Acids & Amines

Oxalic Acid Dihydrate

Buy Oxalic Acid Dihydrate in Bulk, Drums & IBCs – Rust Removal, Metal Treatment & Marine Maintenance Applications

Rotterdam Chemicals Group supplies Industrial Grade Oxalic Acid Dihydrate, a widely used organic dicarboxylic acid applied in rust removal, metal surface treatment, wood bleaching and specialty cleaning formulations. Oxalic Acid is valued for its ability to dissolve iron oxides, brighten metallic surfaces and remove mineral staining in controlled industrial environments. We support bulk and packaged supply with structured logistics coordination from our Rotterdam hub.

Acids

What is Oxalic Acid Dihydrate?

Oxalic Acid Dihydrate (CAS No. 6153-56-6) is an organic dicarboxylic acid with the molecular formula C2H2O4·2H2O. The anhydrous form (CAS 144-62-7) has the molecular formula C2H2O4. It appears as a white crystalline solid and is soluble in water. Oxalic Acid functions as both a reducing agent and a chelating agent, particularly effective in dissolving iron oxides (rust). This makes it relevant in metal cleaning, oxide removal and marine maintenance applications where controlled surface treatment is required.

Applications Across Industries

Metal Surface Treatment

Removal of rust, scale and oxide layers from steel and iron components.

Industrial Cleaning

Component in cleaning formulations targeting iron stains and mineral deposits.

Marine Maintenance

Controlled rust removal and brightening of metal fittings and deck hardware.

Wood Processing

Bleaching and stain removal in wood treatment industries.

Textile & Leather Processing

Used in certain dyeing and finishing processes.

Specialty Chemical Manufacturing

Intermediate in chemical synthesis and processing applications.

Grades and Packaging Options

Available Packaging*

200L drums (palletized)

1000L IBC containers

Road tank transportation

Bulk ISO tanks

Custom packaging solutions available upon request

*All formats available directly from our Rotterdam warehouse with international supply support.

Available Grades

Industrial Grade – Designed for rust removal, metal brightening, industrial cleaning and controlled oxide treatment applications.

Specifications and Technical Details

Property

Value

Chemical Name

Oxalic Acid Dihydrate

CAS Number (Dihydrate)

6153-56-6

CAS Number (Anhydrous)

144-62-7

EC Number

205-634-3

HS Code

29171100

Molecular Formula (Dihydrate)

C2H2O4·2H2O

Molecular Weight (Dihydrate)

126.07 g/mol

Physical Form

White crystalline solid

Typical Assay (Industrial Grade)

≥ 99% (industry typical)

Insoluble Matter

≤ 0.01% (typical)

Sulphate

≤ 0.02% (typical)

Iron Content

≤ 50 ppm (industry typical range)

Solubility in Water (20°C)

Soluble

pH (5% solution)

Approx. 1.3 – 1.5

Melting Point (Anhydrous)

Approx. 189–191°C (decomposes)

UN Number

UN 3261

ADR Classification

Class 8 – Corrosive

IMDG Classification

Class 8 – Corrosive

Packing Group

III (solid form, industry typical classification)

Storage Conditions

Store in dry, well-ventilated area, protected from moisture

Stability

Stable under recommended storage conditions

Compliance and Documentation

REACH Registered

Compliant with European transport and safety standards

SDS, TDS, and Certificate of Analysis available upon request

Logistics and Global Supply

Rotterdam Chemicals Group supports bulk, drum and containerised shipments globally. Given its corrosive classification under ADR and IMDG, Oxalic Acid transport is coordinated in accordance with dangerous goods handling requirements. We support structured long-term industrial procurement programs as well as recurring marine sector supply.

Frequently Asked Questions (FAQ)

What is Oxalic Acid Dihydrate primarily used for in industrial and marine environments?

Oxalic Acid Dihydrate is primarily used for rust removal, metal brightening and oxide cleaning in industrial maintenance programs. It is particularly effective at dissolving iron oxide deposits on steel, iron and certain alloys, making it widely used in fabrication workshops, surface preparation processes and corrosion spot treatment. In marine environments, it is commonly applied for controlled rust removal on deck hardware, fittings and metallic components exposed to saltwater conditions. It is also used in wood bleaching, stain removal and selected textile processing operations.

How does Oxalic Acid chemically remove rust and iron stains?

Oxalic Acid reacts with iron oxides to form soluble iron oxalate complexes. This reaction breaks down visible rust layers and allows the oxide material to be rinsed away from the treated surface. Unlike strong mineral acids, Oxalic Acid provides more targeted oxide removal, reducing the risk of excessive base-metal attack when used under controlled conditions.

Is Oxalic Acid classified as dangerous goods for transport and storage?

Yes. Oxalic Acid (solid form) is typically classified under UN 3261 as a corrosive substance (ADR Class 8, Packing Group III). Shipments must comply with dangerous goods packaging, labeling and documentation requirements under ADR and IMDG frameworks.

What safety considerations should industrial users be aware of when handling Oxalic Acid?

Oxalic Acid is corrosive and toxic if ingested or absorbed in significant quantities. Direct skin or eye contact should be avoided, and appropriate personal protective equipment should be used during handling. Adequate ventilation is recommended during industrial use. Detailed hazard identification and recommended protective measures are outlined in the Safety Data Sheet.

Request a Quote or More Information

Looking to secure your supply of Oxalic Acid?

Connect with our sales team to discuss packaging options and international delivery arrangements. Every shipment is supported by complete safety and compliance documentation. Contact us today to review availability and lead times.

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