Fabrication of Geopolymer from Fly Ash: Its Performance as Fire-Resistant Material and Dye Removal from Aqueous Solution
摘要
The present work focuses on studying the composition, microstructure as well as physical and mechanical properties of geopolymer fabricated form hazardous fly ash. Moreover, its applications as fire-resistant material and dye-removal from aqueous solution are also the main goals of this study. Geopolymer pastes were fabricated using fly ash and alkali activator solution, and then kept at 70 °C for 24 hrs. Finally, the prepared pastes were cured in air for 28 days. To study the fire-resistance, some samples of cured geopolymers were subjected for firing at 300, 600 and 900 °C. The dried and/or fired geopolymers were investigated for their phase composition, microstructural analysis, physical properties (bulk density and apparent porosity), thermal analysis and compressive strength. Moreover, the dried geopolymer powder was used to remove methylene blue dye (MB) form aqueous solution. The removal efficiency was measured at different pH values and various dye concentrations with studying the suitable adsorption isotherm model. The results revealed that high performance geopolymer with good physical properties (AP: 22% and BD: 1.69 g/cm3) and excellent compressive strength (46 MPa) was prepared from fly ash after curing 28 days. Furthermore, the geopolymers subjected to firing at 300, and 600 °C gave relatively lower compressive strength values (25 and 23 MPa, respectively) than the dried one due to the dehydration and dehydroxylation of geopolymers. On the other hand, the geopolymer fired at 900 °C, exhibited good compressive strength (37 MPa) due to the densification by liquid phases. Good removal efficiency (95%) of MB dye (at 10 mg/l) was obtained after applying the dried geopolymer as adsorbent. The adsorption process was followed by and fitted with Langmuir isotherm model.