Grantee Research Project Results
Final Report: Test Protocol for Evaluating Smog Reducing Roofing Tiles
EPA Grant Number: SU835533Title: Test Protocol for Evaluating Smog Reducing Roofing Tiles
Investigators: Cocker, David , Espinoza, Carlos , Liang, Chun-Yu , Rodriguez, Edwin , Moncayo, Jessica , Tam, Kawai , McCoy, Kelly , Lancaster, Louis
Institution: University of California - Riverside
EPA Project Officer: Packard, Benjamin H
Phase: I
Project Period: August 15, 2013 through August 14, 2014
Project Amount: $14,995
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2013) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Awards , Sustainable and Healthy Communities
Objective:
Currently on the market there is a wide variety of roofing tiles designed to help reduce pollution from nitrogen oxides (NOX) in the atmosphere. However, there is insufficient data to support these claims. The objective of this research was to develop a protocol to test titanium dioxide (TiO2) coated roof tiles with the potential to reduce this NOX pollution into components less harmful to people and the environment. The protocol was based on simulating photocatalytic degradation of NOX, which can naturally occur in the environment with a catalyst and sunlight. The apparatus included a miniature environmental chamber, constructed out of wood, Teflon and PVC piping. Sunlight was simulated using UV light. The roofing tile coating was created, composed of glacial acetic acid, water, and the TiO2 catalyst. Tiles were coated with different concentrations so that an optimal TiO2 concentration for the coating could be determined. The tiles were placed inside the environmental chamber, which was then connected to a NOX box, an instrument that reads concentrations of nitrogen oxides, and a calibration gas mixture containing the NOX gas mixture. The gas mixture filled the chamber, with the UV light off, and the system was allowed to reach steady state. Then the UV lights were turned on and concentration readings were taken every five minutes until steady state was reached again or until the NOX concentration reached close to zero. All research was conducted at the Center for Environmental Research and Technology (CE-CERT) at the University of California, Riverside.
Summary/Accomplishments (Outputs/Outcomes):
The previous team found that changes in humidity, light intensity, and temperature did not significantly affect the NOX removal efficiency of TiO2 [1]. To examine the effect of TiO2 concentration on NOX, two purchased Boral clay tiles were coated with different TiO2 surface concentrations, 2.1 g/ft2 for tile 1 and 0.17 g/ft2 for tile 4. The NOX reducing capabilities of the TiO2 tiles were then tested. The tile with the greatest surface concentration, 2.1 g/ft2, was tested first and the average first order kinetic rate constant was 0.1397 min-1 for two trials conducted. NOX concentrations went from 128 parts per billion, ppb, down to 4 ppb in 18 minutes for the first trial. The second trial yielded similar results, concentrations dropped from 165 ppb to 20 ppb in 20 minutes. When the least concentrated tile, 0.17 g/ft2, was tested, the removal efficiency was very similar to that of the highest concentrated tile. Again, two trials were conducted and the average rate constant was found to be 0.1475 min-1. The first trial saw a reduction from 180 ppb to 10 ppb in 22 minutes. A higher initial NOX concentration was used for the second trial to verify the kinetic parameter, which should not be affected by NOX concentration. A concentration of 440 ppb was reduced to 16 ppb in 24 minutes. The two tiles tested exhibited similar reduction efficiencies as well as having consistent rate constants. Surface area is an important factor in the efficiency of the coating because the chemical reaction with NOX occurs only at the catalytic surface. This explains why the reduction in NOX was very similar for the different TiO2 concentrated tiles with the same surface area of the coating.
Conclusions:
We have developed a protocol to effectively evaluate the reduction capabilities of TiO2 coated roof tiles. NOX removal efficiencies ranging from 88 to 97% were achieved. This research was based upon initial findings from the team who won the P3 Phase I grant. Through experimentation using a nonflow through chamber tested in a similar manner described above, they found that parameters such as humidity, light intensity, and temperature did not significantly affect the NOX removal efficiency of TiO2 impregnated roofing tiles [1]. Based upon these results, our team created a TiO2 coating that had the same capabilities as the impregnated tiles.Supplemental Keywords:
air pollution control, Titanium Dioxide, Nitrogen Oxides, criteria pollutants, sustainability, smog reduction, ozone, passive treatmentThe 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.