Sodium sulphate solutions, attack

Nickel-iron alloys are more resistant than iron to attack by solutions of various salts. In alternate immersion tests in 5% sodium chloride solution Fink and De Croly determined values of 2-8, 0-25 and 0-5 g m d for alloys containing 37, 80 and 100% nickel compared with 46 g m d for iron. Corrosion rates of about 0.4 g m d are reported by Hatfield for Fe-30Ni alloy exposed to solutions containing respectively 5 Vo magnesium sulphate, 10 Vo magnesium chloride and 10% sodium sulphate the same alloy corroded at a rate of about 1.2 g m d in 5% ammonium chloride. 

Sulphur dioxide and sulphurous gases attack basic rocks and glasses superficially at high temperatures (900° C.) with the formation of water-soluble sulphates, chiefly sodium sulphate.3 It is probable that such reaction and the solution of the products in hot springs during the early post-volcanic period explain the origin of alkaline sulphated thermal waters. 

For example, a solution of sodium sulphate, when electrolysed between a copper anode and a platinum cathode, furnishes S04 ions at the anode which attack the copper and produce copper sulphate simultaneously, sodium hydroxide is formed at the cathode by the interaction of the water with the discharged sodium. The two substances react, and copper hydroxide is precipitated. 

In solution, they can provoke a slight, uniform attack of aluminium at room temperature. The dissolution rate is in the order of 0.01 mm per year in a solution of 10% sodium sulphate. The intensity of the attack does not increase with temperature, but superficial pitting occurs at a temperature of 50 °C and higher [10]. 

The production of such substances as white lead, lead sulphate, oxides, hydroxides, and sulphides of the heavy metals, can be effected by the electrolysis of a suitable solution, such as sodium (or potassium) nitrate, chloride, or sulphate, with an attackable anode and a cathode of platinum or some metal not attacked by the electrolyte. 

Monazite concentrate is processed either with sulfuric acid, like bastnasite, to produce a mixture of sulfates but the usual process is an alkaline treatment. The alkali process is preferred since it removes the phosphates more readily [9]. Whichever method is chosen the radioactive thorium must be completely removed. After benefication the monazite concentrate is finely ground and reacted with a hot concentrated sodium hydroxide at 140° to 150°C. Insoluble hydroxides of the rare-earths and thorium are formed while trisodium phosphate and excess sodium hydroxide remain in solution. The next step is hydrochloric acid attack on the solids portion. The thorium remains insoluble and a crude thorium hydroxide can be filtered off Trace contaminants that do carry through into solution, such as uranium and lead, as well as some thorium, are removed by coprecipitation with barium sulphate in a deactivation step. The cerium-containing product will be a rare-earth chloride differing only marginally in the proportions of the various rare- earths present, to the analogous rare-earth chloride produced from bastnasite. 

AMMONIUM SULPHATE (7783-20-2) H8N2O4S Noncombustible solid. Aqueous solution is a strong acid. Violent reaction with fused potassium chlorate potassium nitrite. Reacts with caustics, forming ammonia. Hot material reacts with nitrates, nitrites, chlorates. Incompatible with strong oxidizers sulfuric acid aliphatic amines alkanolamines, amides, organic anhydrides isocyanates, vinyl acetate aUcylene oxides epichlorohydrin. Mixture with sodium hypochlorite forms nitrogen trichloride, an unstable explosive material. Attacks metals in the presence of moisture. 

The stability of the non-ionic surfactant, sucrose monolaurate, below and above its CMC has been studied. Below the CMC first-order kinetics are observed for its hydrolysis to lauric acid, but this is not so above the CMC. In buffered systems at a pH when the lauric acid is ionized, the product of hydrolysis appears to form mixed micelles with the sucrose monolaurate, producing negatively charged micelles which appear to protect the ester from attack and thus reduce rates of hydrolysis [155]. Sodium dodecyl sulphate is more stable to hydrolysis in alkaline solutions above its CMC than in acid solutions where the rate of hydrolysis is proportional not only to the hydrogen ion concentration, but also to the concentration of the detergent itself [156]. This agrees with the observation of Kurz [157] that the proton-catalysed rates of hydrolysis of mono-... 

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