Pathways of conversion of nitrogen oxides by nano TiO2 incorporated in cement-based materials

Ming Zhi Guo, Jun Chen, Men Xia, Tao Wang, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

35 Citations (Scopus)


The ability of photocatalytic cementitious materials to degrade nitrogen oxides (NOx) has been widely used to evaluate their air-purifying function. However, attention has been predominantly placed on the changes in the NOx concentration but the fate of the degradation products is seldom investigated. This study presents a preliminary laboratory investigation on the photocatalytic NOx degradation of nano titanium dioxide (TiO2) incorporated self-compacting glass mortar (SCGM). Focus was mainly placed on the generation and distribution of the degradation products, nitrite (NO2 ) and nitrate (NO3 ), during the NOx removal process. The results showed that the photocatalytic SCGM induced an apparent decrease of NO together with a slight increase of NO2 under UVA irradiation. Meanwhile, the amount of the generated NO2 and NO3 on the surface of the tested samples, in the suspended aerosols, and in the flowing air stream increased as the photocatalytic reaction progressed. The accumulation of NO2 and NO3 on the sample surface led to a slight deactivation effect on the photocatalytic NOx removal ability of the SCGM, which, in turn, slowed down the production of NO2 and NO3 . Interestingly, compared with NO3 , NO2 could more easily be carried away from the sample surface by the flowing air stream. On-site monitoring of the photocatalytic NOx removal activity of the paving blocks produced with the incorporation of TiO2 on the surface layer (Eco-block) confirmed the build-up of NO2 and NO3 with time, which well demonstrated the NOx removal ability of the photocatalytic blocks in real site applications.

Original languageEnglish
Pages (from-to)412-418
Number of pages7
JournalBuilding and Environment
Publication statusPublished - 15 Oct 2018


  • Air-purifying
  • Nitrite and nitrate accumulation
  • Photocatalytic NO removal
  • Recycled glass
  • TiO

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Building and Construction


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