Controlling polysulfone (PSF) fiber diameter and membrane morphology for an enhanced ultrafiltration performance using heat treatment

• Main Authors: Monica Kwong, Amira Abdelrasoul, Huu Doan
• Format: Article
• Language: English
• Published: Elsevier 2019-09-01
• Series: Results in Materials
• Subjects: Morphology; Fiber diameter; Heating; Tension; Relaxation; Molecules
• Online Access: http://www.sciencedirect.com/science/article/pii/S2590048X19300214

Membrane morphology is a key parameter that affects membrane characterization and performance. The objective of the current study is to control the morphology of the Polysulfone Membranes (PSF) for further flux improvement using heat treatment. The study investigated relaxed heating and tension heating as to how both of these approaches influenced membrane porosity and membrane fiber diameter. Furthermore, the influence of changed morphology parameters on the membrane’s performance, membrane fouling, and increase in transmembrane pressure were examined. PSF flat sheet membrane was selected for this study. PSF membranes were treated with relaxed heating and tension heating, from 180 to 195 ​°C for the duration of 1–5 ​h. In addition, computational density functional theory (DFT) with Lee–Yang–Parr (B3LYP) was used to study the behavior of molecular fragments of the PSF at the treating temperatures. The experimental results showed that tension heating contributed to stretching and rearranging the membrane fibers along the direction of the external force under the effects of both heat and tension. This resulted in an improved structural density of the internal fibers and a decrease in the fiber diameter. The optimum treatment of tension heating was determined to be 1 ​h at 185 ​°C, and had the optimum membrane porosity for an enhanced membrane flux and lower fouling. The computational behavior of molecular fragments of PSF showed atom vibrations, increase in bond lengths and a rise in the kinetic energy at 185 ​°C.