Influence of polymer concentration in casting solution and solvent-solute-membrane interactions on performance of polyphenylsulfone (PPSU) nanofiltration membrane in alcohol solvents

Abstract

In this work, the performances of solvent resistant nanofiltration (SRNF) membranes made of polyphenylsulfone (PPSU) were evaluated with respect to alcohol solvent (methanol, ethanol and isopropanol) flux and dye rejection. The experimental results showed that the solvent flux decreased while dye rejection increased with increasing polymer concentration in the casting solution from 17 wt% to 25 wt%. Apart from molecular size of the solute and viscosity of the solvent, the affinity between the solvent and the membrane was also confirmed to play a significant role in affecting the transport rate of the solvent through the membrane. With respect to the effect of solvent properties and solute size on the dye rejection of solvent-dye mixtures, it was found that the variation of dye rejection is governed by solvent-solute-membrane interactions. The solvent-solute interaction causes the same solute to have different solute size in each tested solvents, whereas the solvent-membrane interaction would result in a change in membrane pore size, leading to different separation efficiency. However, it must pointed out that solvent-membrane interaction is more pronounced compared to solvent-solute interaction, as the dye rejection of ethanol solution is reportedly higher than that of methanol, even though the size of solute in ethanol is smaller compared to its size in methanol.

Polyphenylsulfone-based solvent resistant nanofiltration (SRNF) membrane incorporated with copper-1,3,5-benzenetricarboxylate (Cu-BTC) nanoparticles for methanol separation

“…The greater uxes of the PPSU/Cu-BTC membranes in comparison to the PPSU membrane can be attributed to the pores of Cu-BTC which act as solvent preferential path, facilitating the transport of the methanol through the membrane. 9,45,46 With respect to MWCO, it is reported that the membranes incorporated with 0.5-1 wt% Cu-BTC display MWCO relatively smaller than that of control membrane while highest Cu-BTC loading (i.e. 7(e) might also create voids that lead to greater solvent ux.…”

Preparation and characterization of modified polyphenylsulfone membranes with hydrophilic property for filtration of aqueous media

“…Despite the aforementioned significant properties of PPSU, there have been a few numbers of studies concerning the preparation and characterization of flat‐sheet PPSU membranes for liquid filtration. The publications on liquid filtration using this kind of membrane generally focused on pervaporation, nanofiltration of solvents, ultrafiltration (UF), and adsorption‐enhanced UF …”

“…According to the literature, although Jansen et al have reported the preparation of PPSU/polyimide (PI) membrane for solvent‐resistant nanofiltration, the excellent solvent resistance of PPSU has led to appropriate performance of pure PPSU membranes in several solvent‐resistant nanofiltration studies . However, the 2 major drawbacks of this polymer, including its low water permeability and high fouling tendency, have limited its application in filtration of aqueous media. Therefore, membrane modification is required to address the aforementioned problems.…”

“…Therefore, membrane modification is required to address the aforementioned problems. Sani et al reported a much lower filtration flux for water (1.12 L/m 2 h) through the PPSU membrane in comparison with alcohols such as methanol (40 L/m 2 h), ethanol (15.07 L/m 2 h), and isopropanol (10.14 L/m 2 h). The reason for the above observation was explained by the remarkable difference in the polarity of PPSU and water as well as the difference in their surface tension.…”

“…Therefore, membrane modification is required to address the aforementioned problems. Sani et al 15 10,20 In addition to the low permeate flux resulted from the membrane hydrophobocity, 10 this characteristic contributes to the increased membrane fouling. 20 A high rate of membrane fouling increases the membrane replacement frequency, suggesting increased operational costs.…”