One-step synthesis of ordered mesoporous silica from olivine and its pore size tailoring

This study investigates the reaction of sulfuric acid with olivine for the synthesis of long-range ordered mesoporous silica at low-temperatures. By synthesizing mesoporous silica directly from olivine, no high temperatures or reactants with a high CO₂ footprint are required. The silicic acids released from olivine are directly guided to form high quality ordered mesoporous silica in a one-step synthesis with the use a micellar liquid crystal prepared from the non-ionic surfactant Triton X-100. The produced mesoporous structures feature specific surface areas of up to 1000 m²/g and narrow pore size distributions around 2–4 nm. In addition, the optimal conditions and the limits of the preparation method are investigated. It was shown that Triton X-100 concentrations between 20 and 30% and olivine contents between 10 and 20% are the optimal conditions. Moreover, the washing process of the product is investigated, resulting in high silica purities. Furthermore, the pore size can be tailored into larger sizes with the addition of heptane. Therefore, olivine can be a green alternative source for the synthesis of well-tailored ordered mesoporous silica.