Main Uses of Phosphoric Acid

Phosphoric acid(H3PO4), phosphorous acid(H3PO3), and hypophosphorous acid(H3PO2) are inorganic acids widely used in various sectors of the national economy. Phosphoric acid, in particular, is used more extensively and in larger quantities than phosphoric acid and hypophosphorous acid in different industries. Phosphoric acid (H3PO4) can be used in the detergent, food, pharmaceutical, pigment, electroplating, and rust prevention industries. It can be used as a phosphate raw material, metal surface treatment agent, organic reaction catalyst, refractory material additive, and activated carbon treatment agent.

In the daily chemical industry, phosphoric acid(H3PO4) is used as an auxiliary agent in the production of detergents; in the food industry, it is used as an acidic flavoring agent; in the fermentation industry, it is used as a yeast nutrient source; and in the pharmaceutical industry, it is used to manufacture glycerol, sodium phosphate, nervous system drugs (ferric phosphate), dental adhesives (zinc phosphate), dental materials (calcium hydroxyphosphate), and as a pH adjuster for penicillin.

In the electronics industry, phosphoric acid(H3PO4) can be used as a cleaning agent (to remove impurities from silicon wafers and integrated circuit products) and an etching agent. In the plastics industry, it is used as a catalyst for the condensation reaction of phenolic resins. In the metallurgical industry, phosphoric acid is used to produce refractory mortar, extending the lifespan of steelmaking furnaces. In metal surface treatment, phosphoric acid is used for rust removal, rust layer conversion, and phosphating, significantly improving the adhesion of anti-rust coatings and the appearance quality of machinery. Phosphoric acid is used in chemical polishing, greatly enhancing the corrosion resistance of aluminum products and improving finishing effects.

Phosphoric acid(H3PO4) can replace sulfuric acid in catalyzing certain esterification reactions, increasing yields and improving working conditions. Food-grade phosphoric acid and food-grade phosphate additives not only improve food quality but also supplement the body with essential phosphorus. Thermal phosphoric acid is classified into industrial, food-grade, reagent-grade, and electronic-grade based on its purity. Industrial-grade phosphoric acid is generally available in 75% and 85% H3PO4 specifications. Approximately 80% of phosphoric acid is used to produce various phosphates, including sodium, potassium, calcium, zinc, and aluminum salts, as well as polyphosphates and double phosphates.

Food-grade phosphoric acid(H3PO4) is mainly used in the pharmaceutical, sugar, and food industries. Besides direct consumption in the food industry (acidulants and yeast nutrients in cola, beer, candy, salad oil, dairy products, etc.), most phosphoric acid is used to produce various food-grade phosphates, including sodium, potassium, calcium, zinc, and aluminum salts, as well as polyphosphates and double phosphates. Reagent-grade phosphoric acid is commonly used as an analytical reagent. Electronic-grade phosphoric acid is mainly used as a cleaning agent and etchant for semiconductor discrete devices, and also as a material for glass surface treatment and cleaning of liquid crystal display screens.