Department of Chemical Engineering, Faculty of Engineering, Tehran University, P.O.Box. 11365-4563, Tehran, I.R. IRAN
After designing and constructing a coalescence cell, drop/interface coalescence phenomenon was studied in the absence and presence of single surfactant.Two surface active agents of sodium dodecyl sulfate and 1-decanol were used. Distilled water was used as dispersed phase. Toluene, n-heptane and aqueous 60% (v/v) of glycerol were selected as continuous phases, separately. It was found that thecoalescence time increased with both drop size and falling height. When the chemical system suffered from multi-step (partial) coalescence, number of coalescence steps decreased with either of these variables. Addition of a single ionic or nonionic surfactant made the drop size smaller, and hence caused the onset of partial coalescence. When the surfactant was soluble in the drop phase, it increased the time more effectively. Also, It was found that the viscosity of the continuous phase played an important role in drop-interface coalescence. Based on the experimental results, new correlations were proposed. Then, the results were compared with the other models by application of the existing condition.
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