This Small Business Innovation Research (SBIR) Phase II project will take advantage of the unique properties of carbon-nanotube (CNT) pores to develop membranes that are specifically tailored for forward osmosis (FO) applications. FO processes have a number of advantages over evaporation and pressure-driven membrane processes: low energy cost, low mechanical stresses, and high product concentration. The main problem impeding the widespread use of FO remains the lack of robust optimized FO membranes. CNT membranes are ideal for FO applications as they offer improvements in all relevant membrane characteristics: (1) improved structural integrity; (2) high permeability; (3) robust chemical stability; and (4) low fouling propensity. Most importantly, CNT membranes can be fabricated with sufficient structural support in the active layer to operate with only minimal external reinforcement, which minimizes concentration polarization losses. This project builds on the fabrication and functionalization approaches developed in Phase I, and applies them on a larger scale to achieve the objective of developing membranes with fast flow and high selectivity at reasonable production costs. Performance of the membranes will be benchmarked using laboratory tests that simulate real-world applications. This project will deliver an innovative FO membrane platform that exhibits superior performance and stability in FO applications.
The broader impact/commercial potential of this project will be to enable a variety of green technologies such as renewable power generation, wastewater reuse, and energy-efficient desalination. Although FO-based processes are extremely energy efficient, their commercial use has been hampered by the lack of high performance FO membranes. This project should produce two main outcomes. First, it would deliver a solid technical foundation for developing a novel FO membrane platform that would provide a superior commercial alternative to existing FO membrane architectures. Second, the performance advantages of the CNT membranes would open up several applications for commercial development.
In this project we conceived, developed, scaled up and commercialized a new forward osmosis membrane. This membrane is the critical component of a new line of products that Porifera started selling in 2014. Major activities involved laboratory work on membrane development, optimization of yields, performance and cost when produced on commercial-scale equipment, as well as a limited work on application development for this membrane. Our membrane development started with development of aligned carbon nanotube membrane composites. While we were able to achieve good performance with these membranes, they were difficult to make and expensive to manufacture. Serendipitous discovery associated with carbon nanotube work, led to the development of a novel polymeric forward osmosis membrane that was considerably cheaper and easier to manufacture. We proceeded with further optimization and characterization of this polymeric membrane. While we were initially able to develop a membrane with excellent performance, the materials used in it were relatively costly, constituting about 70-80% of the membrane cost. In this project we were able to demonstrate that we can achieve nearly the same performance using considerably cheaper materials. In addition we have developed short-term and long-term membrane storage procedures. Finally, we demonstrated excellent performance of our FO membrane in pressure retarded osmosis applications and as a key component of a hydration pouch. The applicable areas for introduction of our FO membrane fall into 4 market segments: Production of Water Filtration Kits for Emergency Hydration Wastewater Reclamation for Oil & Gas Shale Drilling Industrial and Municipal Wastewater Treatment Advanced FO applications, including Desalination, Algae-based Biofuel production, and Osmotic Power Generation
