Tight ultrafiltration: Layer deposition of Trimesoyl chloride/β-Cyclodextrin onto Polysulfone/Poly (styrene-co-maleic anhydride) membrane for water treatment

Abstract

Polysulfone–Styrene Maleic Anhydride (PSF/SMA) ultrafiltration (UF) membranes were prepared by the thermally induced phase separation (TIPS) method. The morphology of the UF membranes was fine tuned by varying the concentration of SMA. The surface of the membranes was then modified by dip-coating with β-cyclodextrin (β–CD) and Trimesoyl Chloride (TMC) to form tight UF membranes. The effects of β–CD on the separation performance, structure, and morphology of the flat sheet PSF/SMA membrane were examined. The tight UF membranes were characterized and then tested for the removal of Bovine Serum Albumin (BSA) and Congo red from water. The thickness was varied by increasing the concentration of β-CD. When increasing the concentration of β-CD from 2.0 % w/v to 8.0 % w/v, the thickness of the top layer increased from 8 μm to 18 μm, respectively. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-Ray Photoelectron Spectroscopy (XPS) were used to confirm the successful deposition of the TMC and β-CD at the surface of the membrane. It was also established through Atomic Force Microscopy (AFM) that the roughness of membranes increases with an increase in β-CD concentration. The contact angle of the tight UF PSF/SMA blend membranes declined from 79.8° to 55.9° at the addition of β-CD implying that the hydrophilicity of the membranes improved. The lowest pure water flux of 40 Lm−2 h-1 was achieved by the membrane coated with 8.0 % w/v of β-CD. However, the highest pure water flux of 127 Lm−2hr−1 was observed on the uncoated PSF/SMA UF membrane at 3 % wt/wt SMA. The highest BSA rejection (94 %) was recorded from PSF/SMA with a coating layer containing 8 % wt/v of β-CD concentration. Furthermore, the maximum Congo red dye rejection (96 %) was achieved by the tight UF membrane when β-CD concentration was 8 wt/v and the SMA was 3 % wt/wt.