Iron Sulfates

Iron Sulfates

 

sulfates of divalent and trivalent iron, FeSO4 and Fe2(SO4)3.

The sulfate of divalent iron separates from aqueous solutions at 1.82°–56.8°C as pale green crystals of FeSO4.7H2O, known in industry as green vitriol. The solubility of anhydrous FeSO4 in 100 g of water is as follows: 26.6 g at 20°C and 54.4 g at 56°C. Green vitriol can be made by treating scrap iron or cuttings of roofing iron with dilute sulfuric acid. In industry it is a by-product of the pickling of iron sheets, wire, or other articles with dilute H2SO4 to remove scale. It is used in making ink, in dyeing (to dye wool black), and to preserve wood.

Ferric sulfate forms crystalline hydrates containing various amounts of water—for example, Fe2(SO4)3.9H2O (yellow). It is readily soluble in water. It forms iron alums with sulfates of alkali metals and (NH4)2SO4. It is made industrially by dissolving ferric oxide in 75–80 percent sulfuric acid. It is used in water purification as a coagulant and for making iron alum.

References in periodicals archive ?
This heat is used for the production of the steam and hot water that is needed to dissolve the iron sulfates or wash the pigments.
Team members from NASA's Johnson Space Center in Houston feel initial readings suggest that iron is mostly present in an oxidized form as ferric sulfate and that some of the differences in tints at Troy observed by the panoramic camera may come from differences in the hydration states of iron sulfates.
Also in his stock were colorful (but unfortunately unstable) fine crystals of the iron sulfates voltaite, coquimbite and botryogen.