Like sodium tungstate (Na?WO?), potassium tungstate is a tungstate composed of an alkali metal, a transition metal, and a non-metal element, exhibiting excellent thermal, mechanical, electrical, and optical properties. It is widely used in chemical and photovoltaic industries. Note: Tungsten is a transition metal element; sodium and potassium are alkali metals with atomic numbers 11 and 19, respectively.
From a chemical composition perspective, potassium tungstate is a compound made of tungsten, potassium, and oxygen. It is an ionic compound formed by monovalent potassium ions (K?) and tungstate ions [(WO?)2?], known in English as potassium tungstate, with the chemical formula K?WO?, molecular weight 326.03, and CAS number 7790-60-5.
From a physicochemical properties standpoint, K?WO? is a colorless or white crystalline powder with a monoclinic crystal structure, 99.5% purity, a density of 3.12 g/mL, a melting point of 921°C, solubility in water, insolubility in alcohol, slight solubility in ammonia, and reactivity with strong acids (except hydrofluoric acid) to form tungstic acid. It also reacts with phosphoric acid or phosphates to produce phosphotungstic heteropolyacid complexes and with organic acids like citric or oxalic acid to form corresponding organic acid complexes. Note: This substance should be stored in a cool, dry place to prevent decomposition.
Regarding production methods, Method 1: Mix potassium dichromate with tungsten powder and heat the reaction to obtain K?WO?. Method 2: React tungsten powder with a potassium hydroxide solution under oxygenated conditions to produce K?WO?. Method 3: Add tungsten oxide to a potassium hydroxide solution, then add a potassium chloride solution, adjust the pH to 3–6, and perform hydrothermal treatment, precipitation, washing, and drying to yield K?WO?.
In terms of applications, beyond its use in producing metallic tungsten powder and tungsten products, potassium tungstate serves as a material for ceramics, a photocatalyst, an analytical reagent, a precipitant for alkaloids, and an additive in the electrolyte of photovoltaic electrochemical cells.
