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.
Can oxalic acid clean ores
1.The uses of oxalic acid in cleaning ores
Remove iron oxides
Oxalic acid can react with rust (Fe₂O₃) to form a soluble iron oxalate complex, which is suitable for cleaning ores containing iron (such as hematite and limonite) or those contaminated with iron on the surface.
Dissolve carbonate gangue
For ores containing calcium carbonate (CaCO₃) or magnesium carbonate (MgCO₃), such as calcite and dolomite, oxalic acid can react slowly to form soluble oxalates and carbon dioxide.
Clean quartz or silicate ore
Oxalic acid can assist in removing the residual metal oxides on the surface of silicate ores, improving their purity (such as quartz, feldspar, etc.).
2. Operating Steps (Example)
Prepare the solution
Use a 5% to 10% oxalic acid solution (a concentration that is too high may corrode the ore itself).
Heating to 50-60℃ can enhance the reaction efficiency (a well-ventilated environment is required).
Soak or scrub
Soak the ore in oxalic acid solution for several hours to 24 hours, or directly scrub the stubborn stains on the surface.
Neutralization and rinsing
After processing, thoroughly rinse the ore with clean water. The residual oxalic acid may be harmful to subsequent processing or the environment.
A small amount of sodium bicarbonate (baking soda) solution can be used to neutralize the acidity before rinsing.
3. Precautions
Ore type restrictions
Applicable: Iron oxides, carbonate impurities.
Not applicable: Sulfide ores (such as pyrite), certain rare earth minerals (which may form insoluble salts with oxalic acid).
Safety protection
Oxalic acid is corrosive. Gloves, goggles and a gas mask should be worn (especially when heated).
Operate in a well-ventilated environment and avoid inhaling vapors.
Environmental protection treatment
The waste liquid contains heavy metals or oxalates and should be treated as hazardous waste and must not be discharged directly.
Alternative solution
If oxalic acid has limited effect, you can try other acids (such as hydrochloric acid, citric acid) or physical methods (ultrasonic cleaning).
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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Industrial Grade Dihydrate Oxalic Acid Crystal CAS NO 6153 56 6 For Chemical Raw Materials Images
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