The chemical name of sodium sulfate is anhydrous sodium sulfate, with the molecular formula Na2SO4. It is a white, odorless crystalline powder or colorless orthorhombic crystal, which is easily soluble in water. It belongs to the category of inorganic salt chemical raw materials. In daily life, high-purity anhydrous sodium sulfate is often referred to as sodium sulfate. It is a homologue of sodium sulfate (sodium sulfate decahydrate Na2SO4⋅10H2O) which contains water of crystallization. After dehydration treatment, sodium sulfate can be converted into sodium sulfate.
1. Core chemical properties of sodium sulfate
Sodium sulfate (Glauber’s salt) is chemically stable overall. It does not readily decompose or oxidize under normal temperature and pressure, and it does not react with most weak acids or bases. It exhibits typical chemical characteristics of sulfates and sodium salts:
Solubility: It is readily soluble in water, absorbing a small amount of heat during dissolution. The aqueous solution is neutral. Its solubility shows a clear trend with temperature: low at low temperatures, peaking at around 40℃, and then slightly decreasing with further increases in temperature.
Double displacement reaction: It undergoes double displacement reactions with soluble barium and lead salts, forming insoluble barium sulfate and lead sulfate precipitates. This is a commonly used reaction principle in industrial testing of sodium sulfate purity.
Dehydration and crystallization: It is an anhydrous substance but has some hygroscopic properties. In humid environments, it absorbs moisture to form sodium sulfate (Glauber’s salt). Conversely, sodium sulfate, when heated to above 100℃, loses its water of crystallization and transforms into sodium sulfate.
Thermal stability: It melts at high temperature (about 884℃) and will only decompose in small amounts when calcined at high temperature above 1100℃, releasing gases such as sulfur dioxide. There is no risk of decomposition under normal industrial production and use temperatures.
2. Main sources of sodium sulfate
The sources of sodium sulfate can be divided into two main categories: natural mineral extraction and industrial by-product recovery. Among them, industrial by-product recovery is currently an important source of sodium sulfate for industrial use, while natural extraction mainly produces high-purity sodium sulfate. Both methods can meet the purity and dosage requirements of different industries.
(1) Extraction of natural minerals
Extraction from natural sodium sulfate-containing minerals, salt lake brine, and underground mineral water is the traditional method of sodium sulfate production, mainly divided into two processes:
Salt Lake Brine Evaporation Method: In salt lake producing areas such as Qinghai and Xinjiang in China, natural salt lake brine is used for natural evaporation, concentration, and crystallization under sunlight. First, mirabilite is precipitated, then heated, dehydrated, dried, and pulverized to obtain sodium sulfate. This process is low-cost and suitable for large-scale production.
Mineral Mining Method: Natural mirabilite ore and anhydrous mirabilite ore are mined, then crushed, dissolved, filtered to remove impurities, evaporated, crystallized, dehydrated, and dried to obtain high-purity sodium sulfate. This method is suitable for producing areas rich in mineral resources.
(2) Industrial by-product recycling
Sodium sulfate is recovered from wastewater in industries such as chemical, pharmaceutical, textile, and papermaking. After purification, it is used to produce sodium sulfate (sodium sulfate). This is a resource recycling method that aligns with the needs of green chemical development. Common by-product sources include:
Chemical production by-products: Wastewater containing sodium sulfate is generated during the production of products such as soda ash, caustic soda, and ammonium sulfate. After purification, concentration, crystallization, and dehydration, sodium sulfate is obtained.
Pharmaceutical and fine chemical by-products: Wastewater containing sodium sulfate generated during the production of pharmaceutical intermediates, dyes, and pigments can be treated with specialized purification processes to produce industrial-grade or even food-grade sodium sulfate.
Other industry by-products: Dyeing and bleaching wastewater from textile printing and dyeing, and pulping wastewater from the papermaking industry can have their sodium sulfate recovered after water treatment and refined for use as industrial-grade sodium sulfate.
In addition, the purity of sodium sulfate can be adjusted according to the production process and the degree of purification, from industrial grade (purity above 95%) to food grade and pharmaceutical grade (purity above 99%), to meet the usage requirements of different industries such as textiles, glass, detergents, food additives, and pharmaceutical excipients.
Post time: Feb-25-2026