The effect of deaeration on the surface tension of water and some other liquids

We studied the effect of the passage of nitrogen, helium, oxygen and/or atmospheric air through the liquids on the surface tension. The surface tension measurements were made in organic solvents as well as in aqueous surfactant solutions. The surfactants used, sodium dodecyl sulphate and hydroxypropylmethylcellulose were added in water after deaeration. The results showed that there was a small change in the surface tension of all solvents studied. The kinetics of adsorption of surfactants at the air/aqueous solution interface changed. Small differences were observed with the gases used. Additional pH and total organic carbon measurements were made, which excluded the effect of carbon dioxide to the observed surface tension changes. The results indicate that the changes in the surface tension are probably due to changes in the water “structure” and are permanent.