The investigation of chemical cleaning of polymeric UF membranes: effect of temperature

This research investigated the impact of temperature on the chemical cleaning efficiency of the polymeric UF (Ultrafiltration) membranes. The retention of organic matter by UF membranes is one of the most widely discussed membrane applications, remaining relevant due to reversible and irreversible fouling. A higher degree of organic retention nurtures irreversible fouling, making standard chemical cleaning protocols less efficient. Typical solutions to increase cleaning efficiency raise operational expenses, but may not necessarily reduce the degree of irreversible fouling. This paper presents a microscopic investigation focused on short-term organic fouling and subsequent chemical cleaning. Polyethersulfone (PES) membranes were fouled with a synthetic mixture of proteins, fats, carbohydrates, and organic acids and then cleaned at temperatures ranging from 5 to 50 °C. The fouled membranes were separately cleaned using nitric acid, sodium hydroxide, and sodium hypochlorite. Water flux, contact angle, zeta potential, and microscopy analysis were utilized to investigate the membrane properties. The experimental results showed that the cleaning at low temperatures led to reduced fluxes. Sodium hypochlorite demonstrated the highest cleaning efficiency. The data obtained suggest that temperature could be considered as a cleaning approach, but optimal conditions should be carefully developed. Cleaning temperature is one of the crucial parameters impacting the chemical cleaning efficiency.