Electrolyte solutions fluids

Lin, Ch.L. and Lee, L.S., A two-ionic-parameter approach for ion activity coefficients of aqueous electrolyte solutions, Fluid Phase Equilibria, 205, 69, 2003. 

Maurer, G., Electrolyte Solutions, Fluid Phase Equilibria, 13, 269-296, 1983. 

O Connell, J. P. 1993. Application of fluctuation solution theory to strong electrolyte-solutions. Fluid Phase Equilibria. 83, 233. 

Held C, Cameretti LF, Sadowski G (2008) Modeling aqueous electrolyte solutions. Fluid Phase Equilib 270 87-96... 

Maurer G (1983) Electrolyte solutions. Fluid Phase Equil 13 269-293... 

Seyfkar N, Ghotbi C, Taghikhani V, Azimi G. (2004) Application of the nonprimitive MSA-based models in predicting the activity and the osmotic coefficients of aqueous electrolyte solutions. Fluid Phase Equilibr 22 189-196. 

The electrolyte solution is modelled as a two-component, electroneutral system of point ions with charges ez, = ezL = ez. The density of the fluid is (p+ = pL = p /2). The fluid-fluid and fluid-matrix Coulomb interactions are... 

Siemes and Weiss (SI4) investigated axial mixing of the liquid phase in a two-phase bubble-column with no net liquid flow. Column diameter was 42 mm and the height of the liquid layer 1400 mm at zero gas flow. Water and air were the fluid media. The experiments were carried out by the injection of a pulse of electrolyte solution at one position in the bed and measurement of the concentration as a function of time at another position. The mixing phenomenon was treated mathematically as a diffusion process. Diffusion coefficients increased markedly with increasing gas velocity, from about 2 cm2/sec at a superficial gas velocity of 1 cm/sec to from 30 to 70 cm2/sec at a velocity of 7 cm/sec. The diffusion coefficient also varied with bubble size, and thus, because of coalescence, with distance from the gas distributor. 

The composition of body fluids remains relatively constant despite the many demands placed on the body each day. On occasion, these demands cannot be met, and electrolytes and fluids must be given in an attempt to restore equilibrium. The solutions used in the management of body fluids discussed in this chapter include blood plasma, plasma protein fractions, protein substrates, energy substrates, plasma proteins, electrolytes, and miscellaneous replacement fluids. Electrolytes are electrically charged particles (ions) that are essential for normal cell function and are involved in various metabolic activities. This chapter discusses the use of electrolytes to replace one or more electrolytes that may be lost by the body. The last section of this chapter gives a brief overview of total parenteral nutrition (TPN). 

Combined electrolyte solutions are available for oral and IV administration. The IV solutions contain various electrolytes and dextrose. The amount of electrolytes, given as milliequivalents per liter (mEq/L), also varies. The IV solutions are used to replace fluid and electrolytes that have been lost and to provide calories by means of their carbohydrate content. Examples of IV electrolyte solutions are dextrose 5% with 0.9% NaCl, lactated Ringer s injection, Plasma-Lyte, and 10% Travert (invert sugar—a combination of equal parts of fructose and dextrose) and Electrolyte No. 2. 

Oral electrolyte solutions contain a carbohydrate and various electrolytes. Examples of combined oral electrolyte solutions are Pedialyte and Rehydralyte. Oral electrolyte solutions are most often used to replace lost electrolytes, carbohydrates, and fluid in conditions such as severe vomiting or diarrhea... 

For poly electrolyte solutions with added salt, prior experimental studies found that the intrinsic viscosity decreases with increasing salt concentration. This can be explained by the tertiary electroviscous effect. As more salts are added, the intrachain electrostatic repulsion is weakened by the stronger screening effect of small ions. As a result, the polyelectrolytes are more compact and flexible, leading to a smaller resistance to fluid flow and thus a lower viscosity. For a wormlike-chain model by incorporating the tertiary effect on the chain... 

The hole correction of the electrostatic energy is a nonlocal mechanism just like the excluded volume effect in the GvdW theory of simple fluids. We shall now consider the charge density around a hard sphere ion in an electrolyte solution still represented in the symmetrical primitive model. In order to account for this fact in the simplest way we shall assume that the charge density p,(r) around an ion of type i maintains its simple exponential form as obtained in the usual Debye-Hiickel theory, i.e.,... 

Electrochemistry is, with its combination of simple fluids and ions, a natural area of application for the GvdW theory. Here there is an obvious need to understand both the short-range fluids, the long-range electrolyte solutions and their properties in bulk and at interfaces. We hope this review can provide a useful tool for electrochemists and many others with communal interests and stimulate further progress in a field rich in fluid phenomena and mechanisms. 

The contribution of transport under the influence of the electric field (migration), which, if appreciable, should be subtracted from the total mass flux. The use of excess inert (supporting) electrolyte is recommended to suppress migration effects. However, it should be remembered that this changes the composition of the electrolyte solution at the electrode surface. This is particularly critical in the interpretation of free-convection results, where the interfacial concentration of the inert as well as the reacting ions determines the driving force for fluid motion. 

Different reaction mechanisms can predominate in fluids of differing composition, since species in solution can serve to promote or inhibit the reaction mechanism. For this reason, there may be a number of valid rate laws that describe the reaction of a single mineral (e.g., Brady and Walther, 1989). It is not uncommon to find that one rate law applies under acidic conditions, another at neutral pH, and a third under alkaline conditions. We may discover, furthermore, that a rate law measured for reaction with deionized water fails to describe how a mineral reacts with electrolyte solutions. 

There is no certainty, furthermore, that the reaction or reaction mechanism studied in the laboratory will predominate in nature. Data for reaction in deionized water, for example, might not apply if aqueous species present in nature promote a different reaction mechanism, or if they inhibit the mechanism that operated in the laboratory. Dove and Crerar (1990), for example, showed that quartz dissolves into dilute electrolyte solutions up to 30 times more quickly than it does in pure water. Laboratory experiments, furthermore, are nearly always conducted under conditions in which the fluid is far from equilibrium with the mineral, although reactions in nature proceed over a broad range of saturation states across which the laboratory results may not apply. 

Concentrations of electrolytes in body fluids and in pharmaceutical solutions are usually expressed as mEq/L or Eq/L. In institutional practice, various electrolyte solutions are administered to correct electrolyte imbalances. The doses of electrolytes are calculated either in milliequivalents or in metric weights. 

The instrument constant B can be determined by measuring the t in two fluids of known density. Air and water are used by most workers (22). In our laboratory we used seawater of known conductivity and pure water to calibrate our vibrating flow systems (53). The system gives accurate densities in dilute solutions, however, care must be taken when using the system in concentrated solutions or in solutions with large viscosities. The development of commercial flow densimeters has caused a rapid increase in the output of density measurements of solutions. Desnoyers, Jolicoeur and coworkers (54-69) have used this system to measure the densities of numerous electrolyte solutions. We have used the system to study the densities of electrolyte mixtures and natural waters (53,70-81). We routinely take our system to sea on oceanographic cruises (79) and find the system to perform very well on a rocking ship. 

Mixed aqueous electrolyte solutions such as body fluids, rivers, lakes, oceans and, at times, laboratory and industrial fluids present important problems which are not found 1n single electrolyte solutions. New perceptions and results are being obtained in complex media and some examples will be covered in this paper. 

Note - Some products such as amino acid solutions and multiple electrolyte solutions containing dextrose will not be brought to near physiologic pH by the addition of sodium bicarbonate neutralizing additive solution. This is due to the relatively high buffer capacity of these fluids. 

The majority of blood substitutes currently in use function only as plasma expanders. These maintain blood pressure by providing vascular fluid volume after haemorrhage, burns, sepsis or shock. While standard electrolyte solutions, such as physiological saline, may be administered, their elfect is transitory as they subsequently dilfuse back out of the vascular system. 

It is obtained from heat treated pooled human plasma. 100 ml of 20% human albumin solution is osmotic equivalent of 800 ml of whole blood. It draws and holds additional fluid from tissues. It can used irrespective of patient s blood group. For optimum benefit it should be used with electrolyte solutions. It does not interfere with coagulation and there is no risk of sensitization. 

Magnesium salts, e.g. magnesium sulphate (Epsom salt), sodium phosphates, and polyethylene glycol-electrolyte solutions, produce largely fluid stools, and are useful in pre-operative preparation of the bowel. 

Although HPMC is not thought itself to be pH sensitive [6], the pH of a dissolution fluid is known to affect release rates of drugs from its matrices via the suppression of ionization [7]. The cloud points at 2% K100 gels (Table 1) were only affected by pH at low pHs. It was therefore considered unnecessary to modify the pH of electrolyte solutions used to determine cloud points. 

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