Osmotic Phenomena

D. C. Guell, H. Brenner. Physical mechanism of membrane osmotic phenomena. Ind Eng Chem Res 55 3004, 1996. 

Lord Ivelvin has pointed out that the similarity between the laws of gases and of dilute solutions carries with it no inference as to physical similarity between the states, although Boltzmann has developed a theory of osmotic phenomena which regards the pressure as due to a bombardment of the semipermeable wall by the molecules of dissolved solute, whilst it is subjected to equal and opposite forces by bombardment from the solvent molecules inside and outside. 

One potential mechanism by which polymers may stabilize shales is by reducing the rate of water invasion into the shale. The control of water invasion is not the only mechanism involved in shale stabilization [133] there is also an effect of the pol5maer additive. Osmotic phenomena are responsible for water transport rates through shales. 

As mentioned above, the primary focus of this chapter is on osmotic pressure and its basis in solution thermodynamics. We consider both classical and statistical thermodynamic interpretations of osmotic pressure. The next three sections are devoted to this. The last two sections describe osmotic effects in charged systems and a few applications of osmotic phenomena. 

We conclude the chapter with a discussion of the Donnan equilibrium and the thermodynamic behavior of charged colloids, particularly with respect to osmotic pressure and molecular weight determination (Section 3.5), and some applications of osmotic phenomena (Section 3.6). 

Because wrev is the maximum available work of any type, we can say from (5.53) that AG is the maximum available non-PV work. Here, available (or free ) refers to the idealized reversible limit in which no useful work is dissipated. Practically speaking, the major non-PV work of interest to chemists is the chemical energy (as manifested, for example, in electrochemical or osmotic phenomena), associated with the chemical potential terms that will be introduced in Chapter 6. 

Osmotic phenomena of considerable importance are found throughout the natural world. Osmosis also underlies many important medical and industrial applications, as will now be briefly summarized. 

Aside from chemical osmosis, we have also been studying electro-osmosis and streaming potential, i.e. electrical current due to an hydraulic gradient. Within the research project, experimental results have been obtained for these phenomena that will be compared with modelling data to eventually acquire a combined model for chemico-electro-osmotic phenomena in groundwater. 

Trivalent iron usually is precipitated from solution in the form of X-ray-amorphous brown precipitates, called amorphous, precipitated, or colloidal hydrate of Fe oxide. The freshly precipitated hydroxide contains a large amount of water, part of which forms hydroxyl groups, but the rest of the water may retain a certain independence, being bound to the hydroxide by adsorption, capillary, or osmotic phenomena. 

Sucrose the most common sweetener for its pleasant taste. It is widely used as a preservative of marmalades, syrups, and confitures. Osmotic phenomena are involved. Due to competition of microorganisms and preserved foodstuffs for water molecules, the microorganism tissues undergo plasmolysis. Aqueous solutions containing 30% sucrose do not ferment, and 60% of the solutions are resistant to all bacteria but Zygosac-charomyces. 

Osmotic phenomena related to the presence of polyelectrolytes govern to a significant extent the distribution of water and dissolved substances in living tissues, as well as the transport of these substances through various... 

Osmotic phenomena have been observed since the middle of the eighteenth century. The first experiments were conducted with animal membranes and it wasn t unitl 1867 that artificial membranes were employed. In the early 1950 s, research workers at the University of Florida demonstrated, with thick films, that cellulose acetate possessed unique salt and water transport properties which made it potentially attractive as a reverse osmosis desalination membrane. During the 1960 s, Loeb and others at the University of California at Los Angeles developed techniques to prepare cellulose acetate membranes with an economical water flux and salt rejection at moderate driving pressures. With this development, reverse osmosis became a practical possibility. 

Lysis of cells may occur with concomitant release of the contents of these cells. (Lysis refers to a process involving breakage of cell walls via one of several possible mechanisms, either naturally via viral infections or osmotic phenomena, or via human intervention in the form of treatment with enzymes, chemicals, or son-ication.) When lysis occurs, a microorganism may subsequently engage in a second growth phase (cryptic growth) if it is able to metabolize the cellular components released by lysis of other cells. 

The first report of osmotic phenomena by French Cleric Abbe Nollet [1] in 1748 might be considered the origin of membrane science. Nollet s work generated extensive interest in osmosis culminating ultimately in van t Hoffs [2] quantitative relationships in 1887. 

Figure 1.10 Osmotic phenomena. At osmotic equiiibrium, the osmotic pressure An) across the membrane is exactiy counterbaianced by the hydrostatic pressure AP) appiied to the concentrated soiution. Source [3].

For a thermally fully developed laminar flow, for a fixed dynamic and thermal boundary condition and by neglecting the fluid axial conduction, (Pe oo), viscous dissipation (Br = 0), the flow work fi = 0), and electro-osmotic phenomena (Sl=f = 0), the Nusselt number depends on the cross-sectional geometiy (through the Poiseuille number e) only. 

In this chapter, we will consider simple non-equilibrium phenomena involving two fluxes and two forces. Such a situation arises in membrane transport phenomena (e.g. thermo-osmotic and electro-osmotic phenomena) involving two sub-systems separated by a membrane. In Chapters 5 and 6, transport phenomena in two flux-two force systems in continuous systems without a membrane would be discussed. 

Chapter 4. Electro-osmotic Phenomena Electro-osmotic pressure ... 

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