Impact of membrane characteristics and chemical ageing on algal protein fouling behaviour of ultrafiltration membranes

• Published in: Separation and purification technology Vol. 354; p. 128481
• Main Authors: Mustafa, Zainab Z., Murdock, Adrian T., Xie, Zongli, Johnston-Hall, Geoffrey, Henderson, Rita K., Leslie, Greg L., Le-Clech, Pierre
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Ageing; Chain scission; Fouling; Pore size; Surface roughness; Chain scission; Pore size; Surface roughness; Fouling; Ageing
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.128481

[Display omitted] •Chemical ageing decreased membrane hydrophilicity and pore size.•NaOCl exposure linked to additive loss and potential PVDF chain scission.•Long-term chemical ageing reduced membrane rejection of biopolymeric organics.•Smaller membrane pore size can provide higher long-term resistance to chemical degradation. Membrane characteristics can exacerbate the prevailing challenges associated with membrane fouling in industry. However, the combined impact of deliberate membrane modifications and the unavoidable effects of chemical ageing on fouling behaviour is still not well understood. In this study, three polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes with different pore size and surface roughness were selected and subject to chemical ageing with 5000 ppm sodium hypochlorite (NaOCl) at pH 10.5, selected to simulate accelerated ageing conditions. The impact of NaOCl on membrane characteristics was assessed for exposure times from 1.2 x 105 to 25.2 x 105 ppm·h using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, contact angle, and clean water resistance analysis. The fouling behaviour of each pristine and aged membrane was compared using 10 mg C·L−1 dissolved organic carbon algal protein feed containing 18 % biopolymeric compounds. The membrane with intermediate pore size presented lower overall filtration resistance compared to the membrane with smaller pores that developed rapid foulant cake layers. It also displayed less susceptibility to fouling via pore blocking mechanisms compared to membranes with larger pores where greater surface area available in pore walls leads to higher foulant adhesion.