Sulphate and chloride

Stainton [31] has described an automated method for the determination of sulphate and chloride in non saline waters. An ion exchange resin is used to convert the sulphates and chlorides to their free acids. Detection is achieved by electrical conductance. The use of silver-saturated cation exchange resin to precipitate chloride permits distinction between 

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This reaction is also used on a large scale, to obtain iodine from seaweed. The ash from burnt seaweed ( kelp ) is extracted with water, concentrated, and the salts other than iodides (sulphates and chlorides) crystallise out. The more soluble iodides remain and the liquor is mixed with sulphuric acid and manganese dioxide added the evolved iodine distils off and is condensed. 

The subject is also closely related to fuel-ash corrosion which in most cases is caused by a layer of fused salts such as sulphates and chlorides Attention has been focused on the electrochemistry of this type of corrosion and the relevant thermodynamic data summarised in the form of diagrams . Fluxing and descaling reactions also resemble in some respects reactions occurring during the corrosion of metals in fused salts. A review of some of the more basic concepts underlying corrosion by fused salts (such as acid-base concepts and corrosion diagrams) has appeared. ... 

Soluble sulphates and chlorides in brickwork, plaster and other walling materials provide a more serious source of corrosion under damp condi-... 

In electrolytes containing both sulphate and chloride ions, the sulphate ion favours the formation of lead sulphate which is rapidly transformed to lead dioxide. The continuing satisfactory operation of the anode depends upon the initial conditions of polarisation. The lead dioxide is of better quality and more adherent when formed below 108 Am in solutions containing higher sulphate concentrations or when the water is agitated" . 

Sulphates and chlorides are present in industrial and marine atmospheres. In water they accelerate the corrosion of steel. Avoiding lodgement areas for water and dirt reduces the risk of the latter acting as a poultice in which the corrosive salts can build up. 

Contact corrosion may be reduced by the presence of natural inhibitors, such as tannins, in the wood, and will be promoted by sulphates and chlorides in it, especially if mineral preserving processes involving these ions have been applied. 

Both sulphate and chloride ions were found to accelerate the reaction under constant ionic strength conditions and, although medium effects may operate, pathways involving chloride and sulphate ions are possible. For the sulphate ion addition Newton and Baker conclude that the step... 

The anomalous features are observed on well-ordered (111) surfaces in a variety of electrolytes over a wide range of pH (0-11), but the potentials at which the features appear and the detailed shapes of the I-V curves vary considerably. Specifically, the potential region (versus RHE) in which the features appear changes with anion concentration in sulphate and chloride electrolytes, but not in fluoride, perchlorate, bicarbonate or hydroxide electrolyte. In sulfate electrolyte, at constant anion concentration the region shifts (versus RHE) with varying pH, while in fluoride, perchlorate, bicarbonate and hydroxide electrolyte it does not. The use of UHV surface analytical techniques has established to a reasonable (but not definitive) extent that adventitious impurities are not involved in the anomalous process, i.e., the only species participating in the chemistry are protons/hydroxyIs, water and the anions of the solute. On the basis of the pH and anion concentration dependencies, I agree with the... 

Let us now extend the long-period hydronium ice-like model for the IHP on Pt(lll) to explain the observations in electrolytes other than sulphate. In acid chloride, both the observations and the model carry-over directly from the case of sulphate. In fluoride, perchlorate, bicarbonate and hydroxide, in Which the anomalous features shift considerably in both potential and appearance (especially in the basic media) from sulphate, another model is needed. Both (bi)sulphate and chloride are large weakly hydrated anions, and in the double-layer model of Figures 4-5, they interact strongly with both the hydronium ions and the Pt surface. The contact adsorption... 

Analytical Procedures. Mn was determined by atomic absorption spectrophotometry (AAS) or the formaldioxime method (27J. Ca, Mg and Fe were determined by AAS. Silicate, phosphate, sulphate and chloride were determined using techniques described in Standard Methods (28). The molybdosi1icate method was used for silicate. Phosphate was determined using the vanadomolybdophosphoric acid method. Sulphate was determined by BaSO gravimetry. Chloride was determined by the mercuric chloride method. Salicylate and phthalate were determined by UV spectrophotometry. 

The kelp is crushed into lumps—say, one to two inches diameter—and extracted with water in rectangular iron vats with false bottoms, heated by steam. The liquid of sp. gr. 1 200 to l-255 is decanted into open iron boiling pans where it is evaporated down to a sp. gr. of 1 325 the salts—mainly potassium sulphate (50-60 per cent.) mixed with sodium sulphate and chloride—which separate by crystallization during the evaporation are removed. The hot liquid is run into cooling vats where crystals of potassium chloride separate. The liquid is again boiled down, and crystals consisting mainly of sodium chloride with 8 to 10 per cent, of sodium carbonate—and called kelp salt-—separate from... 

Fig. 6. —Equilibrium Conditions of Mixtures of Magnesium and Potassium Sulphates and Chlorides—J. H. van t Hoff.

W. C. Blasdale has applied these results to show what takes place during the fractional crystallization by the evaporation of soln. containing different proportions of the component salts—the separation of (i) sodium and potassium chlorides (ii) potassium chloride and sulphate (iii) potassium and sodium sulphate (iv) sodium sulphate and chloride and of (v) potassium salts from mixtures of sodium and potassium chlorides and sulphates. The results were then extended to samples of desert brine. J. H. Hildebrand also showed how J. H. van t Hoff s results show the course of the fractional crystallization of sea-water containing magnesium, sodium, and potassium sulphates and chlorides. 

We have accordingly made a number of measurements on pyridinium salts. In agreement with Lord and Merhifteld [8] we find the broad structureless band at about 2460 cm 1 in the spectrum of pyridine hydrochloride in chloroform solution, which they attributed to Nh— Ho., Cl" bonding. In addition we find this raised to about 2570 cm 3 in ethanol solution. The solid perchlorate, sulphate and chloride (in KBr discs) have practically identical spectra (to 4 tu.) in which the broad band now occurs centred on 2740 cm 1. Pyridiniain perchlorate dissolved in pyridine shows a similar band at 2530 cm 3. This is presumably due to solvation of the pyridinium ion through —H N... 

It must bo remembered that this mode effects the bicarbonate of lime, not the more troublesome earthy salts, each as the sulphates and chlorides, on which the hardness of spring waters mainly depends. The diffi culty of mixing lime and watar, in definite proportions, on the large scale, must he obvious to every one. If toe much be employed, the. companies would supply their customers with litne- icater If too little, the bicarbonate of limo would not be completely destroyed, and the process would be a Failure. Altogether, the difficulties of carrying out the process Will ever prevent its adoption on a large scale. 

Sulphates and Chlorides. — Boil 0.5 gm. of potassium permanganate with a mixture of 2 cc. of 95 per cent alcohol and 25 cc. of water, and filter. The filtrate should be colorless, and, after adding to it 2 cc. of nitric acid, barium nitrate, and silver nitrate solutions, it should not develop more than a slight opalescence. 

Sulphates and Chlorides. On shaking 2 gm. of zinc oxide with 20 re. of water and filtering, the acidulated filtrate should show no reaction on the addition of barium nitrate Hohilioiu and should acquire at most a. slight opalescent turbidity on the addition of silver nitrate solution. 

These components are alcohol, glycerine, sugars, colouring matters, albuminoid and tannin substances, inorganic salts (phosphates, sulphates and chlorides of potassium, sodium, magnesium, calcium and aluminium), non-volatile organic acids (especially tartaric, malic, succinic and lactic, partly free and partly combined as salts), volatile acids (especially acetic) and esters, the latter being the source of the particular perfume or bouquet of the wine. 

They may contain as impurities, small quantities of alkali, sulphates and chlorides and are often adulterated with kaolin, heavy spar, gypsum, chalk, white lead, zinc white, magnesia, starch, etc. 

Impurities.—2 or 3 grams of the substance are treated with hot caustic soda solution, the liquid being diluted and filtered and the insoluble part washed and then dissolved in hot dilute sulphuric acid any undis solved residue may contain especially silica or silicates and barium sulphate, these being identified by the ordinary methods. The alkaline solution is tested for sulphates and chlorides. 

The colour of the ash, its solubility in hydrochloric acid, and its neutrality or alkalinity are noted a qualitative analysis may be made, with reference especially to the silica, alumina, ferric oxide, lime, magnesia, alkalies, phosphates, carbonates, sulphates and chlorides. 

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