Prediction of effective diffusivity and using of it in designing pulsed sieve plate extraction columns

Pulsed columns are one of the most important liquid–liquid extraction equipments which have an extensive application in different industries. Determination of the mass transfer coefficients as one of the fundamental parameters is of great importance in pulsed columns design. In this paper, previous works which have been done on this subject is reviewed and a set of previous models presented in the past literature are examined. Comparison between these models and the experimental results shows that although some of these equations may have satisfactory results, they do not have enough accuracy for design. This research is based on the substitution of effective diffusivity for molecular diffusivity and attempt to access it experimentally. Using effective diffusivity in equations which have been derived from solving of continuity equation in spherical coordinates will result in more accurate prediction of mass transfer coefficients. Experimental results will lead to prediction of effective diffusivity as a function of Reynolds number. Making use of the presented model in prediction of mass transfer coefficients and calculation of column's height is in great compatibility with experimental results and is suggested for better design.