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Did you know? ... Oil and water do mix after all
We all know that oil and water don’t mix. Either we have to shake them vigorously to make an emulsion, or we have to add a surfactant or detergent.
But in 2003, Professor Ric Pashley, then at the Australian National University, discovered that simply degassing water is enough to get water and oil to mix.
Water naturally contains dissolved gases, notably oxygen, nitrogen and carbon dioxide. Professor Pashley’s work suggests that these dissolved gases interfere with the water’s ability to be attracted electrostatically to the oil molecules.
Pashley began by degassing the water by repeatedly freezing and thawing it and drawing off the gases that were released. He has since developed a simpler process that uses semi-permeable membranes.
Degassing the oil as well greatly improves the results. Pashley found that simply mixing the oil and water and then degassing them led spontaneously to a cloudy emulsion.
This discovery could have important implications for agriculture and horticulture. Currently, hydrophobic chemicals and spray oils have to be mixed with a surfactant before they can be sprayed on crops. But surfactants can damage tissue surfaces. The development of a field technology to degas water could broaden the use of chemicals, particularly the non-toxic spray oils.
Even more importantly for human health, the direct mixing of drugs with water greatly expands the range of drugs that can be injected directly into the bloodstream.
Further reading
Pashley RM. 2003. Effect of degassing on the formation and stability of surfactant-free emulsions and fine Teflon dispersions. Journal of Physical Chemistry B 107: 1714-1720.