(16c) Demulsification of the Phosphoric Acid-Tributyl Phosphate (W/O) Emulsion By Hydrocyclone

Authors: 
Jin, Y., Sichuan University
Research Interests: separation by hydrocyclone,demulsification of water-in-oil emulsion, drop coalescence behavior, liquid-liquid dispersion

Teaching Interests: mechanical separation

Emulsions are often generated as unwanted byproducts during the mixing of organic and aqueous phases, but they are required in the emulsification extraction to greatly improve the extraction rate by increasing the contact interfacial area between the two phases. A rapid, convenient, efficient and economic demulsification method is subsequently needed to separate the two phases whether the emulsions are required or not. Liquidâ??liquid hydrocyclone is efficient for the two-phase separation of emulsion systems with the aid of strong centrifugal force created by the swirling flow. In this study, a demulsification process of phosphoric acidâ??tributyl phosphate (W/O) emulsion was investigated by hydrocyclone. The drop size distributions and average drop sizes of the emulsions pre and post demulsification were measured. The average drop size differences were used to evaluate the demulsification performance. The force condition and coalescence process of drops in the hydrocyclone were analyzed. The effects of density difference between the two phases, inlet flow rate and structural parameters (large cone part angle, small cone part angle, cylindrical part height, inlet and overflow pipe inner diameter) of the hydrocyclone on the demulsification performance were investigated. Larger density difference between the two phases led to better demulsification performance. The demulsification performance firstly became better and then got worse with the increase of inlet flow rate. The decrease in large and small cone part angle, as well as the increase in cylindrical part height, inlet and overflow pipe inner diameter of the hydrocyclone had positive effects on the demulsification performance. The influence degree of structural parameters for the demulsification performance decreased in the order: the cylindrical part height > the large cone part angle > the inlet inner diameter > the overflow pipe inner diameter > the small cone part angle. The optimum density difference, inlet flow rate and structural parameters were obtained. Under the optimum conditions, the average drop size of emulsion increased from 4.78 to 55.07 μm, and the difference was 50.29 μm. The average drop size differences were associated with these above-mentioned parameters through a dimensionless model. The comparison between the experimental and calculated data showed that this model was reliable to predict the average drop size difference in most demulsification conditions by hydrocyclone.