Final Report: Indoor Air Purification via Low-Energy, In-situ Regenerated Silica-Titania Composites

EPA Contract Number: EPD09034
Title: Indoor Air Purification via Low-Energy, In-situ Regenerated Silica-Titania Composites
Investigators: Casasus, Anna I
Small Business: Sol-gel Solutions, LLC
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: February 1, 2009 through September 11, 2009
Project Amount: $69,795
RFA: Small Business Innovation Research (SBIR) - Phase I (2009) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR)


Sick building syndrome, used to describe acute negative health effects linked to time spent in a building, has been related to poor indoor air quality. Similarly, poor aircraft cabin air quality has been identified as a cause of negative health effects in pilots and flight crews, leading to numerous studies on aerotoxic syndrome. Symptoms range from minor irritation and headaches to disorientation, nausea, and seizures. These symptoms can pose a serious threat if experienced by pilots and/or crew during flight.
Volatile organic compounds (VOCs) are a major source of indoor air pollution. Technologies that can safely, economically, and effectively degrade VOCs from indoor air are necessary to protect human health. Silica-Titania Composites (STCs), an innovative technology developed at the University of Florida, have been successfully demonstrated in bench- and pilot-scale tests for the removal of VOCs from air and have been commercialized for gas-phase mercury removal at a chlor-alkali facility.  Sol-gel Solutions, LLC (Sol-gel) has licensed the technology for commercialization.
Although the STCs are well suited for numerous indoor air applications, this EPA SBIR project focused on a system for purification of aircraft cabin air using the STCs in a manner that will minimize energy input and oxidation byproduct generation in closed environments. The current norm is to use sorbent filters, which simply transfers a gas-phase contamination problem to the solid phase. These filters are bulky, and must be disposed of when saturated. The STCs can not only adsorb, but also oxidize VOCs when irradiated with UV light, resulting in regeneration of the STCs for reuse numerous times.
The initial target market is the airline industry because the need is most pressing in this arena. This system, however, would work equally well for residential and commercial indoor air purification.
The scope of work included determining the STC adsorption capacity, the required regeneration frequency and duration, and the quantification of oxidation byproducts. Additionally, Life Cycle Assessment (LCA) of the proposed system was completed. Because of the low energy requirement, long lifetime, and simple regeneration, the STC technology promises to be preferable to other technologies. 

Summary/Accomplishments (Outputs/Outcomes):

The Phase I research resulted in the following findings:
  • A 0.1 s contact time was sufficient to achieve the target ethanol removal (average 75%) for 20 hours.
  • A 30-minute regeneration without sweep air was sufficient to restore the adsorption ability of the regenerated STCs to that of virgin STCs.
  • Minimal oxidation intermediates were produced during regeneration, and the incorporation of sweep air during regeneration reduced this production.


The following conclusions were reached at the end of the Phase I research: 
  • The proposed STC system for aircraft cabin air purification is very effective under conditions specified for aircraft cabins.
  • There is significant interest within this market for a commercial solution.
  • Based on LCA of the STCs versus granular activated carbon for this application, the STC system appears to have less impact on the environment.
  •  Commercialization:
Sol-gel Solutions has been in discussions with various contacts in the industry, including Pall Corporation and Boeing regarding commercialization of the STC technology for aircraft cabin air purification. There is a pressing need for a solution within this market at the present time, and this is a great platform for transitioning into commercial solutions for residential and commercial building air purification. As Sol-gel would prefer to remain a research and development firm rather than a system manufacturer, the preferred approach for commercialization would be to license the technology to a large company within these markets.

Supplemental Keywords:

small business, SBIR, EPA, indoor air purification, silica-titania, silica-titania composites, sick building syndrome, indoor air quality, aircraft cabin air, aerotoxic syndrome, volatile organic compounds, VOCs, indoor air pollution, human health, mercury removal, UV light, adsorption, oxidation, oxidation intermediates, contaminant, pollutant removal, irradiation, airline industry, residential air quality, life cycle assessment, low energy requirement, regeneration