Porous geopolymer with k-based and na-based activator using teepol surfactant as foaming agent

• Main Author: Anatasha Esther Gerald
• Format: Academic Exercise
• Language: English
• Published: 2015
• Subjects: QD Chemistry
• Online Access: https://eprints.ums.edu.my/id/eprint/18962/1/Porous%20geopolymer.pdf; https://eprints.ums.edu.my/id/eprint/18962/

Geopolymer technology is presented with the aim to introduce the materials that may be synthesized by alkali-activation of aluminosilicates. Highly porous geopolymers with homogenous microstructure were fabricated by gelcasting. The effects of surfactants on microstructure of porous geopolymer were investigated. The synthesis process of porous geopolymer was generated from meta kaolin, alkaline activator solutions (K-based and Na-based) and Teepol surfactant as foaming agent. The role of surfactant in this study is to stabilize the wet foams by decreasing the surface tension of the system. The particle size and size distribution of the geopolymer foams were adjusted by the control of surfactant content at 4 wt% and 10 wt% with respect to total weight. The foams were evaluated only after heat treatment at 80°C, which was conducted in order to complete the geopolymerization reactions. Lastly, the sintering of porous geopolymer was done at 500°C, 700 °C and 900°C to investigate the thermal cracks distribution of porous geopolymer. The porous geopolymer was then characterized using SEM, FTIR, TGA and XRD. The results showed that increasing surfactant content favors the adsorption at gas/liquid interface, thereby promoting foaming. TGA analysis showed that the dehydroxylation of kaolin occurs at temperatures above 450°C. The octahedral sheet loses water and decomposed into disordered meta phase during dehydroxylation between 450°C and 800°C. In FTIR spectrum, OH stretching around 3700 cm-1 to 3620 cm-1 doublet was shown to be the characteristic for the raw material, kaolin. The raw material contains 72 wt% kaolin, 27 wt% quartz and minor amount of other components in accordance to XRD data. Overall, the morphology, strength and thermal resistance of the porous geopolymer suggest that they could be employed as low cost replacement for highly porous ceramics in applications such as catalysis supports, adsorption and separation, filtration of hot gases and refractory insulation of furnaces.