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Surface pH and stability of oil‐water emulsions derived from laurate solutions
Author(s) -
Saleeb Fouad Z.,
Cante Charles J.,
Streckfus Thomas K.,
Frost John R.,
Rosano Henri L.
Publication year - 1975
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02672172
Subject(s) - lauric acid , chemistry , cyclohexane , emulsion , hexadecane , surface tension , inorganic chemistry , potassium , analytical chemistry (journal) , chemical engineering , chromatography , organic chemistry , thermodynamics , fatty acid , physics , engineering
Emulsion stability, electrophoretic mobility, and interfacial tension of chloroform, cyclohexane, and n‐hexadecane‐potassium laurate solution were determined as a function of acidification by concentrated HCl. The stability of these emulsions were related to the presence or absence of lauric acid at the interface. It was found that a lauric acid‐laurate interfacial film was responsible for the enhanced stability in the case of cyclohexane and n‐hexadecane emulsions, while no such mixed film existed in the case of chloroform. The interfacial ionization markedly affects the distribution of ions in solution closer to the interface. The concept of surface pH was applied. Differences of up to 2 pH units between bulk and surfaces were found with these systems. Both cyclohexane and hexadecane have major stability peaks which lie at ca. the same surface pH of 5.9 ± 0.2, irrespective of the initial potassium laurate concentration or bulk pH. It is concluded that the stability of these emulsions can be explained when the role played by the interfacial ionization is taken into consideration.