Solubility of Mineral Salts in Binary Solvent Systems of Nonionic Surfactants and Water
Journal Title
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Issue Date
2015-04-10
Authors
McGarvey, Peter
Publisher
Keywords
Chemistry , AAS , Surfactant
Abstract
Polyethylene glycol (PEG) and many nonionic surfactants related to PEG are liquid at room temperature and possess benign properties including low vapor pressure, low toxicity, biodegradability, and high solvation power due to their amphiphilicity. We also observed an appreciable ability to solvate mineral salts in contrast to traditional organic solvents. Very little is known about the solubility of mineral salts in these surfactants. For these reasons we began a systematic solubility study of a variety of mineral salts in solutions of varying ratios of water and surfactant from neat surfactant to water rich compositions. Three different surfactant/water solvent systems were evaluated: PEG200/water, C_10E_6/water, and C_10E_7P_2/water. Solubility measurements were taken for NaCl, KCl, KBr, CsCl, K_2HPO_4 and K_2SO_4 using atomic absorption spectroscopy. The solubilities decreased with decreasing water content but remained appreciably high in the neat surfactants, on the order of 10 mmolal for K_2SO_4 to 1 molal for KBr. Some salt solutions underwent phase separation or formed gels at particular water content levels.