LowEmissionAsphalt-136pg-WhitePaper-May2023

P a g e | 110 This is why environmental chemists call photocatalytic carbon and nitrogen sinks “synthetic forests.” 233 The purpose of photocatalytic construction materials for our built environment are to augment and accelerate powerful natural air-purifying processes in places where the landscape has been altered for human consumption and lacks adequate greenspace . As a highly efficient photocatalyst material, TiO 2 234 is a multifaceted photo- responsive mineral 235 ( Figure 69 ) rapidly gaining increased scientific and commercial interest for near-roadway microenvironments as it advances a host of preservation and environmental benefits, including: ✓ Depolluting near-pavement air cleaning applications, where TiO 2 reacted surfaces are able to oxidize a variety of pollutants and contaminants such as those emitted by vehicles. Photocatalytic pavements remove NOx, CO 2, MPP, and VOCs, reducing ozone pollution and greenhouse gas accumulations. Thereby also mitigating acid rain formation. ✓ “Cool Pavement” applications where TiO 2 enhanced pavements provide a solar-reflective top boundary, which lessens pavement related radiative forcing (RF) by reducing pavement heat absorption and averting the convective re-release of solar radiation that leads to the undesired UHI impacts. Significantly lower absorption also extends the life-cycle assessment (LCA) of pavements by slowing-down pavement oxidation. 236 ✓ Super-Hydrophilic / Hydrophobic surfaces, which provide a rapid water- desorbing (faster H 2 O sliding ) pavement surface, making the pavements self- cleaning to remove contaminants (e.g., mold) and staining (de-soiling). The rapid water desorption (TiO 2 hydrophilic surface) protects against water intrusion (hydrophobic pavement subsurface) to extend pavement life. 233 Wilcox J, Carbon Capture, Springer . 234 Certain anatase type nanoparticle (<1 micron) TiO 2 naturally attracts, refracts, and deflects solar radiation efficiently, promoting redox reactions and solar reflectivity. 235 Polymers, Light and the Science of 7 , DuPont TM Ti-Pure ® Titanium Dioxide, DowDuPont, www.dow-dupont.com . 236 Gopalakrishnan K, et al., Climate Change, Energy, Sustainability, and Pavements , Springer, 2014.