Reducing Salts

The health-conscious trend toward development of fat replacements (see Eat replacers), reduced salt and MSG intake, and use of artificial sweeteners (qv) to reduce caloric intake has influenced the increase in spice usage. AH of these trends requite spices to compensate for flavor loss or to overcome a perceived or actual difference in flavor. 

Major problems inherent in general applications of RO systems have to do with (1) the presence of particulate and colloidal matter in feed water, (2) precipitation of soluble salts, and (3) physical and chemical makeup of the feed water. All RO membranes can become clogged, some more readily than others. This problem is most severe for spiral-wound and hollow-fiber modules, especially when submicron and colloidal particles enter the unit (larger particulate matter can be easily removed by standard filtration methods). A similar problem is the occurrence of concentration-polarization, previously discussed for ED processes. Concentration-polarization is caused by an accumulation of solute on or near the membrane surface and results in lower flux and reduced salt rejection. 

Reduzierbarkeit, /. reducibility. reduzieren, v.t. reduce. reduzierfaUg, a. capable of reduction. Reduzier-salz, n. reducing salt, -stiick, n. 

Salt Concentration. The most cost-effective method of reducing salt concentration levels is to dilute water-base drilling fluid with freshwater. Care must be taken to make sure that the makeup water is compatible with the system. The water must not contain high concentrations of undesirable corrodents. 

Electrochemical processes are particularly well suited for the manufacture of fine chemicals in view of their high sjjecificity (almost comparable to that offered by enzymes), the smaller number of steps required, adoption of milder conditions, lack of scale-up problems, avoidance of effluents, etc. The ease with which oxidation and/or reduction can be carried out with the practically mass-free clean electrons makes electrochemical processes well suited for such jobs, including paired synthesis in effect, we use electricity as a reagent . Consider a standard chemical oxidant like manganic or chromic sulphate. Here, a stoichiometric amount of the reduced salt will be formed the disposal of which can be a serious problem. If we adopt an electrochemical process, then the reduced salt is converted into the desired oxidized salt. 

Metallic powders are made several different ways. They can be prepared by reducing salts in a stream of a reducing gas, such as hydrogen chlorides of metals are commonly used but oxides are used too. Thermal decomposition in a vacuum of metal carbonyls or metal salts of organic acids, such as formates, produces metal powders. Surface areas of such powders are around 1.5 m2/g. Powders can also be made from electrolytic reduction of salts in organic solvents and by atomization of the metal. 

A mixture of these oxidising and reducing salts will explode violently after most of the water of crystallisation has been driven off by heating. 

Scheme 2.S-3. Reduced salts of diaryltin species (Ar =C6Hj-2,6-Trip2 Trip=C6H2-2,4,6-/-Pr3).

Reverse osmosis is now extensively used to reduce salt concentrations in brackish waters and to treat industrial waste water, for example, from pulp mills. Reverse osmosis has also proved economical (the cost can be as low as about 1 per 1000 liters) for large-scale desalination of seawater, a proposition of major interest in the Middle East, where almost all potable water is now obtained by various means from seawater or from brackish wells. Thus, at Ras Abu Janjur, Bahrain, a reverse osmosis plant converts brackish feedwater containing 19,000 ppm dissolved solids to potable water with 260 ppm dissolved solids at a rate of over 55,000 m3 per day, with an electricity consumption of 4.8 kilowatt hours per cubic meter of product. On a 1000-fold smaller scale, the resort community on Heron Island, Great Barrier Reef, Australia, obtains most of its fresh water from seawater (36,000 ppm dissolved salts) directly by reverse osmosis, at a cost of about 10 per 1000 liters. 

DGDN powder usually contained flash reducing salts. Their quantity was indicated by a figure following the letter denoting the calorific value, e.g. G.0. meant no salts are present, G 1,5 denoted 1.5% salts. 

Salts of Ordinary Oxygen Acids.—Among the ordinary oxygen salts are included the oxyhalogens the nitrates and the nitrites the carbonates the phosphates, phosphites, and hypophosphites the sulfates and sulfites the borates and the silicates. These may be divided into (a) oxidizing salts and (b) reducing salts. 

Neutralization.—The preparation of reducing salts by neutralization requires no special comment. The most familiar examples are the soluble sulfites and sulfides. Since these are salts of weak, dibasic acids, it is not satisfactory to rely upon indicators for neutrality. The usual procedure is to prepare a solution of the base and divide it into two equal parts. One of these is saturated with the acid, producing the acid salt, and the other portion is then added, with the formation of the normal salt (example, preparation of (NH4)2S as a laboratory reagent). 

Special Methods.—Many special methods are employed to produce reducing salts, particularly cathode reduction. The following exercise illustrates one of these special methods, viz., the action of a metal (zinc) on sulfur dioxide. 

Sulphurous acid reduces salts of gold, throwing down the gold in the metallic state. It is capable of taking up the second equivalent of oxygen from almost every metallic hinoxide.. ... 

Owing to reduced salt solubility, the formation of metal oxides and, eventually, the presence of stable solid-matter particles, these are all present in the SCWO processes. These particles can cause equipment-fouling and erosion. However the reduced solubility of salts under supercritical conditions introduces the possibility of a solid fluid separation. 

Nevertheless, the concern remains on the part of a large number of professional people who feel that someday a definitive correlation will be made. And, with considerable awareness of the lay public in this regard, very definite pressures are being exerted on food processors to reduce salt usage and to more accurately label thdr merchandise in this regard. 

The appropriate choice of organic counterion can result in reduced salt toxicity. There is evidence that salicylates may accumulate with chronic administration, which can be compounded if renal function is below normal (Lasslo et al., 1959). The nature and degree of absorption of tartrate from the human intestine has been questioned (Underhill et al., 1931 Pratt and Swartout, 1933), but the fact that several tartrates are reported to possess cathartic activity argues against substantial absorption from the intestinal tract (Lasslo et al., 1959), which cites Goodman and Gilman. 

Reduced salt intake also negatively effects the all important sodium-potassium pump. This is the mechanism the body uses to shuttle many nutrients into cells like those that all muscle fibers are composed of. (Gee, ya think ) This would therefore inhibit creatine and some amino acid structures from adequately transporting, as well as inhibit glycogen synthesis. 

The release of alkaline compounds is also an important factor in coal combustion. Most high-temperature corrosion problems in fossil fuel boilers are the result of salt melts (54,55). Alkali metal compounds volatilize from coal at the high temperatures of conventional combustion and subsequently condense on heat transfer surfaces. The lower temperatures of FBC are expected to reduce salt volatility, a fact that has been confirmed by Vogel et al. (16). 

Trimethylorthoformate 17 is a highly activated Cl building block and a formic acid equivalent which is commonly applied in organic condensation reactions. 17 can be produced on an industrial scale by two major routes. The first starts with chloroform and sodium methanolate, but produces 3 equiv. of sodium chloride as waste. The second route is based on the acidic methanolysis of cyanhydric acid, which also produces stoichiometric amounts of ammonium chloride. Despite the reduced salt waste, the use and handling of cyanhydric acid mean high safety costs. Therefore, anodic methoxylation of formaldehyde dimethylacetal (16) to... 

Ether sulphates show a strong salt effect - that is an increase in viscosity on addition of salt (or other electrolyte). The response to electrolyte (the salt curve ) can be very different between ether sulphates, even from different suppliers of the same product. Generally, the more soluble the surfactant, the lower the salt response but higher degrees of ethoxylation reduce salt response, as does branching in the alcohol as shown in Figure 4.20. 

Red phosphorus is less soluble than white in all solvents. In water and alcohol it is almost insoluble. It is somewhat soluble in ether and in hot acetic acid, from which it is reprecipitated by water. It is slightly soluble in phosphorus trichloride. These solubilities refer to the ordinary preparation, which, as shown on p. 32, usually contains residual quantities of the white form. Red phosphorus is able to reduce salts, especially those of the noble metals, in aqueous solution on boiling. Salts of mercury are reduced to the metal those of gold and silver give insoluble phosphides while ferric and stannic salts are reduced to ferrous and stannous respectively.5... 

Tab. 9.7 Influence of the water content on the specific impulse (in s) of oxidizing and reducing salt mixtures.

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