Innovative Filters Using Nanomaterials for Removal of Gaseous Pollutants and Particulates from Contaminated Air Streams

A uniquely qualified team consisting of ETSVP-JV, a small business joint venture, and subcontractor RTI International, brings together all of the skills and experience needed for the development and testing of innovative nanomaterial filters. For this Phase I SBIR project, we propose to develop a dual-stage nanoporous filter media for controlling PM2.5 and volatile organic compounds (VOCs). Materials developed for the Department of Defense to protect troops from chemical and biological agents are the foundation for next-generation filter media for pollution control of Hazardous Air Pollutants (HAPs). We will develop filter media that will significantly enhance combined PM and HAP baghouse control capabilities over current state-of-the-art products. We propose the application of two novel technologies: a method for making nanofiber mem branes and a method of encapsulating the nanofiber membrane with a conformal nanoscalc coating. The filtration membrane is formed from a nonwoven mat of nanofibers. Fiber size and distribution are controlled to below 200 nm. The technique developed to deposit the nanofibers on a support controls the fiber orientation and three dimensional packing of the fibers. The process produces a cleanable membrane with significantly better particle filtration collection efficiency as a function of pressure drop when compared to other filtration materials. The method of encapsulating the nanofiber membranes is based on a vapor phase deposition process called atomic layer deposition (ALD). ALD provides for highly conformal coatings with controllable nanometer thickness and a wide range of chemistries, including some with catalytic properties. One application will be to coat the fibers in the nanofiber membrane for resistance to aggressive high temperature stack conditions. The second application of ALD will be to coat both passivated nanofibers and conventional baghouse felt media fibers with reactive or catalytic coatings. These reactive flexible coatings of catalytic materials for the oxidation of VOCs will retain the particle filtration capabilities while taking advantage of the high surface area of the media.These new baghouse media will be tested in accordance to ASTM and EPA test methods. Their performance will be compared to conventional media for performance and durability. Our goal is to develop a new flexible filter media for control of a wider range of HAPs and more efficient fine particulate control. The proposed nanomaterial filter meets the EPA’s challenge of tighter particulate and VOC emission limits.