Froth Flotation and Bubble Foam Purification

Bubbles are formed in the sintered glass as air or other suitable gases (N2, C02, etc.) is bubbled through the solution containing the solid suspension. A suitable flotation agent (a suitable-surface active agent) is added, and the air is bubbled. 

Bubbles are blown into the inverted funnel. Inside the funnel, the bubble film is transported away and collected. Since the bubble film consists of a surface-active substance and water, it is seen that even very minute amounts (less than milligram per liter) of surface-active substances will accumulate at the bubble surface. As shown previously, it would require a large number of bubbles to remove a gram of substance. However, since one can blow thousands of bubbles in a very short time, the method is found to be very feasible. 

FIGURE 8.6 Bubble foam separation method for wastewater purification. 

In this chapter, special application of surface chemistry principles pertaining to the oil and water phases will be considered. Oil and water do not mix if shaken. As is well known, if one shakes oil and water, oil breaks up into small drops (of about a few millimeters in diameter), but these drops join together rather quickly to return to their original state (as shown here). 

Step I Oil phase and water phase Step II Mixing 

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