Identification of optimal membrane morphological parameters during microfiltration of mosambi juice using low cost ceramic membranes

Abstract

In this work, experimental investigations were carried out for the identification of optimal membrane morphological parameters (pore size distribution, average pore size and porosity) during microfiltration (MF) of mosambi juice using low cost ceramic membranes. Four different low cost ceramic membranes with different pore diameters ( d m) and porosities ( ɛ) were subjected to MF studies to evaluate the effect of d m and ɛ on permeation characteristics (permeate flux and juice quality) of centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). Subsequently, a convenient factor namely effective permeable area factor ( ɛ m d m 2) was evaluated to provide greater insights in the fouling phenomena. Various physio-chemical properties such as colour, clarity, pH, citric acid content, density, total soluble solid (TSS) and alcohol insoluble solids (AIS) were measured for both feed and permeate juice samples to evaluate the effect of ɛ m d m 2 on juice quality. Typical permeate fluxes were observed to vary from 5.78 × 10 −6 to 13.45 × 10 −6 m 3/m 2 s for CJ and 14.07 × 10 −6 to 60.64 × 10 −6 m 3/m 2 s for ETCJ at 82.7 kPa (Δ P) for different membranes whose ɛ m d m 2 varied from 0.249 to 0.783 μm 2. Among different membrane pore blocking models, flux decline by cake filtration was found to be the best fitted model. The cake filtration model constant ( k c) was found to vary with Δ P and ɛ m d m 2 and was empirically correlated. Phenomenological models were proposed to illustrate the dependency of total hydraulic resistance of membrane on ɛ m d m 2, Δ P and time ( t). Based on experimental as well as theoretical investigations, membranes with ɛ m d m 2 up to 0.443 μm 2 for CJ and 0.294 μm 2 for ETCJ and a Δ P of 82.7 kPa were recommended for MF of mosambi juice.