Thesis Archive
Synthesis of Metakaolin Geopolymer Spheres as Matrix for Nanotitania Photocatalysis using Rice Hull Ash as an Activator
Lazaro, Sean Andrei I.
Abstract:
Geopolymers are a prominently studied sustainable material as a potential substitute for ceramic materials but with a significantly reduced carbon footprint. Geopolymer synthesis is primarily achieved through the chemical activation of aluminosilicate materials using alkaline activating solutions to form the inorganic polymeric network. Synthesis of geopolymer spheres which can be used as porous matrices for nanomaterials is one of the novel applications. This study utilizes metakaolin as the raw material for geopolymer sphere synthesis which will be used as porous matrices for nanotitania photocatalysis. Moreover, the replacement of sodium silicate activator with a silicate activator extracted from rice hull ash is part of the study. Different mix proportions by replacement of rice hull ash activator and addition of nanotitania was involved in the study. The setting time, density, open porosity, and water absorption of the spheres at different mix proportions were measured. Characterization through SEM, XRD, and FTIR was also performed. The replacement of the silicate activator with rice hull ash activator did not have significant effects to the properties of the geopolymer spheres barring setting time. Therefore, replacement of rice hull ash activator up to 20% for geopolymer synthesis is feasible. Methylene blue was chosen as the model pollutant to test the photocatalytic activity of the synthesized materials. The nanotitania-coated geopolymer spheres degraded the dye solution with the extent ranging from 29% to 73%. Furthermore, the geopolymer spheres without nanotitania were able to degrade the methylene blue solution. The synthesized geopolymer spheres were acceptable support matrices for the photocatalytic activity of nanotitania.
Adviser:
PROMENTILLA, Michael Angelo B.