Key attributes
Chemical formula: C₂H₂O₄·2H₂O
CAS: 6153-56-6
Purity: 99.6%
Production standard
COA need meets GB/T1626-2008:
| No. | Items for detecting and analyzing | Standard value |
| 1 | Oxalic acid content (C2H2O4)％≥ | 99.6 |
| 2 | Sulfide (as SO4) ％≤ | 0.07 |
| 3 | Combustion residue ％≤ | 0.01 |
| 4 | heavy metal (as Pb) ％≤ | 0.0005 |
| 5 | Fluoride (as Fe) ％≤ | 0.0005 |
| 6 | Chlorine (as Cl) ％≤ | 0.0005 |
| 7 | Calcium (as Ca) ％≤ | 0.0005 |
| 8 | Water insoluble content ％≤ | 0.02 |
References: Riel Chemical Lab1&2, National public service platform for standards information.
Introduction
Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula
HO−C(=O)−C(=O)−OH, also written as (COOH)2 or (CO2H)2 or H2C2O4.
It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water.
Its name is derived from early investigators who isolated oxalic acid from flowering plants of the genus Oxalis,
commonly known as wood-sorrels. It occurs naturally in many foods.
Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.
Physicochemical property
| Molecular weight: 126.07 g/mol | Appearance: white transparent crystal or powder, industrial products may be slightly yellow due to impurities. |
| Odor: Tasteless or slightly sour. | Density: 1.65 g/cm³ (20°C). |
| Melting point: The dihydrate lost its crystalline water at 101-102°C and was converted to anhydrous oxalic acid (H₂C₂O₄). Anhydrous oxalic acid sublimates at about 189.5°C and decomposes at high temperatures. |
| Solubility: Water: soluble in cold water (about 10 g/100 mL, 20°C), hot water solubility is higher. Ethanol: slightly soluble (approx. 5.7g /100 mL, 20°C) |
| Acid: Binaric acid, acidic stronger than acetic acid (pKa₁=1.25, pKa₂=4.14); It can react with bases, metal oxides, carbonates to form salts (such as sodium oxalate, calcium oxalate). |
| Reducibility: Under acidic conditions can be oxidized by strong oxidants (such as potassium permanganate) to produce CO₂ and H₂O |
| Complexation: Oxalate (C₂O₄²⁻) forms a soluble complex with metal ions (e.g. Fe³+, Al³+). It is used in metal cleaning or rust removal. |
| Thermal decomposition: Decomposition when heated above 150°C, producing CO, CO₂ and H₂O: |
Our manufacturing process
Oxalic acid is produced primarily by oxidizing carbohydrates or glucose with nitric acid or air in the presence of vanadium pentoxide.
Another method is to regenerate nitric acid using oxygen, using a variety of precursors, including glycolic acid and glycol.
As of 2011, only the Japanese company Mitsubishi has used this process.
A newer method requires oxidative carbonylation of alcohols to obtain dioxalate:
4 ROH + 4 CO + O 2 → 2 (CO 2 R) 2 + 2 H 2 O
These diesters are then hydrolyzed to oxalic acid. About 120,000 tons are produced annually.
Historically, oxalic acid was prepared by applying a caustic base (such as sodium hydroxide or potassium hydroxide)
to sawdust and then acidifying the oxalate with an inorganic acid (such as sulfuric acid).
Oxalic acid can also be formed by heating sodium formate in the presence of an alkaline catalyst.
Application
The main uses of oxalic acid include cleaning or bleaching, especially for rust removal (iron complexing agent).
Its use in rust remover is due to the fact that it forms a stable water-soluble salt with trivalent iron, namely the iron oxalate ion.
Oxalic acid is an ingredient in some teeth whitening products. About 25% of oxalic acid is used as a mordant in the dyeing process.
It is also used in bleach, especially for pulping wood, cork, straw, rattan, feathers, as well as for rust removal
and other cleaning, for baking powder, and as a third reagent in silica analysis instruments.
Is oxalic acid cleaning corrosive
1.The corrosion differences of oxalic acid on different materials
Concrete/Cement
Oxalic acid can react with calcium compounds in cement, causing the surface to powderize. Long-term use may weaken the structural strength.
Applicable scenarios: Only for short-term cleaning of cement stains (such as residues from decoration), thorough rinsing is required.
Plastic/Rubber
It has relatively low corrosiveness to most plastics (such as PP and PE), but may cause some rubbers to age (such as sealing rings).
Wood
It will damage the wood fibers, causing color fading or rough surface. It is not recommended for cleaning wooden floors or furniture.
2. Hidden risks of oxalic acid corrosion
Residual corrosion
Even if the surface is thoroughly rinsed, oxalic acid may seep into porous materials such as tile gaps and concrete, causing a prolonged and slow reaction.
Suggestion: Rinse with clean water several times after use and neutralize with an alkaline solution (such as soapy water).
Electrochemical corrosion
In a humid environment, oxalic acid may accelerate the electrochemical corrosion of metals (for example, iron nails rust more quickly).
3. Special Industry Applications and Risks
Electroplating industry
Oxalic acid is used for polishing metals, but a concentration that is too high can cause over-etching of the workpiece (it must be strictly controlled within 5%-10%).
Textile industry
When used as a mordant, excessive use will reduce the strength of the fibers and it needs to be combined with a pH regulator.
Post-processing of 3D printing
A few processes clean resin models with oxalic acid, but it may cause cracking (tolerance needs to be tested).
4. Regulations and Environmental Impacts
Disposal:
Oxalic acid solution should be neutralized to a pH of 6-9 before being discharged and must not be directly poured into the sewer (in some areas, it is classified as hazardous waste).
Transportation restrictions:
High-concentration oxalic acid (>10%) transportation requires a corrosive label, and some countries require special licenses.
FAQ
1.What is your payment term?
We can accept T/T and L/C at sight as payment term.
2.Are you able to deliver on time?
Of course! we specialised in this line for many years,
many customer make a deal with me because we can deliver the goods on time and keep the goods top quality!
3.Do you provide free sample?
Yes, we can provide free sample . You only need to take the express fee.
4.How about the price?Can you make it cheaper?
We always take the customer’s benefit as the top priority.
Price is negotiable under different conditions, we are assuring you to get the most competitive price.
5.Can I visit your company and factory in China?
Sure. You are very welcomed to visit our company in Weifang, China.
(We will have someone responsible for picking up and dropping off at Weifang Airport)
6.What if there is a quality problem?
We have a professional and perfect after-sales service team, timely for you to deal with all problems.
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