Nanofiltration Membranes

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Reference #: 01160 The University of South Carolina is offering licensing opportunities for a method of preparing ceramic nanofiltration membranes using molecular layer deposition. Invention Description: The subject invention is a novel use of molecular layer deposition (MLD) to fabricate ceramic nanofiltration membranes, which offers excellent control of coating quality, thickness, and membrane pore sizes by utilizing self-limiting surface reactions at the sub-nanometer level. The resulting membrane’s pores are approximately 1 nm in size. Currently, ceramic nanofiltration membranes are usually prepared by solution-based sol-gel method, which requires careful control of the deposition process to produce high quality membranes. Typically, in this process, a colloidal or polymeric solution is converted into a gel, and organic additives need to be added to control the hydrolysis and condensation of alkoxides. In addition, pore sizes of ceramic nanofiltration membranes are difficult to be precisely controlled at about 1 nm, especially for stable metal oxides, and membrane thickness may not be able to be controlled at the sub-nanometer scale. Advantages and Benefits: Compared to the traditional sol-gel method of fabricating ceramic materials, MLD is a gas phase deposition process that allows excellent control of membrane composition, thickness, and pore size by utilizing self-limiting surface reactions. This process also scales easily for deposition of large membranes areas. Potential Applications: Production of commercial-scale membranes for a wide range of water purification applications Background: Nanofiltration membranes are now widely used in purifying drinking water, treating wastewater, and pretreating for desalination because of their ability to remove viruses, hardness, dissolved organic matter, and salts. Generally, polymers are the dominant materials in nanofiltration membranes. While most polymeric membranes offer flexibility, simple preparation, and low costs, compared with polymeric nanofiltration membranes, ceramic nanofiltration membranes have better chemical, thermal, and mechanical stability, and long lifetime, and thus may be used in applications under extreme operating conditions. Development: MLD was used to prepare ceramic nanofiltration membranes with approximately 1 nm-sized pores. In one an example, the membranes exhibited a high pure water flux of 48 L/(m2·h·bar). They also showed high rejection for methylene blue (approx. 96%), humic acid (approx. 99%), and carbon sulfate (approx. 65%). Salt rejection measurements showed moderate rejection of sodium chloride (approx. 28%) and sodium sulfate (approx. 32%). The membrane was stable under pressure as high as 10 bar and operation time longer than 100 hours.