Spreading kinetics for low viscosity n-alkanes on a water surface as recorded by the high-speed video system

The spreading of small hydrocarbon droplets (pentane, heptane, dodecane, hexadecane) on the water surface was recorded using a Kodak high-speed video system with a speed of 1000 frames per second. The results showed that the spreading of low-viscosity hydrocarbons on a water surface is a very spontaneous process and is usually completed in 10-15 ms for drops with a diameter of 3-4 mm. It was found from the recorded images that the kinetics of a hydrocarbon droplet spreading on the deionized water surface follow a time n-power law: D~t, where D is the lens diameter, t is the time, and n=0.4-0.5. The kinetics of spreading for hexadecane droplets were slowed down and the n value was reduced to n=0.36-0.39 when deionized water was replaced by sodium dodecyl sulfate solutions. These results suggest that the kinetics of hydrocarbon spreading can be controlled through molecular arrangements at the waterfluid interfaces.