Sodium Thiosulfate Pentahydrate Research Articles

Solvent extraction of acenaphthene from dodecane into aqueous β-cyclodextrin medium and application to synchronous spectrofluorimetric determination in kerosene

Acenaphthene can be selectively extracted from a dodecane phase into a water–dimethyl sulfoxide (20% v/v) medium containing β-cyclodextrin (10 mg cm–3), potassium iodide (300 mg cm–3) and sodium thiosulfate pentahydrate (15 mg cm–3) with a shaking time of 3 min. The distribution ratio for the solvent extraction was 0.292 with a relative standard deviation of 8.3% at 20 ± 1 °C. The amount of acenaphthene extracted from 1 cm3 of dodecane by three 8 cm3 successive batch extractions was 97.3% in calculations and 95.1% in practice. The extraction behaviours of several typical two- and three-ring aromatic compounds were investigated under the same conditions. Selective extraction based on complexation with β-cyclodextrin was applied to the synchronous spectrofluorimetric determination of acenaphthene in commercially available kerosene.

Performance of direct contact latent heat storage units with two hydrated salts

The performance of a direct contact latent heat storage unit, that consists of two columns with differnet hydrated salts, has been investigated. Na 2CO 3·10H 2O (sodium carbonate decahydrate) and Na 2S 2O 3·5H 2O (sodium thiosulphate pentahydrate) were contained in separate columns both having an inside diameter and total length of 0.184 m and 1.0 m, respectively. During heat charge, the hot kerosene as a heat transfer fluid was bubbled through the sodium thiosulfate solution first. The partially cooled kerosene was then pumped to the second column containing the sodium carbonate solution, discharging most of its heat content. Flow direction was reversed during heat discharge. The continuous phase temperature in the two columns, as well as kerosene inlet and outlet temperatures, were measured continuously. Results showed significant improvement in heat transfer rates by using two separate columns containing similar or different salts. The use of a combination of two different salts, having different crystallization temperatures, and contained in different columns connected in series, may provide better means of heat storage by allowing the system to operate as a phase change storage for longer periods of operation. This is particularly suitable for solar energy applications in which the collector temperature may vary significantly during the day.

Kinetics of dehydration of sodium salt hydrates

The kinetics of dehydration of sodium salt hydrates, namely sodium acetate trihydrate, sodium thiosulphate pentahydrate and disodium hydrogen phosphate dodecahydrate are reported. These salt hydrates have been recommended for thermal energy storage applica- tions. The kinetic analysis was carried out on a simultaneous DTA/TG apparatus. Kinetic parameters were evaluated from TG data. Ten models of possible controlling mechanisms have been considered for the determination of kinetic parameters. Results show that in these cases it is difficult to select a suitable mechanism for the determination of kinetic parameters using the best fit straight line method suggested by Coats and Redfern and the minimum standard deviation method suggested by Zsako. A new criterion is proposed in this work for the selection of a suitable mechanism.

Thermal stability of sodium salt hydrates for solar energy storage applications

Thermal stability of salt hydrates of sodium cation namely sodium hydroxide monohydrate, sodium acetate trihydrate, sodium thiosulphate pentahydrate, sodium carbonate decahydrate, sodium sulphate decahydrate and di-sodium hydrogen phosphate dodecahydrate has been evaluated at elevated temperatures using thermogravimetric technique. The energy of activation of dehydration of these salt hydrates have been reported. A new criterion based upon the ratio of percent water loss and energy of activation has been reported to determine the relative thermal stability of sodium salt hydrates.

Viscosity of a mixture of sodium isothiocyanate and potassium isothiocyanate in molten sodium thiosulfate pentahydrate: a case of positive deviation from additivity

Viscosity of a mixture of sodium isothiocyanate and potassium isothiocyanate in molten sodium thiosulfate pentahydrate: a case of positive deviation from additivity

The dehydration of Na2S2O3· 5H2O single crystals as studied by thermal analysis and optical microscopy

The dehydration of cleaved single crystal of sodium thiosulphate pentahydrate in vacuum or in flowing dry N2 has been studied employing optical microscopy and thermal methods. Evidence of the formation of a dihydrate as intermediate has been obtained in both dehydration and rehydration experiments. Comparative studies were made of reactions on single crystals cleaved parallel to three different crystallographic planes, but the dependence of the dehydration on face was ascertained only for the initial portions of vacuum or high-N2 flow experiments. Microscopic evidence and the initial splitting of the constant-temperature dehydration thermal curves indicated that, at the onset of dehydration, the formation of a fully dehydrated layer on the crystal surface takes place. The subsequent evolution of the transformation is determined by the properties of this layer. These in turn appear to depend on the perfection of the cleaved surface as well as on the efficiency of the dehydrating agents. Dehydration mechanisms for strong and mild dehydrating conditions are suggested, based on the presence of the dehydrated surface layer and on the formation of the intermediate dihydrate. Kinetic analysis of the constant-temperature thermal dehydration responses gave a good fit to the data of the pentahydrate-to-dihydrate transformation by a contracting circle equation, while for the dihydrate-to-anhydrous reaction an n= 2 Avrami–Erofeev law was obeyed. The sensitivity of the transformation to the defect content of the crystals and to the changes in N2 flow and temperature prevented the evaluation of reliable Arrhenius parameters, particularly for the first dehydration stage. However, this provides further support for the surface-layer mechanism proposed here, which is reputed to apply more generally to other dehydration reactions in place of the preceding nucleation-and-growth model.

ChemInform Abstract: Conductivity and Dielectric Relaxation in Calcium Nitrate Tetrahydrate and Sodium Thiosulfate Pentahydrate near Tg.

AbstractAdmittance data for Ca(NO3)2 ‐ 4 H2O (1) and Na2S2O3 ‐ 5 H2O (I) at temp. in the vicinity of the glass transition temp. (T3) are reported.

Conductivity and dielectric relaxation in calcium nitrate tetrahydrate and sodium thiosulfate pentahydrate near Tg

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConductivity and dielectric relaxation in calcium nitrate tetrahydrate and sodium thiosulfate pentahydrate near TgD. R. MacFarlane and D. K. Y. WongCite this: J. Phys. Chem. 1985, 89, 26, 5849–5855Publication Date (Print):December 1, 1985Publication History Published online1 May 2002Published inissue 1 December 1985https://doi.org/10.1021/j100272a055RIGHTS & PERMISSIONSArticle Views88Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (855 KB) Get e-Alerts

Dehydration kinetics of sodium thiosulphate pentahydrate in thermal energy storage

The kinetics of dehydration of sodium thiosulphate pentahydrate have been determined by the thermogravimetric technique. The data have been analysed using Freeman and Carroll's [5] graphical technique and Zsako's [6] standard deviation calculation method. The energy of activation and order of the reaction for different transitions have been determined. The enthalpies of various transitions have been calculated from weight-loss data. The results show that the energy of activation is proportional to the enthalpy of transition in this system.

Hydrates of sodium thiosulphate

Dehydration of sodium thiosulphate pentahydrate with organic solvents produces mixtures of the anhydrous salt and dihydrate for compositions up to 2H 2O and of di- and pentahydrates above this composition, with occasional traces of monohydrate present. This confirms the stable compounds in the Na 2S 2 O-H 2O system. The constituents in mixtures were identified qualitatively and semi-quantitatively by Raman spectroscopy. X-ray powder diffractometry is much inferior for identification purposes. Correlations between vibrational frequencies and structure are suggested.

Crystal growth velocity of sodium salt hydrates

Four sodium salt hydrates (sodium sulfate decahydrate, disodium phosphate dodecahydrate, sodium thiosulfate pentahydrate, and sodium carbonate decahydrate) have a relatively high heat of fusion and have been suggested by Telkes ( 7 ) as likely candidates for the storage of energy. The thermophysical properties, costs, means of preparation, and nontoxic nature of these materlals are all favorable. Trays of these salt hydrates in direct contact with air have been proposed for the storage of energy from solar energy collectors. Direct-contact, immiscible-fluid, batch crystallizers also have been proposed (2) as effective heat of fuslon energy storage devices. In order to design these energy storage systems, one needs data on the crystal growth rates of these sodium salt hydrates. Mechanlems of Crystal Growth. The formation of the solid phase from a solution occurs by two mechanisms: nucleation and growth. In the first mechanlsm crystal embryos lose or add molecules until a specific critical size is reached. Further increase In the slze of the crystal begins the second mechanism of crystal growth. The growth of each crystal face proceeds either in a neat uniform layer-upon-layer fashion or by the haphazard propogation of dislocations, dendrites, and eventually occlusions. As early as 1905 it was proposed that the diffusion of solute molecules through a thin laminar film of liquid adjacent to the growing crystal face is the rate-controlling step for crystal growth (3). A few years later it was suggested that the mass deposition rate is controlled by two steps, a diffusion step followed by a surface reaction of order LY

Thermodynamic properties and phase transitions of salt hydrates between 270 and 400 K I. NH 4Al(SO 4) 2 · 12H 2O, KAl(SO 4) 2 · 12H 2O, Al 2(SO 4) 3 · 17H 2O, ZnSO 4 · 7H 2O, Na 2SO 4 · 10H 2O, and Na 2S 2O 3 · 5H 2O

Heat capacities and phase-transition enthalpies have been measured for five sulphate hydrates and sodium thiosulphate pentahydrate by adiabatic-shield calorimetry between 270 and 400 K. Enthalpies and entropies have been derived for the exact stoichiometries and tabulated for selected temperatures. The enthalpy of fusion of NH 4Al(SO 4) 2 · 12H 2O at 367.13 K is (122.0 ± 0.9) kJ · mol −1. The enthalpy of transition of KAl(SO 4) 2 · 12H 2O to KAl(SO 4) 2 · 3H 2O plus aqueous solution at 358.99 K is (95.2 ± 1.2) kJ · mol −1. Including the enthalpy of dissolution of 3-hydrate, the total enthalpy of transition of KAl(SO 4) 2 · 12H 2O to an aqueous solution in the range 358.99 to 386 K is (112.7 ± 1.5) kJ · mol −1. Al 2(SO 4) 3 · 17H 2O melted in the range 350 to 381 K with enthalpy of fusion (120.5 ± 1.0) kJ · mol −1. The gradual onset of the phase transition is probably due to release of zeolitically bound water. The enthalpy of transition of ZnSO 4 · 7H 2O to ZnSO 4 · 6H 2O plus aqueous solution at 311.3 K is (16.5 ± 0.5) kJ · mol −1. The temperature of the peritectic transition of Na 2SO 4 · 10H 2O to Na 2SO 4 plus aqueous solution is (305.533 ± 0.002) K, and the phase-transition enthalpy (78.04 ± 0.3) kJ · mol −1. The enthalpy of transition of Na 2S 2O 3 · 5H 2O to Na 2S 2O 3 · 2H 2O plus aqueous solution at 321.31 K is (48.8 ± 0.6) kJ · mol −1. Including the enthalpy of dissolution of 2-hydrate, the total transition enthalpy of Na 2S 2O 3 · 5H 2O to an aqueous solution in the range 321 to 335 K is (51.8 ± 0.4) kJ · mol −1. Sulphate and thiosulphate hydrates may be of interest as energy-storage materials because of their high enthalpies of fusion, if supercooling and segregation of unwanted solid phases can be prevented.

Study of multicycle melting and freezing of sodium thiosulphate pentahydrate

AbstractThe behaviour of sodium thiosulphate pentahydrate in the course of repeated use as a heat‐storing medium can be predicted, cycle by cycle, on the basis of a generalised phase‐transition equation adapted for incongruently melting material. An indice is derived for this purpose and named ‘coefficient of true phase‐transition reversibility’. Its predictive value is shown for three additional incongruently melting materials well known as heat‐storing media: CaCl2.6H2O, Na2SO4.10H2O and the mixture Na2SO4.10H2O + 2/3NH4Cl + 2/3NaCJ.

Studies on low-temperature salt-hydrate for thermal storage applications

A novel thermal-energy storage concept involving the use of salt-hydrates such as sodium thiosulphate pentahydrate, Na 2S 2O 3·5H 2O is under investigation. With fusion temperatures of many salts lying between 0 and 100°C, such substances may be considered as likely materials to be used in conjunction with solar energy flat-plate collector systems for domestic use. Phase change storage or latent heat storage is concluded to be a promising technique for storing solar energy. The solid-liquid transformation of salt-hydrates is actually a dehydration or hydration of salt, although this process resembles melting or freezing thermodynamically. Three types of behaviour can be identified: congruent, incrongruent, and semicongruent melting. None of the congruent melting salt-hydrates have been judged for use in thermal storage because of cost and safety considerations.

Sodium thiosulfate pentahydrate: a redetermination by neutron diffraction

Sodium thiosulfate pentahydrate: a redetermination by neutron diffraction

Solar energy conversion through phase transformations

Sodium thiosulphate pentahydrate and sodium sulphate decahydrate show appreciable potential differences and currents when the solid phase is in contact with its molten phase. the studies offer a new method for converting solar energy into electrical power.

Observations on brilliant green agar with H2S indicator.

Several formulations of brilliant green agar with an added H2S indicator were evaluated. Results were optimum with variations of a basic formula consisting of 40 g of tryptic soy agar (Difco), 8 g of lactose, 8 g of sucrose, 80 mg of phenol red, 1 g of sulfanilamide, 1.5 g of ferric ammonium citrate, 5 g of sodium thiosulfate pentahydrate, and 7 mg of brilliant green dye per liter. Brilliant green dye was added after sterilization of the other components This formulation supported good growth of all of 39 strains of Salmonella tested. Normal biochemical types formed pink colonies with black centers, and an H2S-negative S. choleraesuis formed pink colonies without black centers. Of other bacteria tested, only Enterobacter, Klebsiella, and a few Citrobacter strains showed significant growth in 24 h. When lactose was omitted from the formulation, a lactose-fermenting strain formed pink colonies with black centers, and differentiation of Salmonella from the Enterobacter-Klebsiella groups was equally good. Addition of xylose (4.0 g) and L-lysine hydrochloride (5.4 g) to the above formulation improved differentiation between Salmonella and the few Citrobacter strains that grew and produced more intense blackening in Salmonella colonies. Addition of an H2S indicator to brilliant green agar formulations aided in identification of Salmonella colonies, especially in mixtures with other bacteria. These media were judged to give better differentiation of salmonellae from other bacteria than Hektoen agar with added novobiocin (10 mg/liter).

Thermal energy storage for solar heating and off-peak air conditioning

Latent heat thermal energy storage materials suitable for solar heating and off-peak air conditioning were investigated and evaluated in terms of criteria developed to judge their usefulness. The often recommended sodium sulfate decahydrate and its mixtures were shown to have undesirable melting properties, causing a reduction in storage capacity upon repeated cycling. Materials more suitable at present are paraffin waxes for solar heating and paraffin waxes and tetrahydrofuran hydrate for off-peak air conditioning. Sensible heat storage has the economic advantage of not requiring heat transfer surfaces between storage and collection and between storage and delivery. Latent heat storage provides operational advantages of smaller temperature swings and lower, more efficient solar collector temperature, smaller size and lower weight per unit of storage capacity. The optimization of the thermal energy storage subsystem is dependent on the collection and delivery characteristics of the system. Parametric designs for two latent heat materials (sodium thiosulfate pentahydrate and a paraffin wax) and for a sensible heat material (a 1:1 mixture of water and ethylene glycol) were compared as to cost, performance, and space requirements. The conditions of equal cost for latent heat and sensible heat storage systems were determined as functions of latent heat capacity, thermal conductivity, and the temperature swing allowed in the sensible heat storage tank. The comparative designs include the cost of the heat exchanger required for latent heat storage and the operating penalty due to storage temperature swings inherent in sensible heat storage.

Neutron diffraction study of sodium thiosulphate pentahydrate, Na2S2O3.5H2O

A single-crystal neutron-diffraction investigation of sodium thiosulphate pentahydrate, Na2S203.5H20, has been made with three sets of zonal data. The structure was refined by least-squares techniques, with individual temperature factors, to an R value of 8.2%. The geometry of the $203 group and sodium-oxygen framework agree with those of X-ray studies. The positional parameters of some of the atoms differ from those p3stulated from the X-ray and nuclear magnetic resonance studies. The O-H and H-H bond distances and the H-O-H valence angle of all the five water molecules were found to be normal. The hydrogen-bond scheme falls into four classes: two strong water-thiosulphate oxygen, two weak water-thiosulphate oxygen, two water-water, and three water-sulphur hydrogen bonds. From the geometry of its surroundings one of the hydrogen atoms H(9) may be regarded as not participating in hydrogen bonding.

The Temperature Dependence of Transport Properties of Ionic Liquids. The Conductance and Viscosity of Calcium Nitrate Tetrahydrate and Sodium Thiosulfate Pentahydrate

The Temperature Dependence of Transport Properties of Ionic Liquids. The Conductance and Viscosity of Calcium Nitrate Tetrahydrate and Sodium Thiosulfate Pentahydrate