Novel grafting method efficiently decreases irreversible fouling of ceramic nanofiltration membranes

Availability of clean water is a growing world-wide challenge. Membrane filtration is considered to be a very powerful technology to tackle this problem. While membranes have enjoyed increasing popularity, the technology has an inherent Achilles heel: fouling. Despite being frequently studied, fouling remains poorly understood and incompletely resolved. The most sustainable way to mitigate fouling is the prevention of the undesired adsorption by nano-engineering of the membrane surface. In this study, commercially available TiO2 NF membranes were modified applying both Phosphonic acids and Grignard grafting techniques. Hydrophilicity, pore size, and structural changes after grafting were investigated by measuring water contact angles, molecular weight cut-off values, and water permeabilities. Model foulants mimicking fouling in surface water treatment for drinking water production, one of the difficult fouling situations, were used. From the obtained results, it was concluded that grafting of NF TiO2 membranes by the mentioned techniques definitely decreases their fouling tendency. Correlation of foulant and membrane surface chemistries for a variety of foulants and graftings provided understanding of the fouling process at nanoscale, and underlined the importance of the unique bond created by Grignard grafting. These ground-breaking insights allowed us to steer further anti-fouling strategies, and are valuable to other affinity-based separation processes.