The Influence of Polymer Concentration on Performance and Morphology of Asymmetric Ultrafiltration Membrane for Lysozyme Separation

Investigation of UF membranes fouling and potentials as pre-treatment step in desalination and surface water applications

“…The increased surface area will give rise to more functional groups on the surface of these PES membranes, which will contribute to the total net charge. The ZP measurement patterns, as a function of pH, obtained in this work were contradictory with what was observed in previous research by Sofiah et al, who reported an increase in the ZP negativity of PES membrane by almost double as the polymer concentration increased in the dope casting solution from 13 wt% to 17 wt% [17]. alt-text: Fig.…”

“…1A shows a well-developed skin layer, connected and supported by a system of wide finger-like macro-pores, as can be observed at the bottom of the PES16 membrane. This structure is most apparent for membranes fabricated with a low viscosity casting solution, where the nonsolvent exchange rate into the polymer lean phase exceeds the outward solvent diffusion rate [17]. Increasing the polymer concentration suppressed these macro-pores in the sub-layer and led to a slightly narrower finger-like structure from the top to the bottom layer of the PES18 membrane, (Fig.…”

Formation of Low Acetyl Content Cellulose Acetate Membrane for CO2/N2 Separation

“…This is because the viscosity of the casting dope is higher than of M1, which increased the precipitation rate and caused a faster phase-separation at the skin-layer. 17 Figure 1(e and f) exhibits a smooth membrane surface on M3, with a skin-layer of 0.56 µm. It possesses the densest and thinnest skin-layer compared with M1 and M2.…”

“…This resulted in immediate phase separation at the skin-layer and slowed the precipitation rate which reduced the pore size in the membrane. 17 Besides that, the higher polymer concentration caused the polymer chains to entangle at the top skin-layer, thus reducing the formation of macrovoids and producing a thinner, smoother skin-layer. 17…”

“…As a result of the increment in the polymer concentration, the phase-separation at the skin-layer produced faster and a denser skin-layer formed. 17 This agglomeration of polymer at higher polymer concentrations of CA at 20 wt% (M3) might reduce the formation of a porous support structure that provides the membrane mechanical strength. Thus, M3 was also able to only build-up pressure to 2.0 bar.…”