Studies on the mechanism of coagulation

Mathai, K. G.; Ottewill, R. H.

doi:10.1007/bf01882350

Cited by 18 publications

(3 citation statements)

References 9 publications

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“…Surfactant molecules, being adsorbed on colloid particles, evidently cause hydrophilization of their surface (see also ref. (7), (8)). This is indicated, in particular, by the reversible nature of coagulation-on shaking up the coagulate with water the precipitate is practically completely peptized.…”

Section: -mentioning

confidence: 99%

Effect of surface-active agents on stability of hydrophobic sols

Glazman¹

1966

Discuss. Faraday Soc.

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The aggregative stability of colloidal solutions arises from the presence of a barrier preventing proximity of the particles, which is caused by the presence of repulsion, as well as attraction between these particles. Colloidal systems of two types-lyophobic and lyophilic-are formed, depending on the nature of the repulsion forces. By non-ionogenic surface-active agents (SAA) hydrophobic sols are converted into hydrophilic. This transition, manifested in an extremely sharp rise in the resistance of the system to the effect of electrolytes, is realized at fairly low SAA concentrations, which depend on the nature and content of the colloidal disperse phase and on the structure of the surfactant.The author's experimental data permit some inferences to be drawn as to the nature of the phenomena occurring on stabilization of colloidal solutions by means of SAA and the mechanism of breaking lyophilic sol stability in highly concentrated electrolyte solutions. The surfactant molecules, adsorbed on colloid particles, cause hydrophilization of their surface. Highly concentrated electrolyte solutions cause disturbance of polymolecular solvate layers at the particle surface, thus allowing the colloidal system to coagulate.* With a positive silver iodide sol the sensibilization attains the highest limit; the surfactants cause coagulation of the colloidal solution without addition of electrolytes. t During sol coagulation by electrolytes with bi-and tri-valent counter-ions (calcium and lanthanum salts) such slight surfactant additions had no effect on the stability, * Electrophoresis shows that colloidal particles in SAA-protected systems move in an electric field.

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Section: -mentioning

confidence: 99%

Effect of surface-active agents on stability of hydrophobic sols

Glazman¹

1966

Discuss. Faraday Soc.

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“…Likewise, the mode of adsorption of nonionic detergents at the liquid/solid interface has been investigated by Mathai and Ottewill using homogeneous materials (31). The effects of a honlologous series of n-alkyl hexaoxyethylene glycol monoethers on the formation of positively or negatively charged silver iodide sols have been studied in the presence and absence of inorganic flocculating ions.…”

Section: Detergency and Dispersionmentioning

confidence: 99%

Physical chemistry of nonionic detergents

Schick¹

1963

J Americ Oil Chem Soc

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“…5 Their preparation and characterization has now made it possible to examine their mode of interaction with solid surfaces and hence their effect on sol stability and the formation of sols. 6 The protection of lyophobic sols by the adsorption of macromolecules has been studied by a number of authors.7-10 Quantitatively, such a system is difficult to interpret until more is known about the adsorption of macromolecules at interfaces and the average spatial extension of the molecule from the surface. The use of a non-ionic detergent, however, provides an alternative means of coating a sol particle with an adsorbed lyophilic layer .11 In this communication the effect of a number of polyoxyethylene glycol monoalkyl ethers on the electrophoretic properties of silver iodide sols and suspensions, in the absence and presence of flocculating agents, are described.…”

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confidence: 99%

Stability of hydrophobic sols in the presence of non-ionic surface-active agents. Part 1.—Electrokinetic and adsorption measurements on silver iodide sols and suspensions

Mathai¹,

Ottewill²

1966

Trans. Faraday Soc.

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The electrophoretic mobility of sols and suspensions of silver iodide has been investigated in the presence of a series of homogeneous non-ionic detergents of the alkyl polyoxyethylene glycol monoether type. Just before the critical micelle concentration of the non-ionic detergent was reached a pronounced decrease in the mobility of the particles was observed. Adsorption isotherms of the alkyl hexaoxyethylene glycol monoethers on silver iodide powder also showed a pronounced increase in adsorption in the same concentration region. The changes were consistent with the formation of a multilayer of non-ionic detergent on the surface which caused a displacement of the electro-kinetic plane of shear away from the surface. Adsorption of non-ionic detergent at the silver iodide/solution interface inhibited the adsorption of lanthanum, barium and sulphate ions.

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Studies on the mechanism of coagulation

Cited by 18 publications

References 9 publications

Effect of surface-active agents on stability of hydrophobic sols

Effect of surface-active agents on stability of hydrophobic sols

Physical chemistry of nonionic detergents

Stability of hydrophobic sols in the presence of non-ionic surface-active agents. Part 1.—Electrokinetic and adsorption measurements on silver iodide sols and suspensions

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