Separation of emulsions using fibrous fabric

The separation of emulsions is a difficult problem which is frequently encountered in industry. Physical treatment processes involving the use of membranes are commonly used to separate one phase from another. The study to be described involves the determination of the efficiency of an emulsion separation process, using a fibrous membrane. An emulsion consisting of oil (di-n-butyl phthalate) droplets in water was made to flow, at various rates through a membrane comprising of a mat of aramid (du Pont, USA, Kevlar(TM) 49) fibre. An increase in the oil phase concentration of the emulsion, causes an increase in the separation efficiency and an optimum concentration that provides the maximum separation is identified. Increasing the flow fate and the fabric thickness, obtained by using multiple layers of fabric, were both found to lower the separation efficiency. It was observed that the Kevlar(TM) fabric had a natural saturation oil phase limit, which was reached more rapidly for the thicker fabrics. The critical oil exposure volume (COEV), (saturation volume) was calculated to be between 0.66-2.82 x 10(-3) m(3) of oil per m(2) of flux area of fabric per fabric layer for different fabric thickness. However, the values are not the absolute natural saturation limits. Calculations performed using the various separation rates, determined from the experimental results, for each fabric thickness suggest that distinctly separated single Kevlar(TM) fabric units have a significantly higher separating efficiency than multiple adjacently arranged Kevlar(TM) fabric units. (C) 2000 Elsevier Science B.V. All rights reserved.