Peptization, cause

In reverse, the surfactant precipitates from solution as a hydrated crystal at temperatures below 7k, rather than forming micelles. For this reason, below about 20 °C, the micelles precipitate from solution and (being less dense than water) accumulate on the surface of the washing bowl. We say the water and micelle phases are immiscible. The oils re-enter solution when the water is re-heated above the Krafft point, causing the oily scum to peptize. The way the micelle s solubility depends on temperature is depicted in Figure 10.14, which shows a graph of [sodium decyl sulphate] in water (as y ) against temperature (as V). 

F. S. Brown and C. R. Bury 6 obtained colloidal solutions of phosphorus pentoxide in nitrobenzene by stirring the mixture in the presence of alcohols or organic acids. The hydroxy-compound is absorbed and peptizes the pentoxide. Traces of moisture cause coagulation. Cone. soln. set to gels on keeping. 

It seemed wise, therefore, to make preliminary experiments with sodium thiocyanate, NaCNS, because the sodium ion is not especially toxic and the thiocyanate ion is very effective in causing the peptization of proteins. The difference in action between sodium and potassium thiocyanate is apparently very great. We have injected 30 cc. of a 20% sodium thio-... 

Another example of subdivision/dispersion is given by the classic disintegration of metals that occurs when two electrodes of the same metal are submersed and subjected to an electric potential that causes arcing (Bredig s arc). Here, metal melts at the electrode tips and becomes dispersed into suspension. Such suspensions can be stabilized by the presence of peptizing electrolyte. 

The fifth case was one of cocaine and morphine addiction. Here again the peptizing agent, sodium bromide, functioned as the theory predicts that it should and a ciure resulted. With his sixth patient MacLeod was not so fortunate, for the man, a doctor, died of pneumonia during the treatment that this was the cause of death was ascertained by a post-mortem examination. A case of mania and acute neurasthenia was ciured during a treatment with sodium bromide. The author is not absolutely sure that the sodium bromide caused the cure. This was followed by a case of uncontrolled neurasthenic vomiting which was apparently cured by the bromide treatment. 

Activated carbon will remove much of the pink color from commercial solutions of potassium hydroxide, sodium hydroxide, and sodium carbonate. Carbon is also useful for removing impurities that cause foaming. At times, difficulty is experienced in completely separating the carbon from caustic solutions because of a peptizing action. 

The peptization capabilities of polyphosphates depend on their sorption on aluminosilicates and colloidal particles of hydrated oxides of iron, aluminium and manganese. In practice, this causes problems in water treatment by coagulation when already rather low concentrations of polyphosphates can cause improper agglomeration of colloidal particles into sedimentable floccules. 

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