Magnesium Sulfate Heptahydrate Research Articles

Preparation and characterisation of magnesium sulphate heptahydrate from Kimberlite tailings

Weathered Kimberlite tailings of Panna Diamond Mines were characterised by DTA and XRD techniques. The XRD pattern shows the presence of serpentine, quartz, calcite, hematite, magnetite and anatase phases. DTA curve indicates first endothermic peak at 125‡C due to dehydration of the mineral and second endo peak at 670‡C due to dehydroxylation of serpentine closely followed by an exothermic peak at 810‡C associated with the formation of forsterite. XRD and DTA studies of sulphuric acid leach residue of the Kimberlite shows the disappearance of serpentine phase with the appearance of CaSO4·2H2O phase. The product MgSO4·7H2O obtained after purification and crystallisation. From the optical emission spectroscopic analysis, the product was found to contain Ca, Fe and SiO2 as trace impurities.

Solubility and density isotherms for magnesium sulfate heptahydrate-water-ethanol

Solubility data for use in the assessment of the drowning-out precipitation of magnesium sulfate heptahydrate in aqueous ethanol over the temperature range 15-35-degrees-C and the densities of the resulting saturated solutions are reported. In all cases, the presence of ethanol significantly reduces both the solubility and density of magnesium sulfate heptahydrate in aqueous solution. The solubility data may conveniently be expressed by a relationship of the form in W(eq) = A + Bx + Cx2 + Dx3 with an accuracy +/- 2% where W(eq) is the equilibrium saturation concentration of magnesium sulfate heptahydrate, expressed as kg of magnesium sulfate (hydrate)/100 kg of free water, and x is the concentration of ethanol expressed as kg ethanol/kg of free water.

Simple medium that preserves low concentrations of Escherichia coli for use in the water bacteriology proficiency test

A medium containing (per liter) 6.8 g of sodium acetate trihydrate, 3.4 g of potassium dihydrogen phosphate, and 0.1 g of magnesium sulfate heptahydrate (medium pH, 5.85 plus/minus 0.05) was developed for use in a water bacteriology proficiency test. The medium maintained 80 to 100 % viability of inoculated Escherichia coli at temperatures up to 31 degrees C for at least 12 days, while the concentrations of bacteria in the medium were as low as 20 bacteria per 100 ml. The medium remained stable after a year of storage. It has been used successfully to preserve bacteria in nine statewide bacteriology proficiency tests for potable and nonpotable water and has also been used in a nationwide pilot test. This report presents the results of these tests.

Permeability Testing in the Triaxial Cell

AbstractIt has been suggested that a triaxial shear test chamber can be used to measure the permeability of low permeability soils. To verify this, the influence of a number of test parameters on the measured coefficient of permeability was investigated. Results indicate such permeability tests should be performed on samples having a minimum diameter of 71.1 mm (2.8 in.) and a length to diameter ratio of 0.5 to 1.0. It was found that a permeant consisting of 1 g of magnesium sulfate heptahydrate (epsom salt) dissolved in 1 L of deaired, distilled water is adequate for general permeability testing. The triaxial, falling head permeability test should be conducted at a gradient that results in an applied effective stress at the outflow end of the sample less than the preconsolidation stress of the material. It was found that with very careful trimming, the influence of the smear zones created at the ends of the samples during the trimming process can be minimized.

Dehydration of magnesium sulphate heptahydrate investigated by quasi isothermal—quasi isobaric TG

With the help of the quasi isothermal-quasi isobaric technique, completed with DTA and thermomicroscopic examinations, several new observations have been made regarding the dehydration process of MgSO 4 · 7 H 2O. It was found that under given conditions the material, first at 50°C and then at 95°C, melts in an incongruous way. In the course of the latter transformation, a ternary system consisting of solid MgSO 4 · 3 H 2O, a solution phase saturated with respect to the trihydrate, and a water vapour phase, is formed. The saturated solution reaches its boiling point at 105°C. Without any temperature change, the system loses four moles of water and solid MgSO 4 · 3 H 2O remains. This decomposes at 115°C and a mixture consisting of MgSO 4 · H 2O and MgSO 4 · 2 H 2O forms, the proportion of which depends on the experimental conditions. At 150°C, the latter compound loses one mole of water. The MgSO 4 · H 2O maintains constant weight up to 310°C, above which temperature the remaining water of crystallization is removed.

Secondary nucleation and growth of magnesium sulphate heptahydrate in a fluidized bed

AbstractFrom both the theoretical and practical point of view, studies of secondary nucleation and crystal growth kinetics are of great importance, especially from point of view of varying hydrodynamic conditions. However, such a complex problem has not yet been solved. The present paper shows one of possible ways of approaching this problem using a fluidized bed crystallizer.

ESR studies of (Cu(H 2O) 6) 2+ in magnesium sulfate heptahydrate

ESR studies of (Cu(H 2O) 6) 2+ complex in magnesium sulfate heptahydrate are undertaken at 300, 150, and 77 K. The spin-Hamiltonian parameters at 150 K indicate a rhombic symmetry and are g x = 2.098 ± 0.002, g y = 2.089 ± 0.002, g z = 2.441 ± 0.002, ∥ A x ∥ = (22 ± 1) × 10 −4cm −1, ∥ A y ∥ = (18 ± 1) × 10 −4cm −1, and ∥ A z ∥ = (116 ± 1) × 10 −4cm −1. The ground-state wavefunction of the (Cu(H 2O) 6) 2+ complex at 150 K is calculated and the covalency and the admixture coefficient of ∥3 z 2 − r 2> into the ground state are estimated. The covalency reflected in the ground-state wavefunction is found to be in conformity with the optical absorption data. The temperature dependence of spin-Hamiltonian parameters is explained on the basis of dynamic Jahn-Teller effects.

Direct observation of secondary nuclei production

Production of secondary nuclei by low energy contacts between a crystal and a solid rod was investigated by direct microscopic observation. Crystal attrition occurred very easily and produced many secondary nuclei. Using both potash alum and magnesium sulphate heptahydrate growing in aqueous solution, large numbers of particles in the size range 1–10 μm were produced in both super- and undersaturated solutions. In addition larger pieces of crystalline material up to 50 μm in size were removed from the crystal under growing conditions. Many of the smaller particles grew very slowly in supersaturated solutions whereas the larger particles appeared to grow at rates characteristic of large crystals.

ChemInform Abstract: STUDY OF THE SALTHYDRATE, MAGNESIUM SULFATE HEPTAHYDRATE

Chemischer InformationsdienstVolume 7, Issue 8 Physical Inorganic Chemistry ChemInform Abstract: STUDY OF THE SALTHYDRATE, MAGNESIUM SULFATE HEPTAHYDRATE S. EL D. HAMAD, S. EL D. HAMADSearch for more papers by this author S. EL D. HAMAD, S. EL D. HAMADSearch for more papers by this author First published: February 24, 1976 https://doi.org/10.1002/chin.197608024Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue8February 24, 1976 RelatedInformation

Change in the crystal structure of zink(II) sulphate heptahydrate and magnesium(II) sulphate heptahydrate due to isodimorphous substitution by copper(II), iron(II), and cobalt(II) ions

AbstractThe physico‐chemical analytical data on the systems ZnSO4(MgSO4)–CuSO4(FeSO4, CoSO4 resp.)–H2O at 25.0°C have shown that due to isodimorphous substitution of Zn2+, Mg2+ resp., in the orthorhombic crystals of ZnSO4 · 7 H2O MgSO4 · 7 H2O, resp. for Cu2+, Fe2+ or Co2+ above a specific degree of ionic substitution, the orthorhombic crystals are converted into monoclinic mixed crystals. The crystal phases are characterized by X‐ray diffraction, microscopic and optical studies. The dominant effect of the admixed Cu2+, Fe2+, Co2+ ions is explained in terms of their electronic configurations, for which, owing to the operation of the Jahn‐Teller effect, a deformation of the regular octahedral arrangement of the water ligands about the metal ion is found to occur. The strongest deforming effect is that of Cu2+ ions followed by the Fe2+ ions, the weakest deforming effect being that of Co2+ ions.

Refinement of the crystal structure of magnesium sulphate heptahydrate (epsomite) by neutron diffraction

The crystal structure of orthorhombic MgSO4,7H2O has been refined anisotropically to a final R of 0·048 over 900 independent neutron reflexions from a synthetic crystal. For the positional parameters of the 14 crystallographically independent hydrogen atoms, estimated standard deviations are ca. 0·007 A, double those for the other atoms. All hydrogen atoms (mean O–H 0·964 A) are engaged in hydrogen bonds, ranging from 2·692(7) to 2·982(7)A. The W(7) water molecule, unique in that it is not co-ordinated to the magnesium, is engaged in relatively weak [(2·820(7) and 2·903(7)A] appreciably non-linear hydrogen bonds; it may be partially absent in water-deficient natural specimens. The assumption of coplanarity of water atoms and oxygen-acceptor atoms proves to be an unreliable guide to hydrogen positions.

Effect of Ni2+ on the EPR of Mn2+ Ions doped in single crystals of nickel salts

AbstractElectron paramagnetic resonance of Mn2+ has been studied in single crystals of magnesium sulfate heptahydrate (MgSO4 · 7 H2O) at 300°K. Mn2+ was found to substitute for Mg2+ and exhibit four inequivalent magnetic complexes corresponding to the tetramolecular unit cell of MgSO4 · 7 H2O. The results are compared with those for Mn2+ in isostructural NiSO4 · 7 H2O. The observed differences in the EPR of Mn2+ in crystals of the two salts are attributed to the magnetic interaction of Ni2+ and Mn2+.

Penicillium sclerotigenum: a new source of griseofulvin.

Penicillium sclerotigenum Yamamoto1 (CMI, 68,616) has been shown to produce griseofulvin. The fungus causes tuber rots of the Chinese yam, Dioscorea batatas. It was grown in Roux bottles in a medium containing 75 g ‘Dextrosol’, 2.9 g potassium nitrate, 5.0 g potassium dihydro-orthophosphate, 1.0 g magnesium sulphate heptahydrate, 1.0 g sodium chloride, 0.5 g ‘Difco’ yeast extract, and 1 ml. of minor element concentrate (containing 0.1 g ferrous sulphate heptahydrate, 0.015 g copper sulphate pentahydrate, 0.05 g zinc sulphate heptahydrate, 0.01 g manganese sulphate heptahydrate and 0.01 g. sodium molybdenate, in 100 ml.) made up to 1 l. with distilled water. The mycelium and broth were extracted with chloroform after 26 days growth.

THE HEAT CAPACITIES OF THE CRYSTALLINE AND VACUUM DEHYDRATED FORM OF MAGNESIUM SULPHATE MONOHYDRATE

Dehydration, under vacuum, of magnesium sulphate heptahydrate yields a product of monohydrate composition which does not give a diffraction pattern on X-ray examination and therefore has no evident crystalline structure. The heat capacity of this product has been determined over the temperature range from 90°K. to room temperature, and has been found to be substantially higher than that of the normal crystalline monohydrate. Consideration of these differences in heat capacity in conjunction with surface area data indicates that vacuum dehydration does not result in the formation of microcrystals the surfaces of which are available for gas adsorption. It is possible that aggregates of closely packed crystallites are formed in localized regions, these being interspersed with capillaries. Alternatively, it is possible that vacuum dehydration results in an intermediate state of ionic disorder.

THE LOW PRESSURE DEHYDRATION OF MAGNESIUM SULPHATE HEPTAHYDRATE AND COBALTOUS CHLORIDE HEXAHYDRATE

Rates of dehydration under vacuum, and at a series of controlled water vapor pressures, have been carried out for powdered samples of magnesium sulphate heptahydrate and of cobaltous chloride hexahydrate. It has been found for the magnesium salt that as the pressures are increased, the rate at first drops rapidly, this decrease being followed by a period of acceleration which is followed in turn by a decline. The curves are similar to those previously reported for copper sulphate pentahydrate, but the changes occur over a much wider range of water vapor pressures. In the dehydration of cobaltous chloride hexahydrate the initial drop in rate with increase in water vapor pressure is not observed. The results are interpreted in terms of the crystallization of intermediate products in the presence of adsorbed water.

A COMPARATIVE STUDY OF THE DEHYDRATION KINETICS OF SEVERAL HYDRATED SALTS

Rates of dehydration under full vacuum, and also as the pressure of water vapor due to the dehydration process was allowed to increase, have been determined for a number of hydrated salts. The dehydration of manganous sulphate tetrahydrate, zinc sulphate heptahydrate, nickel sulphate hexahydrate, and magnesium sulphate heptahydrate has been found to proceed through the formation of amorphous intermediates, the last two of these being very stable. The dehydration of nickel nitrate hexahydrate, magnesium nitrate hexahydrate, and probably of ferrous sulphate heptahydrate and cobalt chloride hexahydrate at very low pressures takes place with the formation of crystalline intermediates. The results obtained are discussed in relation to the dependence of rate of dehydration on water vapor pressure previously reported for copper sulphate pentahydrate and for manganous oxalate dihydrate.

Confirmation of the Space-Group of Epsomite

ALTHOUGH orthorhombic magnesium sulphate heptahydrate (epsomite) has been the subject of two previous investigations,1,2 in neither case was a complete structure proposed. We commenced work on this substance in the hope of carrying the knowledge of its structure to a more complete stage. Due to unforeseen circumstances, however, the investigation has been interrupted, and it is uncertain when the study can be resumed. We have considered it of interest to report some of our results, since they agree with those already in the literature, and thus serve as a third check on the dimensions of the unit cell and on the space-group.