Ferric chloride

Ferric chloride (CAS 7705-08-0), also known commercially as iron trichloride, is an inorganic iron salt used in water treatment, metal processing, and chemical synthesis.

Where is Ferric chloride used?

• Water treatment: coagulant-flocculant that precipitates suspended solids and phosphates for effluent clarification
• Water treatment: sludge dewatering.
• Metal processing: etchant that selectively dissolves copper and other metals with controlled precision
• Metal processing: manufacture of printed circuit boards (PCB).
• Metallography: etching of metals and alloys to reveal their microstructure.
• Textile and leather: mordant that fixes dyes and improves colour fastness on natural fibres
• Chemical synthesis: Lewis acid catalyst for Friedel-Crafts reactions and other electrophilic processes
• It functions as a coagulant, etchant, or catalyst depending on the sector.

Formulation notes

• Performance is maintained in cold water temperatures that can hinder alum.
• Effective across a broader pH range than other coagulants.

Typical specification

• Commonly sold as a 40% solution.
• Hexahydrate has CAS number 10025-77-1.
• Crystalline hexahydrate contains only 60% ferric chloride due to water of crystallization.

Regulatory status

• Labelling in accordance with Regulation (EC) No 1272/2008 (CLP Regulation) is required in the EU.
• The anhydrous form is classified under UN Class 8, Packing Group III for transport.

Storage, packaging and handling

• Store separately from strong bases and incompatible materials, in a dry, well-closed container.
• Deliquescent and strongly hygroscopic; able to absorb a large amount of water from the atmosphere.

Frequently asked questions about Ferric chloride

What materials are suitable for handling and storing ferric chloride?

It aggressively corrodes most metals, including stainless steel, so non-metallic containers such as HDPE plastic or glass must be used.

In which printing applications is ferric chloride used?

It is used in the intaglio printing industry for etching plates and cylinders for printing images in photography and artworks.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.