Organic fouling inhibition on electrically conducting carbon nanotube–polyvinyl alcohol composite ultrafiltration membranes

• Published in: Journal of membrane science Vol. 468; pp. 1 - 10
• Main Authors: Dudchenko, Alexander V., Rolf, Julianne, Russell, Kyle, Duan, Wenyan, Jassby, David
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2014; Elsevier
• Subjects: Alcohols; Chemistry; Colloidal state and disperse state; Crosslinking; Electrically conductive membranes; Electrostatic forces; Exact sciences and technology; Fouling; General and physical chemistry; Inhibition; Mathematical analysis; Membranes; Modified Poisson–Boltzmann; Nanostructure; Organic fouling; Ultrafiltration; Waste water; Electrostatic forces; Ultrafiltration; Electrically conductive membranes; Modified Poisson–Boltzmann; Organic fouling; Fouling; Carbon nanotubes; Modified Poisson-Boltzmann; Composite material; Membrane separation; Polyvinylalcohol; Membrane; Inhibition; Electrostatic force
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2014.05.041

Robust and electrically conductive thin films (2500S/m) made of cross-linked poly(vinyl alcohol) and carboxylated multi-walled carbon nanotubes (PVA–CNT–COOH) were synthesized via a sequential deposition and cross-linking method. The PVA–CNT–COOH modified membranes were then used in an electrofiltration cell in which the effects of applied potentials on fouling of high concentrations (3–5g/L) of alginic acid (AA) were studied. It was demonstrated that after 100min of operation while applying −3V and −5V, the change in operating pressure was reduced by 33% and 51%, respectively, compared to application of no voltage. Increase in ionic strength resulted in overall higher fouling rates, where the application of −5V resulted in a pressure change reduction of 43% compared to no application of potential. A modified Poisson–Boltzmann equation used in a DLVO-type theory demonstrated that at the applied potentials, electrostatic interactions produced significant repulsive forces between the membrane surface and the charged organic foulant. Calculations at experimental conditions demonstrated the pure AA aggregates would be strongly repulsed away from membrane surface. In synthetic wastewater the repulsion force is greatly reduced, resulting in overall reduced fouling inhibition. •Highly conductive PVA–CNT thin films were deposited onto ultrafiltration membranes.•PVA–CNT thin films exhibited high hydrophilicity, robustness, and smoothness.•Application of high potentials to thin films reduced fouling by up to 51%.•Modeling demonstrated the impact of strong electrostatic forces.•Electrostatic forces were concluded to be primary antifouling force.