Improved photocatalytic nitrogen oxides removal using recycled glass-nano-TiO2 composites with NaOH pre-treatment

Ming Zhi Guo, Jiang Shan Li, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

24 Citations (Scopus)


The use of waste glasses as aggregates in cementitious materials provides a viable recycling option to alleviate the burden on landfills in Hong Kong. More interestingly, the light-transmitting properties of glass are beneficial to augment the TiO2-mediated photocatalytic activity. This study attempted to take full advantage of glass aggregate (GA) by attaching nano TiO2 particles on its surface. NaOH etching was employed to pre-treat the surface of GA in order to increase its surface area before TiO2 particles were attached. The experimental results showed that the treatment of NaOH etching effectively induced cracks and pores on the initially smooth surface of GA. As a result, a higher amount of nano TiO2 particles (0.0434 g per 50 g of GA) were attached/absorbed on the surface of the treated GA compared to the untreated analogue (0.0224 g per 50 g of GA) when immersed in 10 g L−1 TiO2 solutions. More importantly, the higher TiO2 absorption ability of the treated GA translated into a higher photocatalytic NOx removal activity. Compared with the untreated GA-TiO2 composites, the NaOH etched GA-TiO2 composites (immersed in 1 g L−1 TiO2 solutions) experienced an approximately 60% increase in the photocatalytic NOx removal efficiency. The overall findings revealed that compared with the sand-TiO2 composites, the NaOH etching treated GA-TiO2 composites not only garnered the beneficial effect from the light-transmitting of glass but also had the beneficial etching effect of NaOH treatment. Therefore, the developed NaOH etched GA-TiO2 composites hold great potential for applications in cementitious photocatalytic materials.

Original languageEnglish
Pages (from-to)1095-1104
Number of pages10
JournalJournal of Cleaner Production
Publication statusPublished - 1 Feb 2019


  • Air-purifying
  • Glass-TiO composites
  • Nano materials
  • Photocatalytic NO removal
  • Recycled glass

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Strategy and Management
  • Industrial and Manufacturing Engineering


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