Superhydrophilic Thin-Film Composite Forward Osmosis Membranes for Organic Fouling Control: Fouling Behavior and Antifouling Mechanisms

• Published in: Environmental science & technology Vol. 46; no. 20; pp. 11135 - 11144
• Main Authors: Tiraferri, Alberto, Kang, Yan, Giannelis, Emmanuel P, Elimelech, Menachem
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16-10-2012
• Subjects: Alginates - chemistry; Applied sciences; Biofouling - prevention & control; Chemical engineering; Drinking water and swimming-pool water. Desalination; Effluents; Exact sciences and technology; General purification processes; Glucuronic Acid - chemistry; Hexuronic Acids - chemistry; Hydrophobic and Hydrophilic Interactions; Membrane separation (reverse osmosis, dialysis...); Membranes; Membranes, Artificial; Nanoparticles; Nylons - chemistry; Osmosis; Pollution; Simulation; Solution chemistry; Thin films; Waste Disposal, Fluid - methods; Waste Water - chemistry; Waste Water - microbiology; Wastewaters; Water Purification - methods; Water treatment and pollution; Membrane separation; Water treatment; Fouling; Functionalization; Nanoparticle; Physicochemical purification; Osmosis; Waste water purification; Nanostructured materials; Composite material; Thin film; Hydrophily
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es3028617

This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes.