Photocatalytic Functionalized Aggregate: Enhanced Concrete Performance in Environmental Remediation

Amer Hakki* (Corresponding Author), Lu Yang, Fazhou Wang, Ammar Elhoweris, Yousef Alhorr, Donald MacPhee* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
10 Downloads (Pure)


Engineering of effective photocatalytically active structures is of great importance as it introduces a solution for some existing air pollution problems. This can be practically achieved through the bonding of particulate photocatalysts to the surface of construction materials, such as aggregates, with a suitable stable binding agent. However, the accessibility of the photocatalytically active materials to both the air pollutants and sunlight is an essential issue which must be carefully considered when engineering such structures. Herein, different amounts of commercial TiO2 were supported on the surface of quartz sand, as an example of aggregates, with a layer of silica gel
acting as a binder between the photocatalyst and the support. The thus prepared photocatalytically active aggregates were then supported on the surface of mortars to measure their performance for NOx removal. The obtained materials were characterized by electron microscopy (SEM and TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and UV-vis Absorption Spectroscopy. Very good coverage of the support’s surface with the photocatalyst was successfully achieved as the electron microscopic images showed. FTIR spectroscopy confirmed the chemical bonding, i.e., interfacial Ti–O–Si bonds, between the photocatalyst and the silica layer. The photocatalytic activities of the obtained composites were tested for photocatalytic removal of
nitrogen oxides, according to the ISO standard method (ISO 22197-1). The obtained aggregate-exposed mortars have shown up to ca. four times higher photocatalytic performance towards NO removal compared to the sample in which the photocatalyst is mixed with cement, however, the nitrate selectivity can be affected by Ti–O–Si bonding.
Original languageEnglish
Article number28
Number of pages10
Issue number2
Early online date22 Jan 2019
Publication statusPublished - 1 Feb 2019


  • environmental remediation
  • air pollution
  • photocatalytic construction materials
  • nitric oxides
  • functionalized aggregate


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