Performance Of Nanofiltration Process Research Articles

Performance of nanofiltration process during concentration of strawberry juice.

The aim of this study was to evaluate the microfiltration and nanofiltration of strawberry juice. Processes performance was evaluated in terms of resistances-in-series, flux decline modeling and extract quality (maintenance of the phenolic compounds). The results obtained showed that concentration polarization is the main resistance to permeate flux in nanofiltration process, representing around 95% of the total resistance. Microfiltration process suffered more influence of the concentration polarization and fouling, next to 47% for both resistances. For all the processes, Hermia's pore blocking models presented good fitting, with R2 over 0.85. The same behavior was observed for a conjugated model which provided a realistic description (R2 > 0.76). Also, nanofiltration process allowed phenolic compounds maintenance, demonstrating the efficiency of this process for strawberry juice concentration.

Analysis of flux decline using sequential fouling mechanisms during concentration of Syzygium cumini (L.) leaf extract

Experimental studies were performed in a stirred cell for concentration of MF-pretreated extracts from jamun (Syzygium cumini L.) leaves using nanofiltration over a wide range of operating conditions. Performance of nanofiltration process was evaluated in terms of permeate flux, flux decline and extract quality (total polyphenol content, total flavonoid content and antioxidant activity). A total of ten phenolic compounds including six phenolic acids and four flavonoids were identified and quantified in jamun leaf extract using HPLC. A combined sequential model consisting of Hermia’s complete pore blocking and cake layer formation based on resistance-in-series theory was considered to explain the flux decline behavior with time. The model calculations were shown to be in excellent agreement with experimental flux data (R2>0.90; SD<2.5%). Experimental results showed that the operating conditions had significant effect on the onset of cake layer formation. The pore blocking resistance was found to be comparable with membrane resistance, while cake layer resistance was 20–40% of membrane resistance. In addition, the permeate flux for MF-pretreated extract was always higher than that for the untreated extract. The present study with the estimated model parameters provided important understandings into the underlying mechanisms of membrane fouling phenomena during concentration of jamun leaf extract.

Specific model for nanofiltration

A model is developed which describes mass transfer through the combination of convective–diffusive flux in the pores and a diffusive flux in the membrane material. This model takes into account membrane (membrane permeability, pore size) and solution (charge and size of the molecule) characteristics via five parameters which can be estimated from experimental data. This model is first validated by comparison with experimental results and then used as a tool to evaluate the influence of the membrane solution characteristics on the performance of nanofiltration process.