What is ferric chloride used for?

Mainly as a coagulant in drinking water and wastewater treatment, removing suspended solids, phosphorus and turbidity, and conditioning sludge. It is also used in etching and metal surface treatment.

Is iron chloride FeCl₂ or FeCl₃?

Both exist. FeCl₃ is ferric chloride, iron in the +3 state, and is the grade used for water treatment coagulation. FeCl₂ is ferrous chloride, +2. Different products, different applications, not interchangeable.

Why use FeCl₃ in water treatment?

It hydrolyses to iron hydroxide flocs that bind fine particles into settleable aggregates, works across a wide pH range, removes phosphorus, and improves sludge dewatering.

What is ferric chloride?

Ferric chloride (FeCl₃, iron(III) chloride) is an iron salt supplied for water treatment as a dark brown liquid at about 40% w/w. Dosed into raw water or wastewater it hydrolyses to iron(III) hydroxide flocs that bind suspended solids, colour and phosphorus so they settle out. Our grade, CHIMIFLOC FR 4014, is listed to NSF/ANSI/CAN 60 (C0237336), the drinking-water treatment chemical standard, and is REACH-registered.

What is the formula of ferric chloride?

Ferric chloride is FeCl₃ — one iron atom in the +3 oxidation state bonded to three chlorine atoms. It is also written as iron(III) chloride. Ferrous chloride is FeCl₂, iron in the +2 state.

What colour is ferric chloride?

Ferric chloride solutions can range from yellow-brown to dark brown. Colour alone does not establish concentration, purity or treatment performance. Check the agreed specification and batch analysis, and refer an unexpected appearance to the supplier before use.

Is ferric chloride soluble in water?

Yes, highly soluble. It dissolves readily and the resulting solution is strongly acidic because FeCl₃ hydrolyses in water.

Does ferric chloride form a precipitate?

FeCl₃ itself dissolves rather than precipitating. What precipitates is iron(III) hydroxide, Fe(OH)₃ — the brown floc formed when FeCl₃ hydrolyses. That precipitate is precisely the mechanism that makes it useful as a coagulant.

Ferric Chloride (FeCl₃)

Ferric chloride (FeCl₃), also called iron(III) chloride, is one of the most widely used coagulants in municipal and industrial water treatment. It is supplied most often as a dark brown aqueous solution, and it works by destabilising the fine suspended particles that will not settle out of water on their own.

This page explains what ferric chloride is, how it behaves in treatment, the grades it is supplied in, and what to consider when buying it. For our own product specification, see CHIMIFLOC FR 4014.

What it is

Ferric chloride is an iron salt in which iron carries a +3 charge. It is distinct from ferrous chloride (FeCl₂), where iron carries a +2 charge — the two are different products with different uses and are not interchangeable. Ferric chloride is strongly acidic in solution and highly soluble in water.

How it works as a coagulant

When ferric chloride is dosed into water, it hydrolyses and forms iron hydroxide. Three things follow:

Charge neutralisation. Most suspended particles carry a negative surface charge that keeps them apart. The positively charged iron species neutralise it so particles can approach each other.
Floc formation. Iron hydroxide precipitates and sweeps fine particles into larger aggregates (flocs) heavy enough to settle or be filtered.
Phosphorus removal. Iron binds phosphate into an insoluble form, removing it from the water.

Ferric chloride works across a relatively wide pH band and is effective in cold water, which is why it is often chosen over alternatives. It consumes alkalinity, so pH correction is a normal part of dosing design.

Where it is used

Drinking water treatment — turbidity, colour and organic-matter removal.
Municipal wastewater — primary treatment, phosphorus removal, sludge conditioning ahead of dewatering.
Industrial effluent — solids and metals removal across food, textile and process industries.
Sludge dewatering — improves the water release of sludge on belt presses and centrifuges.
Industrial etching and metal surface treatment — a separate, non-water-treatment use.

Grades, concentration and supply

When comparing ferric chloride offers, confirm the concentration basis, agreed limits and delivered quantity. Price per litre alone does not establish which offer supplies the required amount of product.

Required application and agreed product specification.
Concentration basis and batch certificate of analysis.
Required documentation and any application-specific approvals.
Quantity, delivery destination, packaging and unloading arrangements.

For CHIMIFLOC FR 4014, compare the product technical sheet with your required specification. Include the application and documentation requirements when requesting a quotation.

Ferric chloride: formula, colour and solubility

What is ferric chloride?: Ferric chloride (FeCl₃, iron(III) chloride) is an iron salt supplied for water treatment as a dark brown liquid at about 40% w/w. Dosed into raw water or wastewater it hydrolyses to iron(III) hydroxide flocs that bind suspended solids, colour and phosphorus so they settle out. Our grade, CHIMIFLOC FR 4014, is listed to NSF/ANSI/CAN 60 (C0237336), the drinking-water treatment chemical standard, and is REACH-registered.
What is the formula of ferric chloride?: Ferric chloride is FeCl₃ — one iron atom in the +3 oxidation state bonded to three chlorine atoms. It is also written as iron(III) chloride. Ferrous chloride is FeCl₂, iron in the +2 state.
What colour is ferric chloride?: Ferric chloride solutions can range from yellow-brown to dark brown. Colour alone does not establish concentration, purity or treatment performance. Check the agreed specification and batch analysis, and refer an unexpected appearance to the supplier before use.
Is ferric chloride soluble in water?: Yes, highly soluble. It dissolves readily and the resulting solution is strongly acidic because FeCl₃ hydrolyses in water.
Does ferric chloride form a precipitate?: FeCl₃ itself dissolves rather than precipitating. What precipitates is iron(III) hydroxide, Fe(OH)₃ — the brown floc formed when FeCl₃ hydrolyses. That precipitate is precisely the mechanism that makes it useful as a coagulant.

Frequently asked questions

What is ferric chloride used for?: Mainly as a coagulant in drinking water and wastewater treatment, removing suspended solids, phosphorus and turbidity, and conditioning sludge. It is also used in etching and metal surface treatment.
Is iron chloride FeCl₂ or FeCl₃?: Both exist. FeCl₃ is ferric chloride, iron in the +3 state, and is the grade used for water treatment coagulation. FeCl₂ is ferrous chloride, +2. Different products, different applications, not interchangeable.
Why use FeCl₃ in water treatment?: It hydrolyses to iron hydroxide flocs that bind fine particles into settleable aggregates, works across a wide pH range, removes phosphorus, and improves sludge dewatering.

Our ferric chloride

Send the application, quantity, destination and required specification with your enquiry. Use the product page to obtain the technical sheet and request safety documentation.

CHIMIFLOC FR 4014 specification

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