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Measuring detergency of oily soils in the vicinity of phase inversion temperatures of commercial nonionic surfactants using an oil‐soluble dye
Author(s) -
Goel Satish K.
Publication year - 1998
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-998-0023-5
Subject(s) - chemistry , pulmonary surfactant , ethylene oxide , surface tension , phase inversion , hexadecane , soil water , salting out , electrolyte , chemical engineering , chromatography , organic chemistry , membrane , polymer , thermodynamics , aqueous solution , biochemistry , physics , environmental science , electrode , soil science , engineering , copolymer
We have used a simple technique to measure the detergency of model oily soil from 63∶35 blended polyester/cotton fabrics using solutions of commercial linear lauryl alcohol ethoxylates in the vicinity of their phase inversion temperatures (PIT). The method involves incorporation of an oil‐soluble dye in the oily soil, and measurement of reflectance at an appropriate wavelength directly on the fabric before and after wash. This technique was validated for our systems, and it provides an additional visual cue for the efficiency of soil removal. Hexadecane, which represents the linear hydrocarbon part of sebum (typical soil encountered in detergency) and has been widely studied in the literature, was used as the model oily soil. Maximal detergency occurs as a function of washing temperature at approximately 35, 62, and 80°C for ethoxylates with four, five, and six moles of ethylene oxide (C 12 EO 4 , C 12 EO 5 , and C 12 EO 6 ), respectively. The oil/water interfacial tension, measured using the spinning drop method, exhibits corresponding minima and complements the detergency results. Addition of sodium carbonate, a salting‐out electrolyte, decreases the optimal detergency temperature (ODT) of C 12 EO 5 , shifting its behavior toward C 12 FO 4 whereas addition of anionic surfactant increases the ODT of C 12 FO 5 , mimicking the behavior of a higher ethoxylate.