Grantee Research Project Results

2021 Progress Report: Perstraction for the Removal of PFAs from Water

EPA Grant Number: SU840161
Title: Perstraction for the Removal of PFAs from Water
Investigators: Almquist, Catherine B , Sanus, Ibrahim , Badahman, Akram , Hanzel, Samantha , Jung, Will , Neal, John , O’Hare, Isabelle , Garza, Linda
Current Investigators: Almquist, Catherine B , Garza, Linda , Marcellino, Chris , Chen, Sean , Armstrong, Ryan , Flood, Megan , Goddard, Tai
Institution: Miami University - Oxford
EPA Project Officer: Spatz, Kyle
Phase: I
Project Period: December 1, 2020 through November 30, 2021 (Extended to November 30, 2022)
Project Period Covered by this Report: December 1, 2020 through November 30,2021
Project Amount: $24,979
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources

Objective:

Our ultimate goal is to develop a cost-effective and technologically feasible prototype that would be incorporated into an automobile to reduce evaporative fuel vapor emissions by at least 70% compared to current fuel vapor emission control systems. Three design parameters on which Phase 2 efforts will be focused are: 1) the size and construction of the cylindrical prototype, 2) the durability of the photocatalytic film, and 3) the power, intensity, and distribution of the UV LEDs. The size of the “next generation” prototype will be a cylindrical prototype with diameter of 3 cm and length 10 cm, a size and shape that was suggested by Stant Manufacturing to facilitate its incorporation into the existing ORVR systems. The Phase II objectives and strategies are to: 1) Construct a cylindrical UV LED photocatalytic fuel vapor emissions control device that is 3 cm diameter by 10 cm in length, a size that can fit into the current ORVR system; 2) Demonstrate a photocatalytic film that is durable to abrasion and vibrations and when exposed to water; 3) Identify and assess the limitations of this technology for the following experimental variables: the intensity of the UV LEDs at the photocatalytic film, the illuminated area and type of photocatalytic film, residence time, concentration and type of hydrocarbon, UV LED intensity and wavelength, humidity, and the longevity of service life of our device; 4) Demonstrate the operation of the prototype in standard test systems; 5) Conduct an economic analysis for the proposed technology to assess economic attractiveness from multiple perspectives (auto manufacturers, human health, regulations); and 6) Design and develop educational and marketing tools for this technology.

Progress Summary:

Progress toward each of the objectives was made in the first year of our Phase 2 efforts. Cylindrical prototypes have been designed and fabricated from aluminum, with UV LEDs secured to the inside of the outer tube and a photocatalytic film adhered to the outside of the inner tube of the annulus reactors. Two different lengths of the prototypes were constructed to assess the effects of residence time and illuminated surface area in otherwise identical reactor designs. A method to coat an inner cylinder in the prototype devices with commercially-available TiO2 photocatalyst was developed based upon a modified dip-coating method. Using a combination of heat and a relatively high concentration of TiO2 in an alcohol, a smooth coating of photocatalyst can be formed on an aluminum rod, which is used within the prototype devices. ZnO/TiO2 composites from sol-gel methods were investigated in an effort to improve upon the durability and photocatalytic activity of the photocatalytic film, but the ZnO/TiO2 composites were found to be less active than pure TiO2. A possible reason for this observation is a higher rate of electron-hole recombination in the ZnO due to its much larger crystal size than that of TiO2. Two different chemicals have been investigated as representative fuel vapors: ethanol and hexane. Significant differences in extent of degradation was observed between ethanol and hexane vapors in our prototypes, where ethanol degrades much more readily than hexane. Two likely reasons for this observation include: 1) the higher stoichiometric ratio of O2/hydrocarbon required to completely oxidize hexane than that of ethanol, and 2) the more likely partial oxidation products of hexane will adhere to the photocatalytic surface than those of ethanol. The effect of humidity was investigated and was found to only slightly lower the observed degradation of ethanol and hexane vapors in our test systems. UVC LEDs were compared with UVA LEDs as light sources within our test systems. While the wavelengths of the UVC LEDs were shorter than those of UVA LEDs (hence higher energy), the intensity of the UVC LEDs that were purchased was significantly lower than that of the UVA LEDs. Therefore, the performance of the device with UVC LEDs was not as attractive as that with UVA LEDs. The longevity of the performance of the prototype devices was assessed for one month, and the performance of the reactor appears to degrade only slightly after one month online. We are currently assessing the effects of cycling on-off operation, which may be more representative of the device in its intended application.

Future Activities:

Future activities will include the fabrication and performance assessment of a lighter-weight prototype device with a durable photocatalytic film and lower power requirements. Focus will be placed on creating a durable photocatalytic film within the device, subjecting the device to gasoline vapors in lab as well as to standard test methods to assess performance in an automobile, an economic assessment of the device from multiple perspectives, and the development of a website and educational and marketing tools for the technology.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this project

Supplemental Keywords:

UV LED, photocatalysis, fuel vapors

Relevant Websites:

AlChE Midwest Regional Conference Exit , US EPA P3: UV LED Photocatalytic Evaporative Fuel Vapor Emission Reduction Device Exit

Progress and Final Reports:

Original Abstract

Final Report