Fabrication of porous geopolymers from coal fly ash and spodumene flotation tailings through a novel combined saponification/hydrogen peroxide process.

The objective of this investigation is to overcome the difficulties in fabricating cost-effective, eco-friendly porous geopolymers (PGs) by integrating Coal fly ash (CFA) and spodumene flotation tailings (SFT). This synthesis utilizes a unique blend of CFA and SFT in a 6:4 mass ratio, with specific attention to optimizing the pore architecture to improve the PGs' efficacy. Key parameters included a modulus of 1.6, a 3.3 wt% concentration of hydrogen peroxide, 2.2 wt% olive oil, and a curing temperature of 70°C. This protocol achieved a PGs with a porosity of 72.8%. Analyses indicated that the PGs predominantly comprised quartz (SiO₂), albite (NaAlSi₃O₈), and microcline (KAlSi₃O₈), with albite being the most prevalent at 52%, and quartz at 34.6%. In contrast, unfoamed geopolymers (UGs) showed a dominance of microcline at 36.9%, with quartz being the next major constituent. Despite the similarities in mineral composition between PGs and UGs, the addition of hydrogen peroxide and olive oil markedly modified the pore configuration in PGs, transforming their structure into a uniformly porous one with mesoporous properties, including a pore size distribution of 2-50 nm and a specific surface area of 15.59 m/g. The creation of CFA-SFT-based geopolymers involves several stages, such as gas production, saponification, and polymerization reactions. This research not only establishes a scientific foundation for using CFA and SFT as resources but also paves the way for manufacturing high-performance, cost-efficient porous geopolymer materials.