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

EPA Contract Number: EPD14022
Title: Innovative Filters Using Nanomaterials for Removal of Gaseous Pollutants and Particulates from Contaminated Air Streams
Investigators: McKenna, John D
Small Business: ETSVP-JV, LLC
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: May 1, 2014 through April 30, 2015
Project Amount: $99,902
RFA: Small Business Innovation Research (SBIR) - Phase I (2014) RFA Text |  Recipients Lists
Research Category: Nanotechnology , SBIR - Air Pollution Monitoring and Control , Small Business Innovation Research (SBIR)

Description:

A uniquely qualified team consisting of ETSVP-JV, LLC; a small business joint venture; and subcontractor RTI International brought together all of the skills and experience needed for the development and testing of innovative reactive nanofiber filtration media for controlling fine particles (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). For this Phase I project effort, the team developed a novel dual stage reactive nanofiber filtration media that significantly enhances combined particulate matter (PM) and HAP baghouse control capabilities over current state-of-the-art filtration.

The reactive nanofiber filtration media is composed of two components: a nanofiber membrane and a reactive nanoscale coating. For the Phase I project, the team focused on the methods for forming and combining the two components of the reactive nanofiber membrane into a single filtration system. The nanofiber membrane consists of fibers with a fiber size and distribution controlled to below 200 nm. The membrane is supported by a nonwoven backing mat to support the nanoscale architecture of the nanofiber membrane. The technique developed to deposit the nanofibers on the nonwoven support arranges the fiber orientation into a unique three-dimensional structure of fibers that controls the pore size and slip flow velocity through the media. The unique nanofiber structure improves the interception and collection of particles, such as fine particulates like PM2.5, because the particle size is much larger than the fibers in the media. The nanofiber membrane, when compared to other filtration materials, has significantly better particle filtration collection efficiency as a function of pressure drop. The second component of the reactive nanofiber membrane consists of a method to encapsulate the nanofiber membranes with highly conformal nanoscale coatings that are typically less than 25 nm. The nanoscale coatings can be deposited from a wide range of chemistries including some with catalytic properties. The commercial target for the reactive nanofiber membrane is aimed at pollution control and reduction of emissions from sources such as coal fired power plants. The membrane offers two routes for commercialization and improving air quality. The first approach is targeted at collection of fine particulate matter from hazardous air streams by protecting the nanofiber membrane with a thin nanoscale coating that encapsulates the fiber media with a hard shell and protects it in aggressive high-temperature stack conditions. The second approach is targeted at reducing HAPs, such as VOCs, by applying reactive or catalytic nanoscale coatings on the nanofiber membrane. The reactive coatings take advantage of the high surface area of the nanofiber media by increasing the available surface area for reaction and oxidation without sacrificing any of the high particle filtration capabilities.

Summary/Accomplishments (Outputs/Outcomes):

In the first case, fine particulate emission control was demonstrated at a level below the project goal of 0.00004 grains per dry standard cubic foot (gr/dscf). Using the ASTM D6830-02 test method and the EPA/ETV protocol, the testing showed a PM2.5 mean outlet concentration of 0.0000261 gr/dscf. Average permeability of 7.9 feet per minute (fpm) was measured along with average Mullen burst strength of 633 psi. Average MIT flex endurance values of 259,917 flexes in the warp direction and 100,709 flexes in the fill direction were registered.

 

In two separate tests, VOC removal was conducted at ambient temperature and again at 100°C with no VOC removal. The plan was to run at 150°C, a temperature where the catalyst is known to perform; however, Phase I funding and time were exhausted. This would be an early testing priority in the Phase II contract.

Conclusions:

As particulate emission regulations have become more stringent, the use of baghouses rather than electrostatic precipitators (ESPs) for fly ash control has become prevalent. The application of the baghouse for control of fly ash emissions from utility and industrial coal fired boilers (CFBs) predominantly employs PPS felt bags with pulse jet cleaning. As the emission codes have tightened, the use of an expanded polytetrafluoroethylene (ePTFE) membrane on the filtration media has been added so as to achieve compliance. Given the PM2.5 filtration performance demonstrated, the use of composite nanofiber filtration media for particulate emission control is technically competitive with ePTFE membranes. An Electric Power Research Institute (EPRI) survey indicated that there were 142 pulse jet baghouses installed by 2012 in U.S. power plants. The typical pulse jet bag life is approximately 4 to 6 years, thus the bag replacement market opportunity for an alternative bag type is significant. Likewise, further study should allow application to the reverse air baghouses utilizing woven fiberglass filter bags. Although fly ash control is the single largest market, there are other industrial baghouse applications where composite nanofiber filtration media can be applied. As the VOC capture is proven, this will expand the CFB opportunity as well as allow for market inroads in a number of other applications such as many areas within the refinery and chemical process industries.

Commercialization: The commercialization effort involves several areas, including intellectual property, strategic partnership, market size and market acceptance, and competition (relative strengths and weaknesses).

The steps to bringing the reactive nanofiber filtration media to market include pilot testing and full-scale demonstrations.

Intellectual PropertyETSVP-JV, LLC is assisting an organization in North Carolina with further development of that organization’s nanofiber filter technology in connection with this EPA SBIR Contract.

Strategic Partnership - A list of candidate partners was developed and contacted this list, and a number of the firms had interest in following up. ETSVP-JV, LLC is actively pursuing a number of parties who currently have expressed interest in the technology.

 

Supplemental Keywords:

nanofilter, gas pollutant, air particulate, contaminated air, volatile organic compound, VOC

SBIR Phase II:

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