Synthesis of geopolymer spheres with photocatalytic activity

¹ Department of Chemistry, College of Science, De La Salle University, 2401 Taft Avenue, Manila 1004, Philippines
² Department of Chemical Engineering, Gokongwei College of Engineering, De La Salle University, 2401 Taft Avenue, Manila 1004, Philippines

Corresponding author: michael.promentilla@dlsu.edu.ph

Abstract

Geopolymer is an emerging “green” cementitious material which has a potential to valorize waste such as rice hull ash (RHA). Geopolymer is a kind of alkali-activated material which forms from the reaction of alumino-silicates in an alkaline solution. This study uses RHA as the raw material for alkaline activator while metakaolin (MK) serves as a geopolymer precursor to synthesize the so-called geopolymer sphere. Then its capacity as a porous matrix was explored upon incorporation of TiO₂ nanomaterial using horizontal vapor phase growth (HVPG) technique to enhance its photocatalytic property. Indication suggests that the synthesized MK-geopolymer spheres activated with RHA-based water glass solution (WGS) were comparable to that of commercial WGS. Furthermore, the geopolymer spheres were successfully coated with TiO₂ in the form of nanocrystals. Its photocatalytic activity was evaluated in terms of methylene blue degradation. This material’s potential environmental application for water purification and wastewater treatment will be investigated for future works.