In this research, effect of bicomponent mixed surfactant was studied on DROP INTERFACE COALESCENCE phenomenon in ambient temperature. First basic chemical system was water and toluene and 0.01 gr of sodium dodecyle sulfate (SDS) and the second basic system was water and toluene and 0.01 gr of cethyl trimethy amonium bromide (CTAB). Various weight fractions of second surfactant including 2-heptanol (non-ionic) and aniline (cationic) added to each of these systems, respectively, in order to study the effect of mixed surfactant on COALESCENCE time. It was shown that chemical systems including mixture of nonionic/anionic surfactant increased COALESCENCE time. However, chemical systems including mixture of nonionic/cationic surfactant decreased COALESCENCE time. If a mixture of anionic/cationic surfactant was considered, in terms of being weak or powerful cationic surfactant, COALESCENCE time would have been decreased in the later and for mixture of ctionic/ctionic surfactant, COALESCENCE time increased in small diameter and decreased in further diameter. Effect of sodium chloride (NaCl) on selected systems, including 40% CTAB in the basic system of water and toluene and SDS, 40% 2-heptanol in basic system of water and toluene and CTAB and 40% 2-heptanol in basic system of water and toluene and SDS was considered and it was shown that in general, COALESCENCE time decreases

Effects of binary mixtures of ionic/nonionic (sodium dodecyl sulfate/2-heptanol or 1-decanol) and nonionic/nonionic surfactants (2-heptnol/1-decanol) on DROP/INTERFACE COALESCENCE of water DROPs in a continuous n-heptane phase were examined. The DROP size reduced appreciably and the multi-step COALESCENCE was suppressed finally as the concentration of each of the constituting components of surfactant mixture was increased. The DROP became more stable in comparison to single surfactant systems. It was concluded that the mixed surfactants were much more effective on COALESCENCE time and DROP lifetime than single surfactant, particularly when one of the components was soluble in the DROP phase.

In this research, the effect of mixed salts together with mixed ionic surfactants on DROPINTERFACE COALESCENCE time was studied for the system of water (d) / toluene(c) as a model system. Sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) as anionic and cationic surfactants were used. Sodium chloride (NaCl) and magnesium sulfate were used as salts. In the first stage of experiments, the system of water and toluene was influenced separately with SDS+NaCl, SDS+MgSO4, CTAB+NaCl and CTAB+MgSO4. It was observed that DROP size increased with SDS+NaCl and also with SDS+MgSO4. Partial COALESCENCE times increased for all systems. Overall, this increase of COALESCENCE time was more obvious when CTAB was applied. Also reduction in DROP size was observed. In the case of mixed surfactants with single salt, it was observed that partial COALESCENCE was suppressed for the system with (SDS+CTAB)+MgSO4. On the other hand, DROP size decreased and total COALESCENCE time increased. This may be due to the difference between the anions and cations of the two salts. For the case of mixed surfactants with mixed salts, DROP size and COALESCENCE time decreased.

In order to investigate the effects of DROP size and its falling distance on DROP INTERFACE COALESCENCE time, the so-called COALESCENCE cell had been designed and built. The selected chemical materials were as follows: Water-Toluene, Water normal Heptanes and 60% aqueous Glycerol-Toluene. In all experiments, the oil phase was as continuous phase. Before each run, the two immiscible phases were mutually saturated by mixing and then, separated from each other. It was indicated that, the increasing of DROP diameter or DROP falling distance increases DROP INTERFACE COALESCENCE time, separately. These factors also cause the subsidence of multistep COALESCENCE phenomena in water-Toluene system, which has usually occurred severely. Added to these, the vertical or horizontal fluctuations of DROP on INTERFACE, causes the delaytion of DROP COALESCENCE.

In this research work the effect of DROPlets size on DROP-DROP and DROP-INTERFACE COALESCENCE of sunflower oil in water emulsion in a non-uniform electric field has been in two systems “ DROP-DROP and DROP-INTERFACE COALESCENCE” under ramp-ac and square-ac waveform types investigated. In this work, the process was operated with the utilization of a batch cylindrical separator under high voltage condition. In this experimental work were of a constant frequency (60 Hz) and constant amplitude magnitudes 200 V/mm studied. Using a speed camera two patterns of COALESCENCE for both DROPs-DROPs and DROPs-INTERFACE was observed: complete COALESCENCE, incomplete COALESCENCE. The middle size of DROPlets was observed between 200 and 650 micrometers using “ Photron Fastcam viewer and image-pro software” .

In this research, the effect of simultaneous presence of single surfactant (ionic and nonionic) and salt on DROP-INTERFACE COALESCENCE was studied in the system of water (d)/ toluene (c).Sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) as anionic and cationic surfactants and also 1-decanol as nonionic surfactants were used. Sodium chloride (NaCl) and magnesium sulfate (MgSO4) were used as salts. It was found that mixture of surfactant and salt increased the COALESCENCE time. The effect of CTAB was more obvious in comparison with SDS. Also, MgSO4 caused much more increase in partial and total COALESCENCE time.

The three-dimensional oil-water flow in horizontal pipe has been investigated by introducing population balance equation (PBE). The water fraction of inlet flow and mixture velocity varies from 46% to 60% and from1. 25 m/s to 3m/s, respectively. The multiple size groups model has been applied to the non-uniform DROP size distribution in oil-water flow. The DROP COALESCENCE models have a clear efficacy on the prediction capability of the PBE. In this work, DROP COALESCENCE model for oil-water is modified and used for predicting the phase distribution of dispersed oil-water in horizontal pipe. Population balance with modified Coulaloglou’ s frequency model is used. The attention of the modification is on the presence of DROPlets that reduce the free space for DROPlet motion and cause an enhancement in the collision frequency. The phase distribution profile from numerical results is presented and discussed. Acceptable agreement with the experimental data is achieved by using the modified COALESCENCE model. Also, at 46% water fraction and mixture velocity equal as 3 m/s, model with population balance with modified Coulaloglou is 4% and 1% better than Luo’ s model and Coulaloglou’ s model, respectively.

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 the COALESCENCE 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.