This project involves an interdisciplinary university-industry partnership between UNC-Chapel Hill and Agile Sciences, Inc. with the objective of: (1) developing innovative reverse osmosis (RO)/nanofiltration (NF) membranes with enhanced anti-biofouling properties, and (b) building a fundamental understanding of how targeted incorporation of small molecules in the structure of RO/NF membranes affects their physico-chemical properties and performance. The anti-biofouling behavior of the proposed membranes is based on the incorporation of 2-aminoimidazole (2AI) into the structure of the polyamide active layer of RO/NF membranes. 2AI molecules are the only small non-toxic organic molecules that have been shown to inhibit biofilm formation for a wide range of bacteria, and to retain their anti-biofouling properties when attached to a surface. The 2AI molecules will be incorporated both throughout the entire membrane active layer (bulk incorporation) and only at the surface (surface incorporation). Once the 2AI molecules are incorporated into the polyamide active layer, the extent and location of incorporation will be varied systematically to build a fundamental understanding of how targeted incorporation of 2AI small molecules in active layers affects the active layer physico-chemical properties and membrane performance. Equipped with this understanding, the PIs will optimize membranes for anti-biofouling activity, fouling/scaling behavior, water flux and salt rejection. The optimization process will use a series of screening performance tests that will evaluate biofilm inhibition in static conditions, anti-biofouling activity under accelerated biofouling conditions during membrane filtration, conservation of anti-biofouling activity upon successive fouling-cleaning cycles, and organic and colloidal fouling and scaling behavior. The tests will use cross-flow membrane systems, bacterial solutions and natural waters provided by treatment plants. In this project the PIs plan to develop the first non-biocidal biofilm-inhibiting membranes that actively interfere with bacterial signaling mechanisms that trigger biofilm formation.
Broader impacts. The development of anti-biofouling water filtration membranes based on 2AI molecules will help establish this new chemistry as a viable approach to achieve anti-biofouling behavior. This development will benefit all fields where antibiofouling surfaces are important (e.g., medical implants, fuel cells, food processing, etc.). The fundamental understanding of the effects that membrane modification with small molecules has on membrane physico-chemical properties and performance will serve as valuable information for membrane developers to accelerate development and optimization cycles. The educational and outreach activities in collaboration with the Chapel Hill High School, Institute for the Environment (Chapel Hill, NC), and Elizabeth City State University (NC), a historically black university, will foster and broaden the participation of women and minority students in engineering and sciences and produce water-related educational materials for dissemination to the broader education community. The PI also plans to disseminate information regarding procedures based on time-of-flight secondary ion mass spectrometry (TOF-SIMS), Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) as useful methods in the study of the structure and properties of RO/NF membrane active layers.
