dynamics simulations. These results are compared to published experimental data for LiCl, NaCl, and KCl diffusion in PEGDA. Experimentally, the order of salt and cation diffusion coefficients for LiCl, NaCl, and KCl deviate from the order in aqueous solutions. Simulations identify these deviations to arise from cation–polymer coordination in the membrane. Both the fraction of bound cations and the average binding lifetime increases with decreasing cation hydration free energy (moving down the alkali series), leading to different diffusivity trends in the membrane compared to solution. However, to recover the experimentally observed order of diffusivities cations and salt in our simulations, we needed to incorporate membrane heterogeneity explicitly via a polymer charge scaling procedure. Together, our results indicate that cation–polymer interactions, as well as spatial heterogeneity within the membrane, play a critical role in dictating the observed order of alkali cation and salt diffusion coefficients in membranes.

Simulation Study of Xylitol-Mediated Effect on NaCl Diffusion Behavior in Cured Pork Tenderloin.

Polyhydroxy alcohol-mediated curing has great potential for producing low-salt cured meat products. This study investigated the mass transfer kinetics and the one-way diffusion simulation of sodium chloride (NaCl) during the curing process. Furthermore, Fick's second law determined the NaCl diffusion coefficient (De) of xylitol-mediated cured pork tenderloin. The results demonstrated that adding xylitol could reduce the De of NaCl. The De of NaCl, calculated using the one-way model, was 1.29 × 10-9 m2·s-1, 1.22 × 10-9 m2·s-1, 1.2 × 10-9 m2·s-1, and 1.15 × 10-9 m2·s-1 when the amount of xylitol added was 0%, 4%, 8%, and 12% (w/w), respectively. This result agrees with the predicted values from the power function time-varying model. Moreover, a three-dimensional simulating model of mass transfers constructed using COMSOL Multiphysics was developed to evaluate the NaCl diffusion in pork tenderloin during the curing process. This model has high accuracy and can be used to describe the diffusion of NaCl in curing. Overall, this study provided a foundation for NaCl diffusion and distribution during the curing process.

Change in rapid salting kinetics and characteristics of hen egg yolks

A study of the dynamics of egg yolk salting clarified the diffusion of salt and the resulting changes in yolk quality and thereby provided guidance for better control of the final product. The effects of different salt contents in the salting solution (between 16 and 24%) on the mass transfer kinetics and egg yolk quality were analyzed during rapid salting. The results for the egg yolks showed that the changes in weight and water concentration decreased with increasing salt mass fraction, while the NaCl change increased. An increase in the salt content in the salting solution increased the effective diffusion coefficient ( D e ) of NaCl. Low-frequency nuclear magnetic resonance (LF-NMR) spectroscopy showed that higher salt content in the solution improved the amount of water transferred. The salted egg yolks treated in the 20–24% salting solutions had higher hardness, cohesiveness, oil yield and sandiness than those treated in other salting solutions. The samples salted in 16% solution had the highest values of the egg yolk index and CIELAB colorspace dimensions a* and b*. An analysis revealed statistically significant correlations between oil yield, sandiness, texture and color with D e . Taking oil yield and sandiness as the main indexes and comprehensively considering other sensory characteristics showed that 20% NaCl was the most suitable salt water solution for the rapid salting of hen egg yolks. ● The mass transfer and quality change of egg yolks increased with the salt content. ● The effective diffusion coefficient ( D e ) increased with salt content from 20 to 24%. ● T 23 , egg yolk index, springiness, cohesiveness, a* and b* decreased with salt content. ● T 22 , oil yield, sandiness, hardness, chewiness and L* increased with salt content. ● Oil yield, sandiness, texture and color were significantly correlated with the D e .

Empirical indication for desalinating properties of porous boron nitride

In recent years, inorganic 2D materials have been recognized as promising candidates for membrane filtration. In particular, theoretical studies predict the excellent desalination performance of nanoporous hexagonal boron nitride. However, studies showing the experimental realization of such systems are to this date missing. In this work, we demonstrate the desalinating properties of sp2-bonded boron nitride. Secondary Ion Mass Spectrometry experiments have shown the clear separation of NaCl and water by the boron nitride film: Na and Cl ions have been retained and trapped in the near-surface region, while water permeated through its whole depth. Analysis based on the diffusion equation revealed that the diffusion coefficient of water is over 3 orders of magnitude higher than the diffusion coefficient of NaCl in the temperature range of 25-65°C, manifesting that boron nitride is a material of high potential for use as a selective layer for membrane filtration.

Influence of ultrasound-assisted tumbling on NaCl transport and the quality of pork

The present study aimed to investigate the impact of ultrasound-assisted tumbling (UAT; 20 kHz, 100, 300, 500 and 700 W) with different treatment time (30, 60, 90 and 120 min) on the diffusion and distribution of NaCl as well as the change of pork texture properties during curing. Results showed that in comparison with the single tumbling (ST), the NaCl content and the NaCl diffusion coefficient were increased along with UAT treatment (P < 0.05). The scanning electron microscopy and the energy dispersive X-ray analysis showed that UAT treatment changed the microstructure of pork which may facilitate the NaCl dispersion homogeneously. In addition, the moderate UAT treatment of 300 W with 60 min could significantly improve the tumbling yield, water-holding capacity and textural properties of pork compared with the ST treatment (P < 0.05). Meanwhile, in comparison with the ST group, protein extraction was considerably increased after UAT (300 and 500 W) treated for 120 min (P < 0.05). Our study demonstrated that UAT treatment could effectively promote the penetration and distribution of NaCl and improve pork meat quality via facilitating the extraction of meat protein.

Modeling the NaCl diffusion in beef during brining process.

An in-depth understanding of mass transfer during brining process is important for improving the quality and characteristics of meat products. In this study, a fitted equation of time and NaCl concentrations in the aqueous phase of beef was established to calculate the NaCl diffusion coefficient for simulation. A three-dimensional simulating model of mass transfer was developed to evaluate the NaCl diffusion in beef during brining process. And the validity of this simulating model was verified by comparing the NaCl concentrations evaluated by the numerical simulation simulated with the experimental measurements. The results indicated that the power function time variant equation can predict NaCl concentrations (R2 = 0.995) and accurately calculate the NaCl diffusion coefficient (8.46×10-10 m2 /s). The simulating model visually showed the NaCl diffusion in beef during brining process. Therefore, this research provided a new method for predicting the NaCl diffusion in realistic meat processing. PRACTICAL APPLICATION: This research gives a new method for predicting the NaCl diffusion in meat product. The method accurately evaluated NaCl concentrations in beef at different brining time and clearly showed NaCl diffusion in beef during brining process, which could be helpful in reducing the cost and the complexity of detecting NaCl concentrations in meat during brining process.

Effect of ultrasonic‐assisted brining on mass transfer of beef

AbstractThe objective of this study was to evaluate the effect of ultrasonic intensity (7.5, 10.0, and 12.7 W/cm2) and treatment time (10, 20, and 30 min) on mass transfer of beef during brining process. Changes in the salt and moisture contents in brined beef showed that ultrasound treatment had a positive effect on the mass transfer during brining process. The high correlation between the weight changes of beef and treatment time indicated that the mass transfer kinetics model could be used to evaluate the weight changes of beef during ultrasonic‐assisted brining process. The increase of NaCl diffusion coefficients calculated by the Fick's second law suggested that ultrasound treatment could accelerate the NaCl diffusion into beef (p &lt; .05). The binarized images visualized the increments of NaCl solution in beef by ultrasonic‐assisted brining. These results provided a basis for the ultrasound application in rapid brining of meat products.Practical applicationsUltrasound as a novel and promising technology has some potential advantages in meat processing. This research showed that ultrasound treatment could contribute to the mass transfer during brining processing, and enhanced the NaCl diffusion into beef. The binarized images visualized the quantity of NaCl solution in beef treated with ultrasound. Therefore, ultrasound could be considered as an effective method to accelerate the brining process of meat products.

Chitosan/graphene oxide mixed matrix membrane with enhanced water permeability for high-salinity water desalination by pervaporation

Pervaporation is a promising technology for water desalination. In this work, graphene oxide (GO) was incorporated into chitosan (CS) to fabricate mixed matrix membranes (MMMs) to explore the enhancement of water permeability for high-salinity water desalination and to understand the transport mechanism in the MMMs. The effect of GO content on the morphology, wettability and desalination performance of the membranes as well as the thermodynamic and kinetic behavior of water and salt permeation in the membranes were investigated. The MMMs have rougher and more hydrophilic surface, dense structure and improved mechanical stability owing to the good chemical compatibility of GO with CS matrix. The apparent activation energy results indicate the advantage of the MMMs in desalinating high-salinity water. The enhanced permeate flux of 30.0 kg/m2·h was obtained in desalinating 5 wt% aqueous NaCl solution at 81 °C with 1 wt% GO content and 99.99% of salt rejection was achieved. The solubility and diffusivity of H2O and NaCl in the MMMs demonstrate a trade-off effect on the water permeability and water/salt selectivity with increasing of GO content. The NaCl diffusion coefficient in the membranes was lower than that of H2O by two orders of magnitude, contributing to the high selectivity of the membrane.

One-directional modelling to assess the mechanistic actions of power ultrasound on NaCl diffusion in pork

A one-directional modelling method for the assessment of the influence of power ultrasound (US) (4–19Wcm−2, 25–40min) on NaCl diffusion in pork is presented. In doing so, the mechanistic actions of US salting in meat are elucidated. Temperature controls (4–21°C) were generated according to each US treatment. NaCl concentration profiles were fitted to Fick’s second law, generating the effective NaCl diffusion coefficient (Dseff). Dseff ranged from 1.34×10−10 to 4.01×10−10m2s−1, which is in agreement with the literature. The average Dseff was higher at increased temperature (p<0.05) and US intensity (p<0.01) and a lower Dseff was found with longer US treatment time as an effect of structural changes in the meat (p<0.05). The Dseff was higher at all US intensities than the corresponding temperature control indicating that mass transfer is accelerated by US mechanisms, such as cavitation, independent of temperature effects. This study provides further information on the mechanistic actions of ultrasonic enhanced mass transfer and further proves the potential of power US for the accelerated salting of pork.

Accounting for frame of reference and thermodynamic non-idealities when calculating salt diffusion coefficients in ion exchange membranes

Accurate evaluation of salt diffusion coefficients from transport rate data in ion exchange membranes requires accounting for frame of reference and non-ideal thermodynamic effects. Due to a lack of models and experimental data quantifying membrane ion activity coefficients, it has been impossible to evaluate the impact of non-ideal thermodynamic effects on observed salt diffusion coefficients. Here, a framework is presented that includes both frame of reference (i.e., convection) and non-ideal thermodynamic effects in calculating salt diffusion coefficients in ion exchange membranes. Effective concentration averaged NaCl diffusion coefficients were determined as a function of upstream NaCl concentration in commercial ion exchange membranes from NaCl permeability and sorption measurements via the solution-diffusion model. Frame of reference effects were evaluated using a version of Fick's law that accounts for convection. The factors necessary to account for non-ideal thermodynamic effects were developed using Manning's counter-ion condensation theory. At low upstream NaCl concentrations, frame of reference and non-ideal thermodynamic effects on diffusion coefficients were negligible. However, at higher upstream NaCl concentrations (e.g., >0.1M), both effects contribute measurably to NaCl diffusion coefficients. Correcting for frame of reference effects increased apparent NaCl diffusion coefficients. However, correcting for thermodynamic non-idealities of the ions sorbed into the membranes reduced apparent NaCl diffusion coefficients. Fortuitously, for the materials considered in this study, frame of reference and non-ideal thermodynamic effects nearly cancel each other.

How NaCl and water content determine water activity during ripening of Gouda cheese, and the predicted effect on inhibition of Listeria monocytogenes

This study describes the diffusion of NaCl and water in Gouda cheese during brining and ripening. Furthermore, we established water activity as a function of the NaCl-in-moisture content in Gouda cheese during ripening. We determined NaCl content, water content, and water activity in block-type Gouda cheeses that were brined for 3.8d and foil-ripened for a period of 26 wk, and in wheel-type Gouda cheeses that were brined for 0.33, 2.1, or 8.9d and subsequently nature-ripened for a period of 26 wk. The calculated diffusion coefficients of NaCl during brining were 3.6·10−10 m2s−1 in the block-type Gouda cheeses and 3.5·10−10 m2s−1 in the wheel-type Gouda cheeses. Immediately after brining, gradients of NaCl and water were observed throughout both types of cheese. During ripening, these gradients disappeared, except for the water gradient in nature-ripened cheeses. An empirical model was derived for Gouda cheese, in which water activity is expressed as a function of the NaCl-in-moisture content, as established for different brining times, locations and ripening times. Moreover, the effect of reduced water activity on inhibition of growth of Listeria monocytogenes in Gouda cheese was calculated. In addition to the presence of lactate and a pH of 5.2 to 5.3, the reduced water activity as seen in Gouda cheese can substantially contribute to inhibition of microbial growth and even to inactivation when cheeses are brined and ripened for extended times and subjected to nature-ripening.

Power ultrasonic on mass transport of beef: Effects of ultrasound intensity and NaCl concentration

Abstract The effects of ultrasound intensity and salt concentration of brining for accelerating brine transfer into beef were evaluated. Samples were analyzed with NaCl and water content, effective diffusion coefficient and microstructure. Results showed that ultrasound intensity and NaCl concentration of brine could significantly affect NaCl and moisture content at different treating time during meat brining (p Industrial relevance In our research, the ultrasound intensity could significantly affect diffusion coefficients (D) of NaCl or water while the salt concentration with ultrasound processing was slightly affected the values of D, these results indicated that in industrial application, we might focus on the effect of ultrasound intensity. In addition, along with the emerging technology, this could reduce the amount of NaCl supplemented in brining and shorten the processing time.

Morphological, Chemical Surface, and Diffusive Transport Characterizations of a Nanoporous Alumina Membrane.

Synthesis of a nanoporous alumina membrane (NPAM) by the two-step anodization method and its morphological and chemical surface characterization by analyzing Scanning Electron Microscopy (SEM) micrographs and X-Ray Photoelectron Spectroscopy (XPS) spectra is reported. Influence of electrical and diffusive effects on the NaCl transport across the membrane nanopores is determined from salt diffusion measurements performed with a wide range of NaCl concentrations, which allows the estimation of characteristic electrochemical membrane parameters such as the NaCl diffusion coefficient and the concentration of fixed charges in the membrane, by using an appropriated model and the membrane geometrical parameters (porosity and pore length). These results indicate a reduction of ~70% in the value of the NaCl diffusion coefficient through the membrane pores with respect to solution. The transport number of ions in the membrane pores (Na+ and Cl−, respectively) were determined from concentration potential measurements, and the effect of concentration-polarization at the membrane surfaces was also considered by comparing concentration potential values obtained with stirred solutions (550 rpm) and without stirring. From both kinds of results, a value higher than 0.05 M NaCl for the feed solution seems to be necessary to neglect the contribution of electrical interactions in the diffusive transport.

THE STUDY ON THE INFLUENCE OF THE ELECTROHYDRAULIC EFFECT ON THE DIFFUSION COEFFICIENT AND THE PENETRATION DEPTH OF SALT INTO MUSCLE TISSUES DURING SALTING

Abstract: Currently, promising methods for intensifying the salting technology of raw meat are those based on pulsed energy effects, accompanied by a variety of physical and chemical effects. One of these methods is a discharge-pulse technology, developed by the scientists of the department of meat and canning technologies of the North Caucasus Federal University. When a short high voltage electrical pulse forms in the brine-meat system, high pressure forms in the working tank, the increase in pressure is accompanied by a set of physical and chemical phenomena, such as ultrasound and electromagnetic radiation, ultraviolet glow, cavitation, etc. Taken together, all these phenomena have a beneficial impact on both the brine and the meat itself, accelerating the process of salting. In the present study, we tried using the method of determining the diffusion coefficient of salt in beef muscle tissues empirically by creating a concentration difference in two communicating chambers, the liquids in which are separated by the studied raw material of a given thickness. The main goal of the work was to evaluate the effectiveness of the discharge-pulse technology of salting meat raw materials by determining the NaCl diffusion coefficient and the penetration depth of salt into meat samples. The experimental results showed that with the discharge-pulse treatment of meat, the penetration rate of salt into muscle tissue increases and is proportional to the number of pulses transmitted to the system. The diffusion coefficient in test samples was higher that in the control meat samples at each time period. Based on the obtained results, we came to the conclusion that the discharge- pulse meat treatment contributes to the intensification of diffusion osmotic processes in the wet salting technology.

Non-equilibrium thermodynamic model for calcium carbonate supersaturated solutions of high salinity

Based on principles of non-equilibrium thermodynamics, the behavior of calcium carbonate supersaturated solutions of high salinity is studied. For this purpose, these solutions are treated as continuous media whose physicochemical properties change in space and time. Furthermore, by exploiting the Muller–Liu formulation for the second law of thermodynamics, one recognizes which thermodynamic forces are responsible for keeping the \(CaCO_{3}\) supersaturated solutions out of equilibrium. The obtained results suggest that intermolecular interaction forces play an important role in the dynamics of solution, as well as in the mass transport of solutes. Particularly, from the estimated values for the self-diffusion and mutual diffusion coefficients of NaCl(aq), \(CaCl_{2}(aq)\), and \(Na_{2}CO_{3}(aq)\), one discusses whether changes in the concentration of NaCl(aq) may affect the mass transport of \(Na_{2}CO_{3}(aq)\) and \(CaCl_{2}(aq)\) in calcium carbonate supersaturated solutions. The results of this work may be helpful to understand better the influence of diffusive processes and intermolecular interaction forces on the dynamics of calcium carbonate supersaturated solutions of high salinity.

Changes in Morphology and Ionic Transport Induced by ALD SiO2 Coating of Nanoporous Alumina Membranes

Nanoporous anodic alumina membranes (NPAMs) were produced by the two-step anodization method in sulphuric, oxalic and phosphoric acidic electrolytes displaying a hexagonally ordered spatial arrangement of pores with well controlled nanopore size distribution and low porosity. Some selected NPAMs were further modified by conformal coating their surface and inner pore walls with a thin layer of SiO2 by means of atomic layer deposition (ALD), which reduces both the pore radii and porosity but it also seems to affect to the electric fixed charge on the membranes surface. A comparative study about the influence of silica modification of NPAMs surfaces on the ionic transport through the nanoporous membranes has been performed by measuring membrane potentials and electrochemical impedance spectroscopy with NaCl solutions. According to these results, a direct correlation between the membrane effective fixed charge and the NaCl diffusion coefficient can be established. The coating with a SiO2 thin layer causes a reduction of 75% in the positive effective fixed charge of the NPAMs independently of their pore radii and the increase in counterion transport (cation transport number and diffusion coefficient) even through constrained nanopores, which can be of interest in several applications (microfluidics, drug delivery, nanofilter devices, etc.). Moreover, slight changes in the membrane/solution interface due to the SiO2 cover layer are also indicated.

The endowment of monovalent selectivity to cation exchange membrane by photo-induced covalent immobilization and self-crosslinking of chitosan

In this work, the monovalent selectivity was successfully endowed to conventional cation exchange membrane by photo-induced covalent immobilization and self-crosslinking of chitosan. The chemical and morphological changes of the membrane surface after modification were examined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Then, some electrodialysis experiments for Na+/Mg2+ system and H+/Zn2+ system which were used to simulate the seawater concentration and the hydrometallurgy applications, respectively, were performed to evaluate the monovalent selectivity of the modified membranes. Subsequently, diffusion experiments of NaCl and current–voltage curve measurement experiments were also conducted to comprehensively estimate membrane properties, such as diffusion coefficient of NaCl, membrane electrical resistance and limiting current density. Moreover, the influences of some further treatments for increasing charging intensity and compactness of the immobilized chitosan layer, including quarternization or/ and crosslinking, on membrane properties, were also investigated and analyzed. These contributed to recognize the dominant factors in selective separation and pave the road for tailoring the modified membranes for some specified applications. Anyway, the experimental results have clearly showed that the modified method put forward in this study was promising due to its facility, low cost and efficiency.

Measurement of small molecule diffusion with an optofluidic silicon chip

In this work we explore the micro-ring resonator platform to study the diffusion-driven mass transport of small molecules within microfluidic channels. The micro-ring resonators are integrated on a silicon-on-insulator photonic chip and combined with microfluidics in poly(dimethylsiloxane) (PDMS). We apply a strong initial gradient in the solute concentration and use the micro-ring resonators to observe how this concentration evolves over time and space. This can be achieved by tracking the optical resonances of multiple micro-rings as they shift with changing solute concentration. Experiments are performed for both glucose and NaCl and at different temperatures. The measured concentration profiles are used to calculate the diffusion coefficient of both glucose and NaCl in water. The good agreement between measurement and theoretical prediction demonstrates the relevance of this method.

Development of phase-shifting interferometry for measurement of isothermal diffusion coefficients in binary solutions

In this study, a phase-shifting interferometer to conduct real-time high-resolution measurements of concentration profiles in binary diffusion fields was developed. The phase-shifting interferometer comprises a Mach–Zehnder interferometer, a rotating polarizer, a CCD camera, and an image-processing unit. A phase-shifting technique was used to determine the phase difference between a test beam and a reference beam by using three images taken at intervals of 1/30s. The phase difference is obtained for a spatial resolution of 640×240. This data is further processed in real-time to visualize the concentration profile inside a diffusion cell. The diffusion coefficient is determined by performing an inverse analysis of the experimental concentration profile. The objective function makes use of a numerical calculation, based on Fick's law, for which the initial experimental concentration profile is taken as initial condition. The diffusion field was formed inside a thermally controlled diffusion cell with optical paths as large as 20mm. This large optical path allows measurements of diffusion fields with concentration differences as narrow as 1mg/ml. In order to validate the measurement method, the concentration dependence of the isothermal diffusion coefficient of NaCl and Sucrose was determined in the dilute region at 25°C, such values being extensively reported in the literature. It was found that our optical system is much faster and accurate than similar optical systems to determine the diffusion coefficients in binary systems.

Measurement of the Molecular Mass Dependence of the Mass Diffusion Coefficient in Protein Aqueous Solutions

This paper reports the measurement of the binary mass diffusion coefficient for proteins with a wide range of molecular size. The diffusion coefficient is obtained by conducting diffusion experiments in the dilute region. Transient concentration profiles were measured by a phase shifting interferometer and subsequently compared with a numerical calculation based on Ficks law to determine the diffusion coefficient. Distilled water was used as solvent in free diffusion experiments conducted at T = (25 ± 1.0)°C. The method was validated by measuring the diffusion coefficient of aqueous NaCl, Sucrose, and BSA, which values have been extensively reported in the literature. The values of the diffusion coefficient for seven proteins: aprotinin (6.5 kDa), α-lactalbumin (14.2 kDa), lysozyme (14.3 kDa), trypsin inhibitor (20.1 kDa), ovalbumin (44.2 kDa), bovine serum albumin (66.7 kDa), and phosphorylase b (97.2 kDa), were determined in the dilute region of 0-3 mg/ml. The results are compared with the Stokes-Einstein equation. The influence of the molecular structure and pH on the diffusion coefficient is discussed.