Modeling of permeate flux decline during ultrafiltration of polyvinyl alcohol in a batch cell

Ultrafiltration (UF) of polyvinyl alcohol from aqueous solution is studied in a batch cell over a wide range of operating conditions. The unsteady state nature of the permeate flux decline during UF is caused by changes in the hydraulic boundary condition at the membrane surface due to gel layer formation. An unsteady state mass transfer model is developed for gel-controlled UF in an unstirred cell starting from the basic fluid mechanical analysis of the system. An integral method of solution is used for the solution of the concentration profile in the developing mass transfer boundary layer. The model is used to predict the transient permeate flux decline profile. The transient state behavior in the presence of stirring is estimated by using a model available in literature. The predictions are found to be in good agreement with the experimental flux.