Scalable synthesis and comprehensive characterization of nanostructured silica derived from Ethiopian pumice for high-performance rubber applications

Abstract The growing demand for sustainable, high-performance rubber materials motivates the development of eco-friendly silica fillers. This study presents a scalable synthesis of nanostructured silica from Ethiopian pumice via beneficiation, alkaline extraction, and optimized sol–gel precipitation. Key synthesis parameters; reaction temperature (60–90 °C), precipitation pH (7–9), and calcination temperature (600–750 °C); were systematically varied. Comprehensive characterization (FTIR, XRD, BET, XRF, XPS, TGA, SEM, EDS, HR-TEM) established correlations between synthesis conditions and properties critical for rubber reinforcement. Optimized samples indicated excellent properties for rubber reinforcement. P2-SiO2 (synthesized at:75 °C, 650 °C, pH 8.5) showed 95.27% SiO2 purity, nanoscale particle size of 115.54 nm, uniform morphology with moderate agglomeration, surface area of 402 m2/g, mesopore diameter of ~ 3.0 nm, reactive silanol groups, and thermal stability up to 800 °C. P3-SiO2 (synthesized at: 85 °C, 700 °C, pH 8.5) demonstrated slightly higher performance, with 95.63% SiO2 purity, particle size of 99.43 nm, uniform non-agglomerated morphology, surface area of 468 m2/g, mesopore diameter of ~ 3.2 nm, reactive silanol groups, and thermal stability up to 800 °C. Among the samples, P3-SiO2 confirmed the most favorable combination of properties, making it a promising industrially scalable filler for high-performance rubber composites. In contrast, the Eco-Templated and sub-optimal samples (P1-SiO2 and P4-SiO2) showed lower SiO2 purity, larger particle sizes, irregular morphology, and pronounced agglomeration, reducing their reinforcing effectiveness. These findings demonstrate that Ethiopian pumice is a sustainable source of cost-effective, high-performance silica, and further work on scale-up and surface functionalization is recommended to enable industrial applications.