into the beakers, a piece of acryl plate(15cm x 2cm) was partially put in the oily water of each beaker and was kept for one second. The appearance of the adhering of oil droplets on the plates was photographed with a 35m/m camera and a microscopic camera.
The photographs are shown in Photo.2 (the case of a settling time of 5 minutes) and Photo.3 (the case of a settling time of 20 minutes).
The upper photos of both Photo.2 and Phot0.3 were taken with the microscopic camera. The lower photos were taken with the 35m/m camera.
The range of droplet size in Photo2 is 2.01~46.3lx m and that in Phot03 is 2.01~28.2,1 m. As observed in the photos, while larger oil droplets adhered to a piece of acryl plate (Photo.2), smaller droplets can be observed only in the upper photo taken with the microscopic camera of Photo3.
The result revealed that larger droplets have a marked tendency to adhere to some substrata, while droplets less than 30f/ m have a faint tendency to adhere.
Photo.2 Adherence d the droplets b a solid object after a settling time d 5min
Photo.3 Adherence of the droplets to a solid object after a settling time d 20 min.
5 Conclusion
This report is a part of the three-year reseach project which was started in 1994 and continues to do,
The conclusion of this report is as follows:
・Conventional dispersants turn out to be ineffective with oil of viscosity of more than 3,000cSt. Dispersion rate of the dispersant does not meet the threshold of Japanese test standard.
・Combinations of some surfactants with some solvents were found likely to be amenable to high-viscosity oils.
・Larger droplets of dispersed oil not only resurface faster in the ~ water, but a[so coalesce more, consequently, less effective the dispersant becomes.
・Where droplet sizes of dispersed oil are less than 30μ min diam., the droplets do not have a tendency to adhere other objects such as a piece of acryl plate.
・Droplet sizes of oil in the consistent (stable) oil-in-water emulsion a less than 30,x m, have a weak tendency to cohere to each other or to coalesce.
