98% 99% Ferrous chloride tetrahydrate CAS 13478-10-9

What is Ferrous chloride tetrahydrate? How does it work?

Ferrous chloride tetrahydrate is a hydrated form of ferrous chloride. It is a salt of iron and hydrochloric acid and is often used in industrial and laboratory applications. The tetrahydrate form contains four molecules of water of crystallization.

Ferrous chloride tetrahydrate (also ferrous chloride, ferrous dichloride, chemical formula FeCl2·4H2O, CAS 13478-10-9) is the most common commercial form of ferrous chloride, a pale green to blue-green monoclinic crystal. It is a “all-rounder in ferrochemistry” – the source of iron for liquid-phase synthesis of lithium iron phosphate battery cathodes, in wastewater treatment plants for chromate and sulfide removal, as a precursor for iron oxide pigments and as the basis for iron standard solutions and iron complexes in the laboratory. Ferrous chloride tetrahydrate is widely used in many fields such as energy, environmental protection, materials and scientific research, from electric vehicles to wastewater treatment plants, and from pigment workshops to analytical balances.

Basic identification data: Chemical formula FeCl2·4H2O (tetrahydrate, molecular weight 198.81), anhydrous FeCl2 (molecular weight 126.751, CAS 7758-94-3) Tetrahydrate CAS number 13478-10-9, EC number 231-843-4, PubChem CID 24458, UNII S3Y25PHP1W, RTECS number NO5400000, Mineralogical name Rokühnite. Industrial production by reaction of iron with hydrochloric acid (Fe + 2HCl → FeCl2 + H2), and also from recycling of steel pickling waste liquid (hydrochloric acid pickling solution) and titanium smelting by-product.

Physically it is a pale green to blue-green monoclinic crystal (anhydrous form is white to grayish white solid); its density is about 1.93 g/cm3 (tetrahydrate); its melting point is about 105oC (tetrahydrate, decomposes on losing water); it is extremely soluble in water (about 68.5 g/100 mL at 20oC), and its aqueous solution is pale green. It is also soluble in solvents such as ethanol. It is hygroscopic and reducing. It is easily oxidized in air (Fe2+ → Fe3+, solution turns yellow).

Chemically, ferrous chloride tetrahydrate is a reducing agent and oxidizes readily Fe 2+ to Fe 3+. Aqueous solutions are weakly acidic. Reacts with alkalis to form ferrous hydroxide precipitate. Reacts with phosphates, ferrocyanides etc. to form precipitate or coordination compounds. Also forms coordination compounds with ligands such as pyridine, tetrahydrofuran (THF). GHS label elements GHS classification Corrosive to metals (H290) Harmful if swallowed (H302) Skin irritation (H315) May cause an allergic skin reaction (H317) Serious eye damage (H318) Harmful to aquatic life (H412) Keep in a sealed, moisture-proof and light protected container to prevent oxidation and degradation.

From the mechanism of action aspect, the role of ferrous chloride tetrahydrate is irreplaceable by "Fe2+ coordination, precipitation, redox reactions and quantifiability". The mechanisms of action of ferrous chloride tetrahydrate in different applications are as follows:

1.Coordination precipitation mechanism

Fe2+ coordinates with ferrocyanide [Fe(CN)6]4- to precipitate Prussian blue compounds (PBA), whose open framework structure can accommodate the insertion and extraction of sodium ions, making them suitable cathode materials for sodium-ion batteries.

2.Electrochemical redox mechanism

The Fe2+/Fe3+ redox couple possesses a moderate potential and reversible kinetics, therefore, it is not only the energy storage active material of the electrolyte in iron-chromium redox batteries, but also the basis for the charging and discharging of the iron electrode in nickel-iron batteries.

3.Coagulation reduction mechanism

The ferrous salts have two functions in the treatment of water. They reduce hexavalent chromium to trivalent chromium and they react with sulfides to form ferrous sulfide precipitate. Hydrolysis and flocculation remove suspended solids and odors.

4.Oxidation hydrolysis precipitate mechanism

Fe2+ is hydrolyzed under alkaline or oxidizing conditions to produce iron based oxides such as iron oxide (Fe2O3, Fe3O4) which are used as precursors for pigments, magnetic materials and electrode materials.

5. Coordination synthesis and mechanism of iron catalysis

Fe2+ forms iron complexes with ligands such as pyridine, THF and NHC carbene . Iron salts can catalyze CO bond activation and cross-coupling reactions, and are precursors for green iron catalysis systems .

To summarize, ferrous chloride tetrahydrate is a “all-rounder in ferrochemistry”. Thanks to the coordination, precipitation, redox and quantification properties of Fe2+, it is used in a wide range of fields, from lithium iron phosphate to Prussian blue, from wastewater treatment plants to pigment factories, from iron complexes to analytical reagents, from energy to environmental protection, from materials to fine chemicals and scientific research.

What are the uses of Ferrous chloride tetrahydrate?

1. Lithium iron phosphate and iron phosphate cathode materials (source of iron, main application in the manufacture of lithium batteries)

Application areas： Lithium ion power battery, energy storage battery.

Related products: Lithium iron phosphate (LiFePO4) cathode materials, iron phosphate (FePO4) precursors, power battery cathodes, energy storage battery cathodes, two-wheeled vehicle and power tool cathodes, liquid-phase iron sources for cathode material synthesis, etc.

Why it works for this purpose:Fe2+ is co-precipitated with phosphorus and lithium sources in the liquid phase to prepare lithium iron phosphate/iron phosphate precursors with uniform particle size. As a key iron source in the lithium iron phosphate industry chain, the purity of the iron source directly determines the capacity, cycle life and consistency of the cathode material.

2.Iron source for Prussian blue sodium ion battery cathode (field of sodium ion battery)

Application areas： Sodium ion batteries and new energy storage.

Related products: Prussian blue (PB) cathode materials, Prussian white (PW) cathode materials, sodium-ion battery cathodes, energy storage battery cathodes, aqueous sodium-ion battery cathodes, coordination precipitation synthesis of ferrous sources, etc.

Why it works for this purpose: Fe2+ can coordinate with ferrocyanide to precipitate and form Prussian blue-like compounds with an open framework structure, which can reversibly insert and extract sodium ions, therefore it is one of the most used ferrous sources for low-cost sodium-ion battery cathodes.

3.Electrolyte for iron-chromium redox flow batteries (energy storage field in flux)

Application areas：Energy storage for long term, flow batteries.

Related products: Iron chromium flow battery anode electrolyte, FeCl2 electrolyte active material, flow battery energy storage system electrolyte, iron base flow electrolyte, large scale energy storage electrolyte etc.

Why it works for this purpose: The Fe2+/Fe3+ redox couple has a moderate potential and reversible kinetics, allowing it to reversibly transform as a negative electrode electrolyte active material during charge and discharge. Iron and chromium are both cheap and abundant elements, and therefore suitable for large scale long term energy storage.

4. Precursors of oxide electrode materials based on iron (energy storage devices)

Application areas： Electrochemical power storage devices and super-capacitors.

Related products: Iron oxide (Fe2O3) electrode material, magnetite (Fe3O4) electrode material, super capacitor electrode, battery negative electrode active material, iron energy storage electrode precursor, etc.

Why it works for this purpose: Fe2+ can be oxidized and hydrolyzed to prepare high-capacity iron-based oxide electrode materials for supercapacitors and battery negative electrodes with low cost and environmental friendliness.

5. Soft magnetic materials based on ferro and magnetic materials (for motors and power applications)

Application areas：Motors, transformers and power electronics.

Related products： Soft ferrites, iron based soft magnetic powder cores, motor stator and rotor cores, transformer cores, inductor magnetic powder, magnetic materials for electromagnetic devices etc.

Why it works for this purpose: Iron based materials possess high saturation magnetization and good soft magnetic properties. Soft magnetic ferrites and magnetic powder cores can be prepared using iron oxides converted from FeCl2, which supports the efficient operation of power equipment such as motors and transformers.

6.Iron electrode material for nickel-iron battery (alkaline battery field)

Application areas：Alkaline battery,Backup power supply.

Related products:  Nickel iron batteries (Edison batteries) negative electrode iron electrode alkaline battery iron electrode backup power batteries railroad signal power batteries industrial energy storage batteries etc.

Why it works for this purpose: The iron electrode in alkaline electrolyte stores redox energy reversibly via the Fe/Fe(OH)2 redox couple. The iron source for the active material of the iron electrode may be ferrous chloride tetrahydrate. Nickel-iron batteries have long cycle life and are resistant to overcharge and over discharge.

7.Waste water treatment coagulants and flocculants(water treatment field)

Application areas: City sewage treatment and industrial waste water.

Related products:Chromium-containing wastewater treatment agent, sulfide-containing wastewater treatment agent, electroplating wastewater treatment agent, wastewater deodorant, coagulant, phosphorus removal agent, dyeing and printing wastewater treatment agent, etc.

Why it works for this purpose: Double function of reduction and coagulation of ferrous salts, which reduce hexavalent chromium to trivalent chromium, react with sulfides to form ferrous sulfide precipitate, while hydrolyzing and flocculating to remove suspended solids and control the hydrogen sulfide odor in wastewater.

8. Iron oxide pigments and magnetic pigments pre-cursors (pigment industry)

Application areas: Pigment and material industry.

Related products: Pigment iron oxide red (α-Fe2O3), pigment iron yellow, magnetic iron oxide pigment, magnetic pigments for magnetic tapes and cards, pigments for paints, pigments for building materials, colorants based on iron, etc.

Why it works for this purpose: Fe2+ can be prepared by controlled oxidation and hydrolysis to different grades of hematite (iron oxide red) and magnetic iron oxide pigments. These pigments are color stable and have a high hiding power and are used for paints and building materials.

9. Organic synthesis and iron-based catalysts (fine chemicals industry)

Application areas: Synthesis of Organic Materials, Fine Chemical R&D Iron catalysis

Related products: precursors for cross-couplings, CO bond activation catalysis, Grignard reagents coupling catalysis, fine chemical synthesis catalysis, sources of iron for NHC iron catalytic systems, etc.

Why it works for this purpose: Iron salts can catalyze C–O bond activation and cross-coupling reactions. FeCl2, a cheap and green iron catalyst precursor, produces in situ active species and supports high-value-added synthesis of organic compounds.

10. Coordination chemistry and synthesis of iron complexes (scientific research)

Application areas：Organometallic chemistry Coordination chemistry

Related products: Tetrapyridine ferrous chloride, FeCl2(THF)x complexes, NHC iron complexes, iron (II) halide complexes, iron based complex catalysts, iron sources for organometallic synthesis, etc.

Why it works for this purpose:Fe2+ coordinates to a range of ligands such as pyridine, THF and NHC carbene to generate a variety of iron complexes that are often used as starting iron sources in coordination chemistry and organometallic synthesis.

11. Reagents and Iron Standard Solutions for Analytical Chemistry (Analytical Chemistry Field)

Application areas： Analytical Chemistry and Testing.

Related products: Preparation reagents of iron standard solution, Reagents of volumetric analysis, Reagents of spectrophotometric determination, Reagents of water iron content determination, Reagents of metallic material composition analysis, Electrochemical testing electrolyte reagents, etc.

Why it works for this purpose:High purity FeCl2 is of defined composition and traceable purity, enabling preparation of accurate iron standard solutions. It is a stable reagent for determination of iron content and electrochemical research in water quality, environmental protection and metallurgical testing.

12. Teaching and experimental reagents (education area)

Application areas: Teaching of chemistry, experimental teaching.

Related products: Inorganic chemistry teaching reagents, analytical chemistry experiment reagents, iron element property demonstration reagents, precipitation reaction teaching reagents, basic chemistry experiment reagents, etc.

Why it works for this purpose: High purity ferrous chloride tetrahydrate has a well defined composition and typical properties. It is a commonly used reagent in teaching to demonstrate properties of ferrous salts, redox reactions and precipitation reactions.

To summarize, ferrous chloride tetrahydrate (FeCl2·4H2O, CAS 13478-10-9) is a “all-rounder in the chemistry of iron”. By utilizing the coordination, precipitation, redox and quantification properties of Fe2+, it has twelve applications in the fields of iron source for lithium iron phosphate and iron phosphate cathode materials, iron source for Prussian blue sodium-ion batteries, electrolyte for iron-chromium redox flow batteries, precursor for iron-based oxide electrode materials, iron-based soft magnetic materials and magnetic materials, iron electrode materials for nickel-iron batteries, coagulants and flocculants for wastewater treatment, precursors for iron oxide pigments and magnetic pigments, organic chemical synthesis and iron catalysts, iron complexes and coordination chemistry synthesis, analytical chemistry reagents and iron standard solutions, and teaching experimental reagents. Of these, the largest consumption core area of the iron source is lithium iron phosphate cathode materials. Note: This product has reducing and hygroscopic properties, and must be stored in a sealed, moisture-proof, light-protected and oxidation-prevented environment.