Osmotic Pressure Of Solution Research Articles

Dewatering of Dead Sea Brine by Osmosis

AbstractThe first stage in the production of potash from the Dead Sea involves removal of water from Dead Sea Brine by solar evaporation. The pond function can be supplemented by osmosis, utilizing as a dewatering agent End Brine, a high osmotic pressure solution, available in large quantities as a waste stream from the solar evaporation process. For this osmosis service, asymmetric membranes, i.e. those possessing a dense skin surmounting a porous substructure, were examined. These were tubular membranes 16 mm in diameter. The membranes were of cellulose acetate, fabricated by the Loeb‐Sourirajan technique. The principle objective was to obtain a water permeation flux (permeation rate per unit area) sufficiently high for economic operation. Parameters examined included (1) casting solution composition; (2) temperature to which the membrane was heated in the casting process; (3) circulating brine flow characteristics; (4) effect of using diluted End Brine; (5) influence of reinforcing sleeve; (6) total membrane thickness. Of these parameters the last was found to be most important. At 70 microns, the minimum practical thickness, the flux was still too low. The experimental results were supported by a transport analysis of osmotic flow through an asymmetric membrane. This analysis indicated that any asymmetric membrane of the same thickness, regardless of its chemical composition would also have such low flux because flux is limited by the necessary back diffusion rate of dissolved salt in the porous substructure and by the high salt concentrations within it.

Osmotic pressure of polystyrene in toluene solutions, measured over wide ranges of concentration and degree of polymerization of the polymer

The osmotic pressure in solutions of polystyrene in toluene is measured as a function of concentration and degree of plymerization of the polymer. The volume fraction of the polymer in the solution studied ranges up to 0.15, and the degree of polymerization of the practically monodisperse polymers ranges from 40 to 6000. The experimental data are discussed in terms of the parameter q, defined as the ratio between the number of nearest neighbours of a polymer molecule, and the number of nearest neighbours of a solvent molecule. All estimated values of q are smaller than 0.25 r, where r is the degree of polymerization of the polymers. This result is taken as experimental evidence that in solutions of polystyrene in toluene less than one fourth of the surface area of a polymer segment is exposed to the solvent. The maximal value of q/r is observed for the most concentrated solutions studied, and for dilute solutions of polystyrene with a degree of polymerization below 100.

The diversity of moulds in the candied salak (Salacca edulis Reinw.)

The aims of this research were to identify moulds in candied fruit within three varieties of salak (i.e. sleman, gading and pondoh), and to know the effect of sugar concentration added, the time of storage, and additional of preservative chemical substance (benzoic acid) for the diversity of moulds in candied salak. The isolation method of moulds was used direct plating. In order to determine the kind of moulds, which tolerance in sugar solution (osmotic pressure), the samples were put on the surface of glucose 25% peptone yeast-extract agar (GPYA) medium, and then incubated at 30oC for seven days. After that the colony was transferred on potato dextrose agar (PDA) and czapeks dox agar (CDA) identification media. The results indicated that there were 10 different kind of moulds can be found in all samples, namely Aspergillus flavus, A, niger, A. versicolor, A. fumigatus, Aspergillus sp., Monilia sp., Mucor sp., Penicillium sp., Rhizopus sp. and Wallemia sp. In order to examine the influence of sugar concentration on the growth of moulds, the candied salaks were treated in different concentration. Candied salak with or without additional benzoicacid were treated with sugar concentration of 200 g/l, 250 g/l and 300 g/l. The highest concentration of sugar showed to lowest diversity of moulds for varieties of sleman and gading, conversely for variety of salak pondoh, the additionalof high sugar concentration showed increase in their diversity. The diversity of moulds in day of seventh was smallerthan the diversity of moulds in day of null. The concentration of benzoic acid (1 g/l) confined the diversity of moulds.© 2002 Jurusan Biologi FMIPA UNS SurakartaKey words: candied salak, osmotic pressure, diversity of mould.

Solution properties of polystyrene–polybutadiene block copolymers

AbstractDilute solution viscosity and osmotic pressure measurements were performed on polystyrene (PS), polybutadiene (PB), polystyrene–polybutadiene (SB) diblock and polystyrene–polybutadiene (SBS) triblock copolymers. Anionic polymerization was used in such a way that the molecular weight of the PS block was kept constant (ca. 10 000), while the molecular weight of the PB block varied from 18000 to 450000. The measurements were carried out at a fixed temperature of 34.20°C in three solvents, namely toluene, a good solvent for PS as well as for PB, dioxane, which is a good solvent for PS and almost a theta solvent for PB, and cyclohexane, which is nearly a theta solvent for PS and a good solvent for PB. The compositions of SB and SBS, as derived from kinetic data agree with ultraviolet measurements in CHCl3 solutions. The viscosity and osmotic pressure results indicate that the properties of SB and SBS are similar. Their intrinsic viscosities and second virial coefficients can be calculated from their chemical compositions, molecular weight, properties of parent polymers, and values of the interaction parameter \documentclass{article}\pagestyle{empty}\begin{document}$\bar \beta _{{\rm SB}}$\end{document} between styrene and butadiene units, for molecular weights not exceeding approximately 105. The magnitude of \documentclass{article}\pagestyle{empty}\begin{document}$\bar \beta _{{\rm SB}} $\end{document} varies with the solvent. The results suggest that the domains of the PS and PB blocks overlap to a great extent.

Clinical Application of Cryoscopy

Since 1888 when Beckmann¹devised the first relatively sensitive apparatus for determining the freezing point of a solution, the medical use of this instrument, the cryoscope or osmometer, has been limited mainly to physiological and clinical research for measuring total solute concentration and osmotic pressure. However, determination of the freezing point of biological fluids also has routine clinical value in assessing certain fluid, electrolyte, and urinary abnormalities. <h3>Osmotic Pressure</h3> When two aqueous solutions of different solute concentrations are separated by a semipermeable membrane, water molecules will move from one solution into the other. This movement is related to the average energy per unit concentration of the water molecules and is referred to as the "escaping tendency," or as the chemical potential. When the chemical potentials of the water molecules of two solutions differ, there will be a net movement of water molecules from the solution with the higher chemical potential

The permeability of the cricket eggshell to water

When house-cricket eggs of any age are floated on a 2 M sucrose solution (osmotic pressure = 116·6 atm), water is removed only very slowly from the egg, and it is concluded that there is a barrier to water loss in the shell. The maternal endocuticle is negatively charged and the maternal epicuticle probably positively charged. The relative impermeability of the new-laid shell is attributed to imbibition pressure of the shell protein resisting the osmotic gradient. These results are discussed in relation to previous work on water absorption in cricket eggs.

Thermodynamics of Swelling. I. Thermodynamic Properties of Crosslinked Binary Systems

Abstract Part I of this article was devoted to the thermodynamic properties of binary-mixed phases, in which one component was a low-molecular-weight liquid and the other a polymer crosslinked by primary-valence bonds. Special attention was paid to the case where the macromolecular material is in a glassy state at the measurement temperature. When solvent concentrations are low, the mixed phases are also in the glassy state. If the freezing concentration is exceeded during isothermal absorption of liquid, elastic materials appear, stable as to form when swelled, which are designated gels. Like liquids, gels are in a state of internal equilibrium. When polymer components have primary-valence crosslinks, liquid take-up always leads to an equilibrium state (swelling maximum, saturated gel). The enthalpy-concentration diagram was investigated rather thoroughly. If the polymer is in internal equilibrium at the measurement temperature, then the heat of mixing (heat of swelling) arises only from interaction between molecules. On the other hand, if the pure polymer component is frozen, the negative heat of freezing is superposed upon the “genuine” heat of swelling, resulting from interaction. Even when the enthalpy of the mixed phase is an additive function of the values for the pure components, a heat of mixing appears which originates only from liberation of the heat of freezing. The sign of the limiting heat of dilution, i.e., the differential heat of dilution at the swelling maximum, determines the temperature dependence of the swelling equilibrium. In athermic systems, maximum swelling is independent of temperature. The osmotic swelling equilibrium was investigated thermodynamically. It was shown that swelling pressure in crosslinked systems corresponds to osmotic pressure in solutions. A survey of results from the statistical theory of crosslinked systems is presented using, as a basis, Flory's theory for an ideal-athermal gel. As with the thermodynamic treatment of low-molecular-weight systems, excess functions were also introduced here. For low-molecular-weight, liquid mixtures, the excess functions have reference to formulas for an ideal solution. For polymeric, crosslinked systems, however, the reference values suggested are the statistical equations for an ideal-athermal gel. Finally, limiting laws for infinite dilution are derived for a crosslinked, mixed phase.

Electrical measurements of immersed paint coatings on metal. II. Effect of osmotic pressure and ionic concentration of solution on paint breakdown

AbstractElectrical capacitance and electrode potential measurements have been used to study the behaviour of painted steel panels immersed in solutions of sucrose, of sodium chloride and other electrolytes, and in sea water.The water uptake of the paint in the early stages of immersion depends only on the osmotic pressure of the solution. The time to reach breakdown of the paint in sodium chloride solutions depends primarily on water uptake and secondarily on ionic concentration. The time to reach breakdown in sea water is considerably greater than that in sodium chloride solutions of similar ionic concentration. Corrosion rate after breakdown is primarily a function of the anodic‐cathodic pore resistance, which is related to the electrolytic conductivity of the ambient solution; it is decreased in concentrated solutions by diminishing oxygen solubility. A mechanism of the course of paint breakdown is suggested.

Sugar beet germination selection results in osmotic pressure solutions I. Germination methodology and osmotic selection effects on germination of four varieties

Sugar beet germination selection results in osmotic pressure solutions I. Germination methodology and osmotic selection effects on germination of four varieties

Sugar beet germination selection results in osmotic pressure solutions II. Yield and chemical constituents of progenies, on four varieties from osmotic selection

Sugar beet germination selection results in osmotic pressure solutions II. Yield and chemical constituents of progenies, on four varieties from osmotic selection

Filtration, diffusion, and molecular sieving through porous cellulose membranes.

1. A study has been made of the diffusion and filtration of a graded series of molecules (including tritium-labelled water, urea, glucose, antipyrine, sucrose, raffinose, and hemoglobin) in aqueous solution through porous cellulose membranes of three degrees of porosity. 2. Experimental results were in close agreement with predictions based on the membrane pore theory of Pappenheimer et al. (1,2). Restriction to molecular diffusion is a function of pore radius and molecular radius described by equation (11) in the text. Molecular sieving during ultrafiltration is a function of total pore area per unit path length, pore radius, molecular radius, and filtration rate given by equations (16) and (19). 3. Estimates of average pore radius made by means of this theory were considerably larger than estimates made by the method of Elford and Ferry (3) (Table II). Sources of error in the latter method are discussed and a new method of membrane calibration is proposed in which the total cross-sectional area of the pores is measured by direct diffusion of isotope-labelled water. 4. Steady-state osmotic pressures of solutions of sucrose and raffinose measured during molecular sieving through cellulose membranes were found to be close to the "ideal" osmotic pressures calculated by van't Hoff's law. Thus the present experimental data support the methods used by Pappenheimer et al. in their studies on living capillary walls as well as their theory of membrane pore permeability.

Polymer association. I. Osmotic pressure of solutions of mixed acidic and basic polymers

Polymer association. I. Osmotic pressure of solutions of mixed acidic and basic polymers

PERFORMANCE OF THE HEPP MICRO-OSMOMETER

Estimation of the molecular weight of horse serum albumin from the osmotic pressure of solutions containing 0.713 to 5.12 gm. per 100 cc. shows that the Hepp osmometer yields the same values as the standard simple osmometer of Adair. Accuracy and precision of the instrument decrease noticeably at concentrations of albumin less than 0.7 gm. per 100 cc. A determination in duplicate can be carried out with this instrument in less than 2 hours. The instrument is easily operated.

150. The osmotic pressure of solutions of polysaccharide derivatives. Part II. The osmotic pressure of derivatives of lichenin, inulin, glycogen, starch, and starch dextrin

150. The osmotic pressure of solutions of polysaccharide derivatives. Part II. The osmotic pressure of derivatives of lichenin, inulin, glycogen, starch, and starch dextrin

ON THE INFLUENCE OF AGGREGATES ON THE MEMBRANE POTENTIALS AND THE OSMOTIC PRESSURE OF PROTEIN SOLUTIONS

1. It is shown that when part of the gelatin in a solution of gelatin chloride is replaced by particles of powdered gelatin (without change of pH) the membrane potential of the solution is influenced comparatively little. 2. A measurement of the hydrogen ion concentration of the gelatin chloride solution and the outside aqueous solution with which the gelatin solution is in osmotic equilibrium, shows that the membrane potential can be calculated from this difference of hydrogen ion concentration with an accuracy of half a millivolt. This proves that the membrane potential is due to the establishment of a membrane equilibrium and that the powdered particles participate in this membrane equilibrium. 3. It is shown that a Donnan equilibrium is established between powdered particles of gelatin chloride and not too strong a solution of gelatin chloride. This is due to the fact that the powdered gelatin particles may be considered as a solid solution of gelatin with a higher concentration than that of the weak gelatin solution in which they are suspended. It follows from the theory of membrane equilibria that this difference in concentration of protein ions must give rise to potential differences between the solid particles and the weaker gelatin solution. 4. The writer had shown previously that when the gelatin in a solution of gelatin chloride is replaced by powdered gelatin (without a change in pH), the osmotic pressure of the solution is lowered the more the more dissolved gelatin is replaced by powdered gelatin. It is therefore obvious that the powdered particles of gelatin do not participate in the osmotic pressure of the solution in spite of the fact that they participate in the establishment of the Donnan equilibrium and in the membrane potentials. 5. This paradoxical phenomenon finds its explanation in the fact that as a consequence of the participation of each particle in the Donnan equilibrium, a special osmotic pressure is set up in each individual particle of powdered gelatin which leads to a swelling of that particle, and this osmotic pressure is measured by the increase in the cohesion pressure of the powdered particles required to balance the osmotic pressure inside each particle. 6. In a mixture of protein in solution and powdered protein (or protein micellae) we have therefore two kinds of osmotic pressure, the hydrostatic pressure of the protein which is in true solution, and the cohesion pressure of the aggregates. Since only the former is noticeable in the hydrostatic pressure which serves as a measure of the osmotic pressure of a solution, it is clear why the osmotic pressure of a protein solution must be diminished when part of the protein in true solution is replaced by aggregates.

Errata: The Influence of Ions on the Osmotic Pressure of Solutions

Errata: The Influence of Ions on the Osmotic Pressure of Solutions

The Influence of Ions on the Osmotic Pressure of Solutions

The Influence of Ions on the Osmotic Pressure of Solutions

The Influence of Ions on the Osmotic Pressure of Solutions

The Influence of Ions on the Osmotic Pressure of Solutions

On the osmotic pressures of aqueous solutions of calcium ferrocyanide. Part I. Concentrated solutions

In the following communication the experiments on the direct measurement of the osmotic pressures, on the vapour pressures, and on the densities have been carried out in conjunction with Mr. E. G. J. Hartley,those on the compressibilities with Dr. C. V. Burton. In the ‘ Proceedings of the Royal Society,’ Series A, vol. 77 (1906), pp. 156-169,Mr.Hartley and I gave a preliminary account of the determination of the osmotic pressures of strong aqueous solutions of cane sugar by means of measurements of the relative lowering of their vapour pressures as compared to that of water. We deduced a formula for the connection between the vapour and osmotic pressures of a solution, which, in view of the experimental errors, justified the neglect of corrections due to the compression of the solution and of the solvent. Since then Prof. A. W. Porter (‘ Proc. Roy. Soc.,’ A, vol. 79, 1907) has put forward an exact equation in which the influence of these two factors can be taken into account; increased experience with, and further modifications of, the vapour-pressure apparatus apparently justified the belief that the experiments would be more accurate, and therefore it seemed advisable to end endeavour to obtain complete data for the aqueous solutions of some one substance, so as to test the practical applicability of the new formula in its entirety.

XXXII. On a relation between the surface-tension and osmotic pressure of solutions

XXXII. <i>On a relation between the surface-tension and osmotic pressure of solutions</i>