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A test method for analyzing anionic or cationic surfactants in industrial water
Author(s) -
Wang L. K.
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/bf02639191
Subject(s) - cationic polymerization , pulmonary surfactant , titration , chemistry , ammonium , reagent , ammonium chloride , inorganic chemistry , organic chemistry , biochemistry
A general 2‐phase titration method is introduced for the quantitative identification of either anionic or cationic surface active agents commonly used in the domestic and industrial applications. Initially, an appropriate amount of quaternary ammonium compound is added to an unknown water sample to be analyzed and to ensure the treated sample contains excess amount of quaternary ammonium compound, and thus, is cationic in nature. The amount of excess quaternary ammonium compound is then quantitatively determined by titration with a standard anionic surfactant in the presence of methyl orange dye, buffer reagent, and chloroform. If the original surfactant in the tested sample is anionic, the anionic surfactant content (μM) is equal to the known amount (μM) of the added cationic quaternary ammonium compound minus the amount (μM) of standard anionic titrant spent in the neutralization reaction. If the original surfactant in the tested sample is cationic, the cationic surfactant content (μM) is equal to the amount (μM) of standard anionic titrant spent in the titration minus the known amount (μM) of the added cationic quaternary ammonium compound. The test procedure is simple and can be successfully completed within 5–7 min by a laboratory technician. For research or industrial application, a specific anionic or cationic surfactant to be used should be selected for the surfactant calibration. For the water quality control of unknown samples, the most common anionic surfactant, linear alkylate sulfonate, and the most common cationic surfactant, quaternary ammonium chloride, are selected as surfactant standards. The anionic surfactant concentration of a sample can be reported to be mg/liter as linear alkylate sulfonate while the cationic surfactant concentration of a sample can be reported to be mg/liter as cetyldimethylbenzylammonium chloride. Other alternatives for the use of the proposed general 2‐phase titration method are suggested. Effective elimination of the interference caused by the presence of oil in an industrial water is also discussed. The proposed method is limited in application to the measurement of free ionic surface active agents only.