A novel synthesis of solid Na-silicate based on Si-rich diatomite waste

[Display omitted] •Alternative waste-based sodium silicate was synthesized.•Si-rich diatomaceous earth with high surface area (5.344 m2/g).•Post-synthesis product presented 95.33% sodium silicate (Na2SiO3).•Waste valorization for sustainable materials design. Sodium silicate is widely used in industry, and its production typically depends on traditional raw materials and high energy consumption. The present study investigated the synthesis of an alternative Na-silicate based on diatomaceous earth waste. The Si-rich waste exhibited a high surface area and porosity. Diatomite waste and NaOH were used as reagents, and the synthesis route was carried out by wet method and thermal treatment at 400 °C. The synthesis product presented more than 90 % Na2SiO3, and Si-O-(Na) type bonds were observed. These findings may be useful in the development of sustainable and high-value-added materials obtained by the waste valorization.