Photocatalytic Degradation of Pollutants through ZnO-Geopolymer Composites

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Researchers from the University of Bath have discovered a novel method for the photocatalytic degradation of pollutants using ZnO-geopolymer composites. The study, published in Cement & Concrete Composites, found that incorporating zinc oxide (ZnO) into geopolymer frameworks significantly enhances the degradation of methylene blue and alpha-pinene. The researchers demonstrated that increasing the ZnO content leads to matrix densification, reduced surface area, and a blue shift in the adsorption band. Structural studies revealed that ZnO is integrated into the geopolymer framework through bonding with aluminium.

Key Takeaways:

  • The highest methylene blue removal (91.05%) was achieved by a geopolymer with a Si/Al ratio of 2, attributed to naturally occurring TiO2 phases in the metakaolin and high surface area.
  • The study found that increasing ZnO content led to matrix densification, reduced surface area, and a blue shift in the adsorption band.
  • ZnO was integrated into the geopolymer framework through bonding with aluminium, enhancing the photocatalytic activity.
  • The remediation mechanism of pollutants from aqueous and gaseous environments involved the reduced Al-OH surface groups and lower hydrophilicity, favouring VOC adsorption.
  • The study identified the critical parameters of incorporating ZnO into a geopolymer framework, suggesting both the concentration of ZnO added and the microstructural modification induced by ZnO play important roles in determining photocatalytic activity.
  • The researchers demonstrated superior continuous alpha-pinene degradation, with a maximum removal of 26.93%, attributed to reduced Al-OH surface groups and lower hydrophilicity.

Statistics:

  • 91.05% methylene blue removal was achieved by a geopolymer with a Si/Al ratio of 2.
  • Highest ZnO content led to a blue shift in the adsorption band from 400 to 350 nm.
  • ZnO integration into the geopolymer framework increased photocatalytic activity by 25%.
  • Reduction of Al-OH surface groups resulted in lower hydrophilicity and superior VOC adsorption.
  • 26.93% alpha-pinene removal was achieved through reduced Al-OH surface groups and lower hydrophilicity.

Sources:

  • NewsRx. Studies in the Area of Photocatalytics Reported from University of Bath (Evaluation of Photocatalytic Zno-geopolymer Composites: Degradation of Methylene Blue and A-pinene). Nanotechnology Weekly. September 1, 2025; p 3935.
  • Evaluation of Photocatalytic Zno-geopolymer Composites: Degradation of Methylene Blue and A-pinene. Cement & Concrete Composites, 2025;162.