Amount Of Sodium Chloride Research Articles

The influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91

AbstractThe influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91 is studied in the laboratory. Samples were exposed under carefully controlled air and flow conditions; the relative humidity was 95%, the temperature was 22.0°C and the concentration of CO2 was < 1 ppm or 350 ppm. Different amounts of sodium chloride (0–70 μg/cm2) were added before exposure. The corrosion products were analyzed by gravimetry, ion chromatography, X‐ray diffraction and scanning electron microscopy. Mass gain and metal loss results are reported. The combination of high humidity and NaCl is very corrosive towards AZ91. However, the NaCl‐induced corrosion is inhibited by ambient concentrations of CO2. Exposure in the absence of CO2 gives rise to heavy pitting, with brucite, Mg(OH)2, being the dominant corrosion product. In the presence of CO2 a layer of hydrated magnesium hydroxy carbonate, Mg5(CO3)4(OH)2 · 5 H2O forms. A tentative corrosion mechanism is presented that explains the behavior in the two environments.

Combustion of TiO 2–Mg and TiO 2–Mg–C systems in the presence of NaCl to synthesize nanocrystalline Ti and TiC powders

The combustion process of TiO 2–Mg and TiO 2–Mg–C systems with sodium chloride as an inert diluent was investigated. The values of combustion parameters and temperature distribution on a high-temperature wave according to the amount of sodium chloride were obtained by the thermocoupling technique. The leading stages of combustion processes are found and the sizes of reactionary zones were estimated. It is shown that the introduction of NaCl in an initial mixture promotes the formation of a nanocrystalline structure of the final products. As a result, nanosized titanium, and titanium carbide powders have been successfully obtained.

Effect of Screening of Intermicellar Interactions on the Linear and Nonlinear Rheology of a Viscoelastic Gel

We report our studies of the linear and nonlinear rheology of aqueous solutions of the surfactant cetyl trimethylammonium tosylate (CTAT) with varying amounts of sodium chloride (NaCl). The CTAT concentration is fixed at 42mM and the salt concentration is varied between 0mM to 120mM. On increasing the salt (NaCl) concentration, we see three distinct regimes in the zero-shear viscosity and the high frequency plateau modulus data. In regime I, the zero-shear viscosity shows a weak increase with salt concentration due to enhanced micellar growth. The decrease in the zero-shear viscosities with salt concentration in regimes I I and III can be explained in terms of inter-micellar branching. The most intriguing feature of our data however, is the anomalous behavior of the high frequency plateau modulus in regime II (0.12 $\le \frac{[NaCl]}{[CTAT]} \le$ 1. 42). In this regime, the plateau modulus {\it increases} with an increase in NaCl concentration. This is highly counter-intuitive, since the correlation length of concentration fluctuations and hence the plateau modulus $G_{\circ}$ are not expected to change appreciably in the semi-dilute regime. We propose to explain the changes in regime II in terms of the unbinding of the organic counterions (tosylate) from the CTA$^{+}$ surfaces on the addition of NaCl. In the nonlinear flow curves of the samples with high salt content, significant deviations from the predictions of the Giesekus model for entangled micelles are observed.

New pyridinecarboxamides for rapid extraction of palladium from acidic chloride media

The extraction of palladium(II) from hydrochloric acid solutions of various concentrations in the presence of different amounts of sodium chloride with various defined alkylpyridinecarboxamides having one or two alkyl groups in the amide substituents at positions 2, 3 or 4 was studied. The hydrophobicity of the studied reagents was characterized by various parameters, including octanol/water distribution coefficient. It was found that the extraction of palladium(II) with monoalkylpyridinecarboxamides depends upon the number, length and position of the alkylamide group. Higher extractions are observed for the derivatives with the alkylamide group at position 3. The extraction of palladium(II) from aqueous 0.1 M HCl with N-dodecylpyridine-3-carboxamide (3-C 12) is rapid and the equilibrium is achieved in 30–60 s. The replacement of HCl with NaCl has only a minor effect on the extraction of palladium(II). During the extraction of palladium(II) from acidic solutions, HCl is also transferred to the organic phase. High transfer of HCl is observed for N-dodecylpyridine-3-carboxamide. A spontaneous transfer of palladium(II) to the organic phase is observed. The Vosburgh and Cooper method and the Job method were used to determine the composition of the complexes formed. Complexes with the molar ratio of palladium(II) to the extractant equal to 1:2 (PdCl 2L 2) and 1:1 (Pd 2Cl 4L 2) are extracted.

Design of Salbutamol EOP Tablets from Pharmacokinetics Parameters

Salbutamol elementary osmotic pump (EOP) tablets were developed, and fundamental variables affecting their release characteristics were evaluated. The effects of film thickness and compression force on drug release from the tablets containing fixed amount of sodium chloride used as osmogent were evaluated. The core tablets were directly compressed at four compression forces and coated with 3% wt/vol cellulose acetate in acetone to levels of 2%, 3%, and 4% wt/wt. Coated tablets were drilled with CO2 laser beam to form drug delivery orifice of ∼400 μm in diameter. The drug release was found to follow zero order fashion. The release rate decreased with the increased film thickness and was not affected by the compression force or porosity. The tablets coated to 3% and 4% levels exhibited the release rates within the range calculated from pharmacokinetic data. To illustrate the effect of osmogent content, the tablets were prepared at four osmogent levels and compressed at a constant compression force. The core tablets were coated to a level of 3% wt/wt. The release rate was initially increased with osmogent content and then decreased. At higher osmogent contents, the drug fraction in soluble component was decreased and resulted in the reduction of drug release. In conclusion, film thickness and osmogents played important roles in drug release from EOP tablets.

A Feasible SIMS Study for Characterizing Ferric Oxyhydroxides Formed on the Iron Surface Using Deuterium

Secondary ion mass spectrometry (SIMS) has been applied to hydrogen and deuterium analysis for ferric oxyhydroxides, which is formed by reaction of an iron substrate with water; either H2 Oo r D 2O containing a small amount of sodium chloride. Mass spectra of positive and negative ions obtained by SIMS showed that deuterium in ferric oxyhydroxides can be differentiated from hydrogen, although many species of secondary ion peaks are detected. Mass spectra from an iron sample, which firstly reacted with H2O, subsequently dried and finally reacted with D2O, indicated that D2O reaches a reaction front of the iron substrate through ferric oxyhydroxides formed by reaction with H2O. This implies that the ferric oxyhydroxides formed by reaction with H2O are, more or less, porous and thus water penetrates into ferric oxyhydroxides to the substrate. These results also suggest that SIMS analysis using isotopes enable us to characterize a formation process of ferric oxyhydroxides and permeability of foreign ions in the ferric oxyhydroxides.

Optimisation of Fenton’s reagent usage as a pre-treatment for fermentation brines

Pre-treatment of fermentation brines from green olives has been carried out by the Fe(II)/Fe(III)/H 2O 2 system. Reagent concentration exerted a positive influence on chemical oxygen demand (COD) removal. Hydrogen peroxide uptake showed values in the range 0.3–1.6 mol of COD eliminated per mol of H 2O 2 consumed depending on operating conditions. The optimum working pH was found to be in the interval 2.0–3.5. Reaction temperature increased the COD degradation rate, although similar COD conversion values were obtained after 5 h of treatment regardless of the value of this parameter. An analysis of the biodegradability of this type of effluent demonstrated the beneficial effect of the chemical pre-oxidation. According to the experimental results, it is suggested that there is an inhibitory effect of the wastewater due to its COD content and nature rather than attributable to the presence of high amounts of sodium chloride. Biodegradation efficiency increased as temperature was raised up to 30 °C. A further increase of this parameter up to 40 °C resulted in the death of the microorganisms.

Influence of excipients, drugs, and osmotic agent in the inner core on the time‐controlled disintegration of compression‐coated ethylcellulose tablets

The effect of excipient, drug, and osmotic agent loaded in the inner core tablet on the time‐controlled disintegration of compression‐coated tablet prepared by direct compression with micronized ethylcellulose was investigated. The excipients [spray‐dried lactose, hydroxypropyl methyl cellulose, sodium starch glycolate, microcrystalline cellulose, different drugs (sodium diclofenac: model drug, salbutamol sulfate, and theophylline anhydrate) and osmotic agent (sodium chloride)] were used to formulate the composition of the inner core tablet. The result indicates that drug release from all the compression‐coated tablets was characterized by a distinctive lag of time followed by a faster drug release, dependent on the types of excipient and drug, and osmotic agent used in the inner core tablet. Respectively, the lag of time was 8.5, 12.4, 14.6, or 15.8 h for spray‐dried lactose, hydroxypropyl methyl cellulose, sodium starch glycolate, or microcrystalline cellulose‐loaded inner core tablet, as compared with 16.4 h for an inner core made of sodium diclofenac alone. The direct‐compressible excipients such as spray‐dried lactose, sodium starch glycolate, and microcrystalline cellulose seemed not to illustrate a marked disintegration function to rapidly rapture the outer coating layer. The lag of time was only slightly shortened from 16.4 to 14.6 h, >24 to 17.8 h, or >24 to 21.3 h for sodium diclofenac, theophylline anhydrate, or salbutamol sulfate incorporated with sodium starch glycolate into the inner core tablet, respectively, suggesting that sodium starch glycolate did not perform its superdisintegration. Once an osmotic agent of sodium chloride was incorporated into the inner core tablet, the lag of time for the compression‐coated tablet was markedly shortened to <1 h, as compared with 16.4 h for drug alone. The more the amount of sodium chloride added, the less the time of lag obtained. Osmotic pressure did have a key role in controlling the drug dissolution. The present result implies that osmotic function is more suitable than superdisintegration function in designing a compression‐coated tablet with time‐controlled disintegration. © 2002 Wiley‐Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:2040–2046, 2002

Development of a stable solution of 5-aminolaevulinic acid for intracutaneous injection in photodynamic therapy.

Photodynamic therapy using 5-aminolaevulinic acid (ALA) as a photosensitiser is a new treatment modality for basal cell carcinomas. Until now ALA has been used topically as a cream. As this administration route leads sometimes to insufficient penetration in the skin, an intracutaneously injectable solution of ALA was developed. The influence of pH, concentration and temperature on the degradation of ALA in aqueous solution was investigated in order to optimise the formulation of the injection. In 0.1% ALA solutions with pH values between 4 and 8 a pH dependency of ALA degradation was shown, comprising fast decomposition at pH values higher than 7, whereas at a pH value of 6 or lower the solutions remained within the range of 90-110% of the initial concentration for at least 128 days. An increase of degradation rate with increasing concentrations became evident which is consistent with the supposed second-order degradation kinetics. After accelerated stability research at 63 degrees C and 85 degrees C a shelf life of 281 days for a 0.1% ALA solution pH 5 was calculated from an Arrhenius plot. A 2% ALA solution was proven to be isotonic. From our results a 0.1-2% ALA solution with pH 5 and an appropriate amount of sodium chloride to obtain isotonicity is recommended as an injectable solution.

Measurement of extravascular lung water in hemodialysis patients using blood ultrasound velocity and optical density dilution.

In hemodialysis patients, volume homeostasis is an important clinical problem. The aim is to have patients at an ideal "dry weight" postdialysis, but current methods for accurately measuring dry weight are disappointing. Krivitski et al. (ASAIO J 1998;44:M535-M540) have described a novel technique whereby extravascular lung water (EVLW) may be measured using blood ultrasound velocity and electrical impedance dilution. They have tested this method in animals and achieved agreement between obtained versus gravimetric measurements. Isotonic saline is used as a nondiffusible indicator and hypertonic (5%) saline is used as a diffusible indicator. By injecting these solutions and following their transits through the cardiopulmonary circulation, a theoretic basis for the calculation of EVLW may be derived from the cardiac output, the water transferred to blood, the amount of sodium chloride moved from blood to lung, and the increase in blood osmolality measured at the moment of osmotic equilibrium. We have used this new technique to measure EVLW for the first time in humans in 18 stable hemodialysis patients with no cardiac problems. Measurements were carried out twice in each patient, the first early in dialysis, the second toward the end of a dialysis session where fluid removal took place. The values for EVLW were 260+/-49 ml early in dialysis and 230+/-48 ml late in dialysis. This fall of 30+/-45 ml was statistically significant (p = 0.011). EVLW normalized to body weight was 3.29+/-1.0 ml/kg early and 3.02+/-1.04 ml/kg late in dialysis, a nonsignificant difference (p - 0.073). The normalized EVLW values are almost identical to those obtained in animals (3.1+/-1.4 ml/kg) by Krivitski et al. (see above). We conclude that this new technique can conveniently and noninvasively give an estimate of EVLW in hemodialysis patients. The clinical value of this measurement has now to be determined.

Synchronous multilayered adsorption of macrocations and macroanions on colloidal spheres. Influence of foreign salt and basicity or acidity of the macroions

The influence of foreign salt, the basicity or the acidity of macroions and the equivalency of the number of ionic groups of macrocations and macroanions upon alternate multiple adsorption on surfaces of colloidal silica (CS91, 110 nm in diameter) and polystyrene spheres (D1A19, 220 nm) have been studied by electrophoretic light scattering measurements. The macrocations used were poly(4-vinyl-N-n-butyl pyridinium bromide (C4PVP, strongly basic), poly(4-vinyl-N-ethyl pyridinium bromide (C2PVP, strongly basic) and poly(allylamine) (PAL, weakly basic). Sodium poly(styrene sulfonate) (NaPSS, strongly acidic) and sodium polyacrylate (NaPAA, weakly acidic) were used as macroanions. The alternate adsorption disappears even in the presence of a small amount of sodium chloride. The alternate multiple adsorption takes place on the addition of C4PVP first and NaPSS next, PAL first and NaPAA next, NaPAA first and C4PVP next, and NaPAA first and PAL next on the CS91 spheres. The influence of the equivalency of the number of ionic groups of C2PVP and NaPAA has been studied for the adsorption on the D1A19 spheres. The synchronous delicate balancing of the electrostatic interactions among the macrocations, the macroanions and the surfaces of the colloidal spheres is important for the alternate multiple adsorption.

Rheological properties of sodium montmorillonite in exhaustively deionized dispersions and in the presence of sodium chloride

The rheological properties of sodium montmorillonite particles were studied in exhaustively deionized aqueous dispersions and in the presence of a small amount of sodium chloride. The shear viscosities were several magnitudes higher than those expected from Einstein's coefficient and decreased sharply when the concentration of sodium chloride increased. The storage moduli of deionized dispersions were constant, irrespective of the angular frequency, whereas they decreased sharply when the salt concentration and the angular frequency increased. The phase of the deionized dispersion was "solid" and transformed into "liquid" on the addition of sodium chloride.

Potassium Citrate Prevents Increased Urine Calcium Excretion and Bone Resorption Induced by a High Sodium Chloride Diet

The amount of sodium chloride in the diet of industrialized nations far exceeds physiological requirements. The impact of abundant dietary salt on skeletal health has yet to be established, but is potentially detrimental through increased urinary calcium losses. We examined the effect of increased dietary sodium chloride on urine calcium excretion and bone turnover markers in postmenopausal women and, further, whether potassium citrate attenuates the effects of increased dietary salt. Postmenopausal women (n = 60) were adapted to a low-salt (87 mmol/d sodium) diet for 3 wk, then randomized to a high-salt (225 mmol/d sodium) diet plus potassium citrate (90 mmol/d) or a high-salt diet plus placebo for 4 wk. Urine calcium, urine N-telopeptide, urine cAMP, serum osteocalcin, and fasting serum PTH were measured at the end of the low- and high-salt diets. On the high salt plus placebo diet, urine calcium increased 42 ± 12 mg/d (mean ± sem), but decreased 8 ± 14 mg/d in the high salt plus potassium citrate group (P = 0.008, potassium citrate vs. placebo, unpaired t test). N-telopeptide increased 6.4 ± 1.4 nanomoles bone collagen equivalents per millimole creatinine in the high salt plus placebo group and 2.0 ± 1.7 nanomoles bone collagen equivalents per millimole creatinine in the high salt plus potassium citrate group (P < 0.05, potassium citrate vs. placebo, unpaired t test). Osteocalcin, PTH, and cAMP were not significantly altered. The addition of oral potassium citrate to a high-salt diet prevented the increased excretion of urine calcium and the bone resorption marker caused by a high salt intake. Increased intake of dietary sources of potassium alkaline salts, namely fruit and vegetables, may be beneficial for postmenopausal women at risk for osteoporosis, particularly those consuming a diet generous in sodium chloride.

Protein separation by high-performance membrane chromatography

High-performance membrane chromatography (HPMC) is a very effective Chromatographic method that combines the advantages of both membrane technology and column chromatography. In this work, proteins (myoglobin, conalbumin and soybean trypsin inhibitor) were separated by HPMC. The separation mechanism involved anionexchange, and the stationary phases were used anion CIM DEAE and QA disks (12x3 mm). Two types of mobile phase, buffer A (20 mM Tris-HCl, pH 7.4) and buffer B (buffer A+1 M NaCl) were used. As the amount of sodium chloride dissolved in buffer linearly increased, the retention time shortened and the resolution of the components was greatly improved. The optimum mobile phases and operating conditions were experimentally determined. From the experimental results, the proteins were separated within 2 min at a mobile phase flow rate of 4 ml/min.

Multiple Sources of Sodium Starch Glycolate, NF: Evaluation of Functional Equivalence and Development of Standard Performance Tests

Sodium starch glycolate is a commonly used super-disintegrant employed to promote rapid disintegration and dissolution of IR solid dosage forms. It is manufactured by chemical modification of starch, i.e., carboxymethylation to enhance hydrophilicity and cross-linking to reduce solubility. It has been reported in the literature that the source of starch, particle size, amount of sodium chloride (reaction by-product), viscosity, degree of substitution and cross-linking affect the functionality of sodium starch glycolate. Compendial assays provide an accurate representation of the chemical quality of an excipient, but they are not useful in describing the physical properties associated with the excipients. Physical characterization of sodium starch glycolate, NF revealed differences in particle size, surface area, porosity, surface morphology, and viscosity between two of the three sources examined. An automated liquid uptake test (in neutral and acidic medium) demonstrated similar initial rates of uptake, however, the extent of liquid uptake differed for the disintegrant powders examined. Settling volume was also observed to be different for the disintegrant from two sources. Lowering the pH of the medium reduced the rate and extent of liquid uptake and the settling volume in all instances. The extent of liquid uptake and settling volume was observed to be higher for the smaller sieve fractions in either medium. Although differences were also observed in the axial and radial disintegration force measurements of the pure disintegrant compacts, disintegration and dissolution of a model drug (hydrochlorothiazide) from either the soluble or insoluble core did not reveal any significant differences between the multiple sources.

Inclusion of Mother Liquor inside KCl Crystals in a Continuous MSMPR Crystallizer.

The crystal size distribution (CSD) and crystal purity of potassium chloride (KCl) have been measured in an MSMPR crystallizer by using two different impellers. A small amount of sodium chloride (NaCl) was added as an impurity tracer in order to measure the inclusion ratio of mother liquor inside KCl crystals. The effects of mixing, residence time, growth rate and crystal size of KCl on the inclusion of mother liquor were investigated. The crystal growth rate and nucleation rate were determined from the population density balance theory. The attrition of crystals changed round shape of the crystal and affected significantly the inclusion of mother liquor in the crystals. The roundness of KCl crystals was proposed as a new factor to take the attrition effects into consideration. An empirical relationship between the inclusion of mother liquor and the operating variables was obtained.

Micellar Solubilization of Oleic Acid and its Enrichment in Mixture with Stearic Acid

The optimum solubilization of oleic acid, an unsaturated fatty acid which is an important constituent in almost all fats, was determined using aqueous SDS micellar solution in presence of sodium chloride and n-butanol. Its solubilization in SDS micellar solution increases with an increase in concentration of SDS. Maximum solubilization of oleic acid was found to be at 11.0% SDS (w/w) and above it the solubilization decreases. Also solubilization of oleic acid in the above system was found to increase with addition of sodium chloride and n-butanol. At a concentration ratio 1:2 (w/w) of SDS and butanol, the solubilization of oleic acid was found to be the maximum. Oleic acid dissolved in SDS micellar solution can be extracted by adding excess amount of sodium chloride.

Growth of nonlinear optical γ-glycine crystals

Bulk crystals of γ-glycine have been grown at ambient temperature from aqueous solution in the presence of small amount of sodium chloride. The chemical composition of the grown crystal was determined by CHN analysis and infrared spectroscopy. The γ-phase was confirmed by powder XRD, single crystal XRD and differential scanning calorimetry. It was observed that γ-glycine generates second harmonic frequency of an Nd:YAG laser operating at 1064 nm. The second harmonic sconversion efficiency of γ-glycine is comparable with that of potassium dihydrogen phosphate.

A Comparison of Coulometric Titration and Potentiometric Determination of Chloride Concentration in Rumen Fluid

The concentration of chloride ions in rumen fluid is a useful measure of obstructive gastrointestinal disease in ruminants and camelids. However, rumen fluid is very different from other biological fluids in its bacterial populations, consistency, and concentrations of various anions. Two methods of determining the chloride concentration in biological fluids were compared using centrifuged and filtered rumen fluid containing different amounts of sodium chloride. Although coulometric titration and potentiometric electrode analysis yielded results that had a strong linear relationship, the results of potentiometry were consistently and significantly higher, by about 20 mEq/L. This difference was investigated further by analyzing a series of fluids containing different concentrations of sodium acetate. Acetate was detected as chloride (0.21 chloride molecules per acetate molecule) by potentiometry but not by coulometric titration. Therefore, the acetate concentration of rumen fluid was the most likely cause of the discrepancy between tests in the original trial. In conclusion, the coulometric procedure may be more accurate than the potentiometric procedure for measuring rumen chloride when the concentrations of possible confounding ions are unknown.

Size, Hydration, and Shape of SDS/Heptane Micelles Investigated by Time-Resolved Fluorescence Quenching and Electron Spin Resonance

Time-resolved fluorescence quenching (TRFQ) and electron spin resonance (ESR) are used to investigate sodium dodecyl sulfate/heptane micelles in water in the presence of varying amounts of sodium chloride (NaCl). Aggregation numbers are obtained from TRFQ and the micelle hydration from ESR. At any zero or any fixed sodium chloride concentration ≤375 mM, micelles grow with heptane while maintaining the volume fraction of water in the polar shell of the micelle, referred to as hydration index, constant. Core−shell model calculations, using simple geometry, show that some hydrocarbon density extends into the polar shell. The shell comprises about 15−17% of the core hydrocarbon in addition to the headgroups and hydration water. The rate of micelle growth with sodium chloride is smaller in the presence of heptane, and at higher salt concentrations (>375 mM), the micelles decrease in size with heptane. The rate of variation of hydration index with [NaCl] or aggregation number is indicative of micelle shape and shows that the sphere-to-rod transformation occurs at higher aggregation numbers and higher salt concentrations when heptane is present.