(646a) Surface Modification of Membranes to Improve Fouling Resistance

Across many platforms of membranes, fouling mitigation is a major challenge to be addressed to achieve the most energy-efficient, cost-effective membrane filtration processes.  Previously, many surface modifications and functionalized polymers were reported to prevent fouling.  However, most of these techniques and materials are practically difficult to implement in water purification membranes.  We have discovered surface treatment methodologies that can be used to prepare high permeability polymeric membranes from all common water purification membrane classes.¹  These surface-modified membranes have persistent tolerance to fouling by proteins and emulsified oil, two ubiquitous contaminants in a variety of wastewaters. These membranes were prepared by depositing bio-inspired, self-polymerized hydrophilic polydopamine nanolayers on their surfaces. To demonstrate scalability of this modification, the nanolayers were also applied to entire membrane modules. Upon nanolayer deposition, the membranes could be further functionalized using fouling-resistant macromolecules, such as poly(ethylene glycol), to promote improved fouling resistance and, therefore, high membrane flux.  More recent studies have focused on further characterizing the chemistry of formation of polydopamine,² exploring alterative molecules, such as hydroquinone and catechol,³ which exhibit similar effects to dopamine when deposited on membrane surfaces, and characterizing the ability of these surface modifications to improve performance of forward osmosis membranes.⁴

¹ McCloskey, B.D., H.B. Park, H. Ju, B.W. Rowe, D.J. Miller, B.J. Chun, K. Kin, and B.D. Freeman, “Influence of Polydopamine Deposition Conditions on Pure Water Flux and Foulant Adhesion Resistance of Reverse Osmosis, Ultrafiltration, and Microfiltration Membranes,” Polymer, 51, 3472-3485 (2010).

² Dreyer, D.R., D.J. Miller, B.D. Freeman, D.R. Paul, and C.W. Bielawski, “Elucidating the Structure of Polydopamine,” Langmuir, submitted.

³B.D. Freeman, D.J. Miller, and B.D. McCloskey, “Polymer Deposition and Modification of Membranes for Fouling Resistance,” U.S. Patent Application Number US 2010/0059433 A1, March 11, 2010.

⁴ Arena, J.T., B. McCloskey, B.D. Freeman, and J.R. McCutcheon, “Surface Modification of Thin Film Composite Membrane Support Layers with Polydopamine:  Enabling Use of Reverse Osmosis Membranes in Pressure Retarded Osmosis,” Journal of Membrane Science, 375, 55-62 (2011).