- Sodium molybdate (Na₂MoO₄) is an inorganic compound consisting of sodium (Na⁺) and molybdate (MoO₄²⁻) ions. It typically occurs as a white, crystalline powder or colorless crystalline solid, often in its dihydrate form (Na₂MoO₄·2H₂O). This compound is highly soluble in water and forms clear, alkaline solutions. Sodium molybdate is valued for its chemical stability, low toxicity in small quantities, and its role as a source of the essential trace element molybdenum (Mo) in a variety of applications.
- In agriculture, sodium molybdate is widely used as a micronutrient fertilizer, particularly for leguminous crops like soybeans, peas, and alfalfa. Molybdenum is a crucial component of enzymes involved in nitrogen fixation, such as nitrogenase and nitrate reductase. Supplementing soil with sodium molybdate enhances plant metabolism, promotes protein synthesis, and increases overall crop yield, especially in acidic or molybdenum-deficient soils. It can be applied directly to the soil, used in seed treatment, or included in foliar sprays.
- In industrial and chemical applications, sodium molybdate serves as a corrosion inhibitor, especially in closed-loop cooling systems and metalworking fluids. It provides effective protection for metals like steel and copper alloys by forming a passivating layer that prevents oxidative degradation. Unlike some traditional corrosion inhibitors, sodium molybdate is considered less toxic and more environmentally friendly, making it a preferred alternative in systems where safety and sustainability are concerns.
- In the laboratory and research setting, sodium molybdate is used in analytical chemistry and molecular biology. It plays a role in colorimetric assays to detect phosphate or silicate ions, forming colored complexes that can be measured spectrophotometrically. Additionally, it is used in enzyme inhibition studies and buffer formulations, particularly in the stabilization of some enzymes and protein complexes during electrophoresis or chromatography.
- Sodium molybdate also finds applications in ceramics, pigments, and electroplating. In ceramics and glass manufacturing, it acts as a flux to improve melting behavior and material homogeneity. In pigments, it may be included as a component in molybdate orange, a corrosion-resistant pigment for coatings and paints. It is also used as an additive in lubricants, where it reduces friction and wear in mechanical systems.
- In health and nutritional contexts, molybdenum is an essential trace element for humans and animals, required for enzymes such as xanthine oxidase, aldehyde oxidase, and sulfite oxidase. Though sodium molybdate can be used as a dietary supplement in animal feed, its intake must be carefully controlled—excessive molybdenum can interfere with copper metabolism, leading to deficiency symptoms in livestock.
- Despite its relative safety compared to other industrial compounds, sodium molybdate should still be handled with care. Prolonged or excessive exposure can lead to respiratory irritation, and ingestion of high doses may cause gastrointestinal upset or toxic effects in animals. In environmental contexts, it poses a moderate risk to aquatic ecosystems if released in large quantities.
