The reaction of sodium arsenite with sodium chlorite

Existing procedures for the standardisation of sodium chlorite solutions are critically examined and a suitable method detailed. The reaction between sodium chlorite and sodium arsenite solutions is discussed; reaction is quantitative in the presence of sodium bicarbonate and osmic acid as catalyst.     

Effect of sodium salicylate, sodium oxalate, and sodium chloride on the micellization and adsorption of sodium deoxycholate in aqueous solutions

The salicylate ion increases the rate of bile flow (choleretic effect) and bile salts are known to affect the colonic absorption of oxalate. Owing to this physiological relevance of salicylate and oxalate ions, critical micelle concentration (cmc) values of sodium deoxycholate (NaDC) were determined in aqueous sodium oxalate, sodium salicylate, and sodium chloride solutions by using surface tension, fluorescence, and EMF methods. The results indicate, besides a counterion effect, the influence of coanions on the cmc. In the range from 25 to 40 °C, cmc increases almost linearly with temperature. In the temperature range from 30 to 40 °C, the counterion binding constant β of NaDC micelles has the same value (0.17±0.01) in the presence of sodium chloride and sodium salicylate. On the other hand, in sodium oxalate solution β=0.05±0.02 when oxalate concentration is less than or equal to c* and β=0.48±0.04 above c*, where c*≈0.038 mol kg(-1). EMF measurements also supported this type of counterion binding to NaDC micelles in sodium oxalate solutions. In sodium oxalate solution, at c* a change in the shape of deoxycholate micelles is expected to take place. Salicylate, oxalate, and chloride coanions have a similar effect on the adsorption of NaDC. This study reveals that the choleretic effect of salicylate is not due to the influence of salicylate ions on the micellization of NaDC.     

硝普钠分光光度法测定头孢噻肟钠

建立了测定头孢噻肟钠的新方法,碱性溶液中硝普钠与头孢噻肟钠生成了化学计量比为2∶1的产物,其最大吸收波长λmax=525 nm,表观摩尔吸光系数3.9×103L.mol-1.cm-1。头孢噻肟钠在0.91~200μg/mL浓度范围内与吸光度呈现良好线性关系,线性回归方程A=0.010+0.00816ρ(μg/mL),线性相关系数r=0.9994,检出限(3σ/k)为0.62μg/mL。方法可用于药物样品和血清中头孢噻肟钠含量的测定。     

XPS characterization of sodium percarbonate granulated with sodium silicate

Granular sodium percarbonate has been characterized by X-ray powder diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The O1s binding energy for the solvating hydrogen peroxide molecules is 535.8 eV. Sodium percarbonate is stabilized by sodium silicate and polyphosphate.     

Preparation of sodium borosilicates using sodium silicate and boric acid

The gelling behaviour of an aqueous sodium silicate solution with boric acid was investigated for different initial compositions and solid sodium borosilicate samples were obtained by drying the gels at 100°C, 225°C and 450°C. The chemical composition, dissolution, pH, loose-packed bulk density, B.E.T. surface area, moisture, size distribution and XRD/IR patterns of the sodium borosilicate particles were determined. The minimum gelling times were observed at pH values between 9–10 and although no gels were obtained using HCl at pH = 11, the silicate solution was gelled with boric acid suggesting borate ions promote the formation of siloxane network and behave as a crosslinking agent.     

Aggregation of sodium dodecyl sulfate in aqueous sodium chloride solutions

Summary Aqueous solutions of sodium dodecyl sulfate with added sodium chloride (0–0.3 mol kg^–1) were studied at 298.2 K in order to calculate the molar standard free energy of micelle formationG _m . The following properties were measured: (i) aggregation number by membrane osmometry, (ii) counter-ion binding and sodium ion activities by electromotive force, (iii) critical micelle concentration by electromotive force and fluorescence spectrophotometry. The results indicate thatG _m . is independent of the NaCl concentration.     

Determination of sodium ion diffusion coefficients in sodium vanadium phosphate

Carbon-coated Na₃V₂(PO₄)₃ (NVP) was prepared by a standard sol–gel procedure. The apparent diffusion coefficients of sodium ions in the rhombohedral NVP have been determined by different techniques such as galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV). It was found that the apparent diffusion coefficients range from 6?×?10^?13 cm² s^?1 to 2?×?10^?15 cm² s^-1. These sodium ion apparent diffusion coefficients follow a similar trend as observed for lithium ions in the closely related monoclinic modification of Li₃V₂(PO₄)₃, demonstrating a minimum at the potential where the ion extraction/insertion occurs.     

Disposable sodium electrodes

In this paper we describe a disposable sodium sensor in double matrix membrane technology. This sensor is prepared from filter paper with an evaporated silver conducting line on one side. For insulation the sensor is laminated with a pre-perforated heat-sealing film. A defined volume of an ion-sensitive polymer matrix membrane cocktail is filled into one hole. So an ion-sensitive coated film sensor in double matrix membrane technology is produced. The double matrix membrane is formed by the polymer matrix membrane and by the additional filter paper matrix. The response behaviour of the sodium electrode is comparable with conventional macro ion-selective electrodes. By this technology a mass production of low cost sensors is possible.     

Glycine sodium nitrate

The glycine mol­ecule in the title compound, Na(NO₃)·C₂H₅NO₂, exists in the zwitterionic form. The Na atom exhibits eightfold coordination and the polyhedron may be visualized as a distorted hexagonal bipyramid. The glycine mol­ecules are linked through head-to-tail hydrogen bonds and are found `sandwiched' between the Na(NO₃) layers.     

Thermal behaviour of diclofenac, diclofenac sodium and sodium bicarbonate compositions

This work aims to investigate the thermal behaviour of diclofenac, diclofenac sodium, and NaHCO₃ both as single components and binary mixtures. In particular, the melting point and latent heat of fusion binary diagrams of the diclofenac sodium/diclofenac mixtures at different mole fraction compositions were investigated in order to gain information about the thermal behaviour of their solid mixtures. A good agreement between liquidus curves, calculated by the Schroeder-Van Laar equation from fusion enthalpies and temperatures, and the experimental results was found. For all binary compositions, an endothermic effect at 153°C, probably due to the eutectic fusion, is present.     

Metal-insulator transitions in microclusters? Mixed sodium/sodium chloride aggregates

Photoionization measurements on cluster beams obtained by coexpanding sodium and sodium chloride vapors allow inferences regarding the thermodynamic stability of a number of mixed metal/salt aggregates. We discuss the possibility of observing composition dependent metal/insulator transitions among clusters with a fixed number of monomer units.     

Efflorescence relative humidity of mixed sodium chloride and sodium sulfate particles

We study the efflorescence relative humidity (ERH) of particles composed of sodium chloride and sodium sulfate. Both experimental and theoretical investigations are conducted to explore the effects of particle size and mixing ratios between two inorganic materials on ERH. A previously developed theoretical model (Gao et al. J. Phys. Chem. A 2006, 110, 7602; ref 1) is applied as the framework to build a formulation assuming that one salt nucleates much faster than the other, and the critical nuclei formation of the former controls the rate of efflorescence. The predicted ERHs agree favorably with the experimental data, except for particles containing Na2SO4 in a mole fraction of around 0.25. At this composition, our model underestimates the ERH, indicating certain factors involved in the efflorescent processes that are overlooked in our formulation. Relative to particles larger than 40 nm, the Kelvin effect more significantly affects particles smaller than this size.     

二氧化碳和水气氛对高钠煤转化过程中钠迁移的影响

对新疆的两种高钠煤（伊犁煤YL、呼图壁煤HTB）进行了N₂、CO₂和H₂O气氛和不同温度下钠迁移的研究。采用逐级萃取和湿法消解法确定了原煤、半焦中钠的赋存形态,定量研究了两种煤中钠的挥发及迁移规律。结果表明,YL煤的形态钠中水溶钠占80.08%,HTB煤的形态钠中不溶钠占61.54%。不同气氛下,升高温度都可促进两种煤中钠的挥发,半焦中水溶钠比例减小,醋酸铵可溶钠比例会出现先增加后减少现象,盐酸可溶钠比例呈增加趋势。对于YL煤,CO₂气氛可抑制钠的挥发,H₂O蒸气可促进钠的挥发;900℃时,YL煤CO₂气氛下钠挥发仅为N₂气氛下的50.25%,而H₂O气氛钠挥发为N₂气氛下的111.45%。对于HTB煤,CO₂气氛也可抑制钠的挥发,900℃时CO₂气氛下钠挥发为N₂气氛的80.91%;HTB煤在H₂O蒸气下,800℃之前钠挥发高于N₂,当900℃时,钠挥发略低于N₂气氛。YL煤形态钠中以水溶钠为主,其挥发的同时会向盐酸可溶钠及不溶钠转变。而HTB煤形态钠中以不溶钠为主,其次是水溶钠,CO₂和H₂O气氛能促进不溶钠向其他可溶态钠转变。     

Mass-spectrometric examination of vaporization of sodium nitrite and sodium and potassium nitrates

Vaporization of sodium nitrite and sodium and potassium nitrates was examined by high-temperature mass spectrometry. The inverse temperature dependences of the vapor pressure logarithm for these compounds were presented. Enthalpies of vaporization and standard enthalpies of formation of gaseous NaNO₂, NaNO₃, and KNO₃ were determined.     

Micellisation behaviour of mixtures of sodium dodecylsulphate and sodium lauroylsarcosinate in water

The critical micelle concentrations of binary mixtures of sodium dodecylsulphate (SDS) and sodium lauroylsarcosinate (SLAS) have been determined in water by conductivity measurements at different mole fractions for each of the components. The critical micelle concentrations were slightly lower than that predicted from ideal mixing theory indicating positive synergistic interactions in mixed micelle formation. The results of the mixed systems were analysed using the Regular Solution Theory and the approach based on the Gibbs–Duhem equation which allowed for the determination of the composition of the mixed micelle, the activity coefficients and the pair-wise molecular interaction parameter β. The β values were all negative at all mole fractions investigated, showing a slight deviation from ideality, with an average value of –0.27. The excess free energy of the mixed systems was also calculated and the values were all negative for the mixed systems studied, an indication that the mixed micelles are thermodynamically stable relative to the individual component. This thermodynamic parameter also exhibits symmetrical behaviour with respect to micellar composition suggestive of a regular solution behaviour of the mixed surfactant system.