Sodium metasilicate pentahydrate (CAS 10213‑79‑3) is a granular alkaline reagent Na₂SiO₃·5H₂O, widely used in pulp and detergent manufacturing. Chemically it belongs to the family of water‑soluble silicates, where the SiO₄⁴⁻ tetrahedral units are linked into polymeric chains and the five water molecules are incorporated as crystalline hydrate. When dissolved, the hydrate dissociates to give sodium hydroxide and soluble silicate species, which explains the very high alkalinity (pH ≈ 13 at 1 % solution) and the rapid neutralisation of acids. In the pulp‑paper sector the metasilicate is employed not only as a bleaching aid but also as a fibre‑pre‑treatment agent. It swells the cellulose matrix, disrupts hemicellulose linkages and improves the penetration of oxidative bleaching chemicals such as chlorine dioxide, hydrogen peroxide or peracetic acid, thereby increasing reaction rates and reducing the formation of undesirable metal‑based precipitates. The silicate also buffers the alkaline bath, maintaining a stable pH and preventing scale formation on equipment. In detergent formulations metasilicate is typically combined with sodium carbonate, sodium sulfate and polymeric surfactants; it enhances fat emulsification by forming silicate‑fat complexes that remain dispersed under low‑temperature washing conditions, allowing lower surfactant dosages and better soil removal. For water treatment it acts as a corrosion inhibitor, creating a thin amorphous silicate film on metal surfaces, and it complexes calcium and magnesium ions, mitigating scale deposition. The product is approved for food‑contact applications such as cleaning of packaging, processing of fruits and vegetables, and removal of surface residues without affecting organoleptic properties. The granules must be stored in a dry, cool environment, protected from moisture and direct sunlight; polypropylene bags preserve their physical integrity and prevent caking. During handling protective gloves and goggles are recommended, as the high pH can cause skin and eye irritation. When diluted with water the exothermic reaction remains modest, with temperature not exceeding 30 °C, which simplifies temperature control in large‑scale processes.
| Формула | Na₂SiO₃·5H₂O |
| Na₂O | 29.3 ± 1.0% |
| SiO₂ | 28.4 ± 1.4% |
| pH (1%) | ≈ 13 |
| Растворимость | Полная в воде |
25 kg bags / 500–1000 kg big bags
Sodium metasilicate pentahydrate must be stored in a dry, well‑ventilated area protected from direct sunlight and moisture. Recommended storage temperature is between +5 °C and +25 °C; higher temperatures may accelerate hydrate degradation. When the packaging remains intact, the typical shelf life is up to 24 months. Handling requires protective gloves and safety goggles, avoiding skin contact and inhalation of dust. Ensure the container is tightly sealed and free of damage or moisture ingress to maintain product quality.
