Гидрат сульфата железа

Description

Ferrous sulfate hydrate (iron(III) sulfate hydrate, Fe2(SO4)3 xH2O) is the hydrate form of iron(III) sulfate. Gray-white granular product.

Basic Attributes

• CAS No: 15244-10-7 (also CAS 934963-31-2)
• Chemical formula: Fe,3/2H2O4S,xH2O
• Molecular weight: 417.89; exact weight 417.73600
• EU number: 233-072-9
• PSA specifications: 267; XLogP3: -0.84090

Physico-chemical characteristics

• Appearance: grey-white, granular
• Density: 3.097 g/cm3
• Melting point: 480°C (with decomposition)
• Boiling point: 330 °C at 760 mm Hg. Art.
• Solubility: soluble in water, slightly soluble in alcohol

Storage conditions

Store at room temperature.

Safety Information

• Transport codes: UN 3077
• WGK Germany: 3
• Hazard class code: 22-36/37-41-38
• Safety instructions: 26-39
• RTECS number: NO8520000
• Tags: Xn
• Precautions: P280, P305+P351+P338; according to aggregated GHS data also P264, P270, P301+P312, P302+P352, P310, P321, P330, P332+P313, P362, P501
• Hazard Statements: H302 (90.7%), H315, H318
• Aggregated GHS information provided by 43 companies from 2 notifications to the ECHA C&L register

Scope of application

Iron(III) sulfate hydrate is used as a coagulant in the preparation of drinking water and the treatment of industrial and domestic wastewater, as a raw material for the production of iron oxide pigments, as a mordant in textile dyeing and as an etching reagent in metalworking and electronics.

Mechanism of action

When dissolved, the salt hydrolyzes to form positively charged ferric hydroxo complexes, which neutralize the charge of suspended water particles and bind them into flakes that settle or are filtered during water treatment - the same principle as other coagulants based on iron(III) and aluminum(III).

Transportation conditions

Transport in a closed moisture-resistant container according to UN number 3077, observing the requirements of the hazard class code 22-36/37-41-38.

Hydrated and anhydrous forms

On the market of coagulants based on ferric iron, both the hydrated form of iron(III) sulfate and the anhydrous salt are found. The hydrate usually dissolves more easily and quickly when preparing a working solution at the site of use, while the anhydrous form is more compact in volume with the same mass of active substance, which is more advantageous when transporting over long distances. The choice of a specific form is determined by the logistics and equipment of the water treatment station - the containers of the solution units, the mixing speed and the required concentration of the dosed solution.

Dosage recalculation

The content of active iron per unit mass of the commercial product in the hydrate is lower than that of anhydrous salt, due to the proportion of water of crystallization in the composition. When switching from one form to another, the dosage at the water treatment station is recalculated precisely on the content of active iron, and not on the mass of the purchased reagent, otherwise the efficiency of coagulation will deviate from the expected.

Industry role among coagulants

Coagulants based on ferric iron (sulfates, chlorides) work on the same principle as aluminum coagulants (aluminum sulfate, polyaluminum chloride), but form a smaller sediment and work better in cold water and over a wide pH range. The choice between iron and aluminum coagulants is determined by the composition of the source water, the requirements for the residual metal content in the purified water, and the cost of the reagent per volume of water being treated.