Phase inversion phenomenon occurs in many industrial processes including liquid - iquid dispersions. Some parameters such as energy input or the presence of mineral compounds in the system affect this phenomenon.The aim of this research is to study the speed of rotation or energy input at a range of 400 to 800 rpm in a batch liquid-liquid system containing toluene and water. The presence of sodium chloride and magnesium sulphate in the system was also studied.It was shown that the increase of energy input had a more obvious effect on oil in water (O/W) dispersion at lower values of holdup. It was also shown that the ambivalence (o/w ® w/o) region of the phase inversion curve shifted downward and became wider as a result of the decrease in interfacial tension.It was observed that inorganic salt, used in both single and dual (mixed) shapes, enhanced phase inversion for O/W dispersion. Therefore, the greater the ionic strength of salt, the greater the tendency to phase inversion is.

Phase inversion in liquid-liquid dispersions is a common phenomenon that occurs in many industrial processes. However, the mechanisms responsible for phase inversion and the effect of the physical and geometrical parameters on this phenomenon are not well understood. In this paper, the effect of agitation speed, type of chemical system and mineral salts on phase inversion behavior in batch-agitated vessels has been investigated. In order to study the phase inversion, a variable speed agitator and conductometer has been used. The results showed that with increasing agitation speed, the O/W dispersion invert at decreasing values of critical dispersed phase holdup, whereas W/O dispersions follow the reverse trend. Also, it is shown that decreasing interfacial tension of dispersion, shifts ambivalence limits downward and widening it. Also, addition of salt to water phase influenced phase inversion behaviour and facilitated the phase inversion of O/W dispersions and since the salt has higher ionic strength, its effect was higher.

Phase diagrams for the ternary (neopentyl glycol + sodium formate + water) system were measured. Phase equilibrium data were obtained at different temperatures of 333. 15, 343. 15, and 353. 15 K. The effect of temperature on the liquid–liquid phase equilibrium was studied and the length and slope of the tie-line at different temperatures for the conjugate phase were investigated. It was found that the tie-line length decreases and the two-phase area is slightly reduced by increasing temperature. The three fitting parameters of the Merchuk and Pirdashti equations were obtained with the temperature dependence expressed in the linear form, respectively. Compared with the Pirdashti equation, the binodal curves were described satisfactorily with the Merchuk equation, further, the plait points at various temperatures were estimated by extrapolation. The Othmer-Tobias and Hand models were used for the correlation of the phase equilibrium behavior. The correlation coefficients of the models were obtained for the corresponding temperatures. The results showed that it was well fitted with the Othmer-Tobias model by contrast with the Hand model

In the past decade, liquid-phase microextraction (LPME), which can also be called solvent microextraction, has emerged as a minimal organic solvent-based sample preparation approach. The main advantages of this method include versatility, simplicity and effectiveness of its extraction procedures at reducing sample complexity, as well as the convenience of liquid sample concentration and injection techniques. LPME is based on the distribution of analytes between the organic solvent and the aqueous solution. Hitherto, several different LPME modes have been developed. Some of the described methodologies usually offer slow extraction kinetics due to the low contact surface between the sample and the extractant phase. Since the introduction of dispersive liquid–liquid microextraction, a number of studies have been focused on the features of emulsification in preconcentration techniques. Emulsification enhances the surface area between the extraction solvent and aqueous sample by the efficient dispersion (chemically assisted or by the use of an external energy source) of the extractant in the sample. In this paper we review the emulsification-based liquid-phase sample preparation techniques. A brief practical and theoretical description of each technique and some applications are given.