Immobilization of TiO2 Photocatalysts for Water Treatment in Geopolymer Based Coatings

This study presents a simple and sustainable coating technology for the deposition of photocatalytic coatings based on titanium dioxide and geopolymers, which requires no thermal post-treatment. Titania powder P25, potassium silicate and a calcium aluminate-based hardener were dispersed in water and applied to aluminum substrates using a paintbrush, a roller and a spray gun. The coatings were air-dried for 12 h. The photocatalytic activities were tested via degradation of an aqueous methylene blue solution in a batch reactor under artificial UV-A light. The roller and the spray gun-based coatings yielded well-adhering coatings with high photocatalytic activity. Brushed coatings were inhomogeneous and unstable. The presented method of producing photocatalytic coatings is very simple to apply and does not require complex technologies or energy-intensive thermal treatments.