Bluish-green monoclinic crystals or granules, odorless. It effloresces in dry air and oxidizes on the surface to brown basic ferric sulfate in moist air. At 56.6°C, it becomes tetrahydrate, and at 65°C, it becomes monohydrate. Soluble in water, almost insoluble in ethanol. Its aqueous solution oxidizes slowly in air when cold and more rapidly when hot. The addition of alkali or exposure to light accelerates its oxidation. Relative density (d15) 1.897. Irritating. Anhydrous ferrous sulfate is a white powder, while the hydrated form is a light green crystal, commonly known as "green vitriol," and its aqueous solution is light green. Ferrous sulfate can be used as a chromatographic analysis reagent, spot analysis for the determination of platinum, selenium, nitrite, and nitrate. It can also serve as a reducing agent, for manufacturing ferrites, water purification, polymerization catalysts, photolithography, etc.
Ferrous sulfate can be used to produce iron salts, iron oxide pigments, mordants, water purifiers, preservatives, disinfectants, etc.;
1. Water Treatment
Ferrous sulfate is used for the flocculation and purification of water, as well as for the removal of phosphates from municipal and industrial wastewater to prevent eutrophication of water bodies.
2. Reducing Agent
Large quantities of ferrous sulfate are used as a reducing agent, primarily to reduce chromates in cement.
3. Medicinal Use
Ferrous sulfate is used to treat iron deficiency anemia; it is also used to fortify foods with iron. Long-term excessive use may cause side effects such as abdominal pain and nausea.
Medically, it can also serve as a local astringent and hematinic, useful for chronic blood loss caused by uterine fibroids.
4. Coloring Agent
a. The production of iron gall ink and other inks requires ferrous sulfate. Mordants for wood staining also contain ferrous sulfate.
b. Ferrous sulfate can be used to dye concrete a yellowish rust color.
c. Woodworkers use ferrous sulfate to give maple wood a silvery hue.
5. Agriculture
It regulates soil pH and promotes chlorophyll formation (also known as iron fertilizer), preventing chlorosis in flowers and trees caused by iron deficiency. It is an essential element for acid-loving plants, especially cycads. In agriculture, it is also used as a pesticide to control wheat smut, apple and梨 scab, and fruit tree canker; it can also be used as a fertilizer to remove moss and lichen from tree trunks.
6. Analytical Chemistry
Ferrous sulfate can be used as a chromatographic analysis reagent.