Photocatalytic concrete for NOx abatement: Supported TiO2 efficiencies and impacts

Abstract

The potential of TiO2-based photocatalysts in mitigating the effects of environmental pollutants is evident in the scientific literature but the large-scale implementation of photocatalytic concretes still appears limited, despite the current global concerns over urban NOx pollution. Improvements in cost-effectiveness are required to enhance the case for a photocatalyst-modified infrastructure and this must address catalyst efficiency, catalyst loading and performance durability. This paper compares photocatalytic efficiencies of TiO2 supported on mortar surfaces with the more conventional TiO2 dispersed in mortar. The influences of environmental conditions, such as NO concentration and flow rate, UVA light intensity and relative humidity, on photocatalytic performance are also investigated using photonic efficiency as an indicator. The supported TiO2 shows greater degradation of NOx (De-NOx), at about 9 times higher than TiO2 powder dispersed in the mortar, ca. 150 times higher utilization efficiency, than that of TiO2 in traditional photocatalytic mortar (with 5% loading).

TiO2-based Photocatalytic Cementitious Composites: Materials, Properties, Influential Parameters, and Assessment Techniques

“…The calcium-silicate-hydrate (C-S-H) gel, which is the main product of cement hydration, can form a dense coating on the surface of TiO 2 and occupy the active sites on the surface of TiO 2 , deteriorating the photocatalytic efficiency. In recently published reports by Yang et al [79,184], they examined the efficiency of supported TiO 2 on quartz sand in degradation of environmental pollutants. They observed that Ti-O-Si chemical linkages were formed, and TiO 2 particles formed uniform layers on the surface of the quartz sand.…”

“…Temperature, relative humidity [79,184], and contact time (surface, flow velocity, height of the air flow over the sample, etc.) would impact the results of the tests.…”

Studying the mix design and investigating the photocatalytic performance of pervious concrete containing TiO2-Soaked recycled aggregates

“…The highest NO degradation rate was achieved at 70%. Compared to the photocatalytic performance of concrete specimens containing TiO2 nano particles in some previous studies, e.g., NO degradation rate at 17.6% in Xu et al (2018), 32%-56% in Mahy et al (2019), and 62% in Yang et al (2019), this study achieved the highest NO degradation rate by adopting TiO2-soaked RCAs in the mix design of pervious concrete.…”

Organic electronic materials for hydrogen peroxide production

“…Photooxidation catalyzed by TiO2 still remains of scientific interest, it also finds real life applications in removal of pollutants by oxidation. For example, titanium dioxide is used in self-cleaning glass 48 or as a component of a concrete 59 , which if used in building elevations, helps to reduce the content of nitrogen oxides in air. As mentioned before, photocatalytic systems are also intensively investigated in light-driven H2 evolution and CO2 reduction reactions, as possible strategies of solar-energy harvesting and removal of atmospheric CO2 34,35 .…”