Grantee Research Project Results
Final Report: High efficiency and low-pressure filter with bioinspired nanostructured material coating
EPA Contract Number: 68HERC240016Title: High efficiency and low-pressure filter with bioinspired nanostructured material coating
Investigators: Shirman, Tanya
Small Business: Metalmark Innovations, PBC
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2023 through May 30, 2024
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2024) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , Air Quality and Air Toxics , Air , Wildfires
Description:
Over recent decades, the Western US and Canada have experienced a marked increase in the frequency and intensity of wildfires, posing an escalating environmental and health threat. Wildfires discharge a multifaceted array of pollutants, including volatile organic compounds (VOCs) and various particulate matter (PM). These wildfire emissions can traverse continents, leading to PM concentrations that far surpass safe health thresholds. Numerous studies demonstrate that most PM emitted from wildfires are in the sub-micron size range, typically below 300 nm (PM < 0.3 μm). Exposure to wildfire smoke has adverse health effects, such as an increase in mortality and respiratory morbidity, increased rates of cardiovascular mortality and hospital admissions for ischemic heart disease. Another feature of sub-micron PM is that it stays suspended in the air substantially longer than larger particulates, travels long distances, and easily infiltrates inside buildings.
Current solutions for indoor air purification rely mainly on ventilation with outdoor air and the installation of filters into Heating Ventilation and Air Conditioning (HVAC) systems. HVAC filters represent the dominant means for PM removal in both residential and commercial indoor environments. Their rating is based on their minimum removal efficiency for three broad particle size bins (0.3–1, 1–3, and 3–10 μm). The minimum removal efficiency value among these three size bins is then used to assign an HVAC filter its efficiency rating, called the Minimum EfficiencyReporting Value (MERV) per ASHRAE Standard 52.2. MERV 8-10 are commonly found in commercial and residential HVAC systems. To increase protection against wildfire smoke, the general recommendation is to upgrade HVAC filters to MERV 13. However, an increase in the MERV grade comes at the cost of higher pressure, which means expensive capital and operating costs with high energy consumption. Furthermore, typical HVAC filters are inefficient for the removal of sub-micron PM, especially for smoke particles, which are < 300 nm.
In our EPA Phase I project, we leveraged our patent-pending bioinspired materials platform to develop and validate scalable nanostructured filter media coatings on MERV 8–11 substrates. Our goal was to enhance filtration efficiency by up to 100% while limiting back pressure increase to less than 50%. Specifically, we targeted the submicron particle size range (<1 μm, PM1.0), where filters typically encounter their MPPS and face challenges in wildfire smoke removal. We formulated coatings, established testing setups, and evaluated over 16 filter media types, including polymeric and fiberglass, from four leading manufacturers.
Summary/Accomplishments (Outputs/Outcomes):
The key achievements of this EPA Phase I project include:
Composite Filter Media Development: We successfully created a composite filter media by applying a novel multifunctional coating to common media substrates. This coating demonstrates good adhesion properties and no shedding.
Streamlined Testing Process: Upgrading our smoke filtration test setup and automating processes led to consistent and reproducible experimental conditions. This reduced human error and allowed easy customization of testing parameters. As a result, we developed robust Standard Operating Procedures (SOPs) for pine needle smoke (surrogate for wildfire smoke) generation and filtration testing.
Filtration Efficiency Improvement: This coated media demonstrated up to a 40% increase in filtration efficiency for smoke particles while maintaining a minimal pressure increase. Importantly, the coated media exhibited good performance stability even after aging, a critical attribute for real-world applications. In addition, we extensively characterized various commercial media for PN smoke removal efficiency. Notably, we discovered significant drawbacks of electret media (regardless of MERV rating) in protecting against wildfire smoke.
Conclusions:
The successful implementation of the materials and coatings developed during this Phase I project could lead to improvements in air filtration efficiency, system simplification, and reduced cost and energy usage. These achievements were realized through the following:
Rationally Designed Coating Morphology and Filtration Efficiency Improvement: Our coating design enhances the removal efficiency of smoke particulates.
Minimal Pressure Drop Increase: By minimizing the pressure drop increase of the coating, we decrease energy consumption (compared with filter upgrades) and lifetime costs for filtration systems.
Cost-Effective Materials and Coating: We utilize low-cost chemical precursors and scalable synthetic procedures, resulting in cost-effective finished filter products.
The Phase I outcomes pave the way for a highly effective, competitively priced, and energy-efficient solution to protect against growing threats of wildfire smoke pollution in occupied or semi-closed spaces, including schools, medical facilities, universities, offices, hotels, and residential homes.
Commercialization:
The project's success advances the commercial feasibility of low-cost and low-energy filters for providing people with the necessary protection against wildfire smoke. Commercial adoption may include integrating the new filters into the Metalmark self-cleaning air purifiers or selling pleated filters as direct HVAC filter replacements.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 2 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Shirman T, Shirman E, Liu S. Evaluation of Filtration Efficiency of Various Filter Media in Addressing Wildfire Smoke in Indoor Environments:Importance of Particle Size and Composition. Atmosphere. 2023 Nov 24;14(12):1729. |
68HERC240016 (Final) |
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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.