Procurement Report: Oxalic Acid (Acid Oxalic)

Product Category: Industrial & Laboratory Chemicals (Inorganic Acids) Primary CAS Number: 144-62-7 Chemical Formula: C₂H₂O₄

1. Technical Specifications and Performance Metrics

Oxalic acid is a dicarboxylic acid appearing as a white crystalline solid. Procurement specifications must align with the intended application, ranging from bulk industrial cleaning to high-precision analytical work.

• Physical Properties:
  • Appearance: White crystalline powder or granules.
  • Melting Point: Typically ranges between 189°C and 190°C (decomposes).
  • Molecular Weight: Approximately 90.03 g·mol⁻¹.
  • Solubility: Highly soluble in water; solubility increases significantly with temperature.
• Purity Grades:
  • Technical Grade: Typically 98.0% – 99.0% purity. Suitable for general cleaning and metal treatment.
  • ACS/Reagent Grade: Typically ≥99.5% purity. Required for laboratory titrations and pharmaceutical testing.
  • Pharmaceutical Secondary Standard: Certified Reference Material (CRM) grade with specific impurity limits defined by pharmacopeias.
• Performance Metrics:
  • Chelating Efficiency: High affinity for iron and other heavy metals, making it effective for rust removal.
  • Acidity (pKa): pKa₁ ≈ 1.25; pKa₂ ≈ 4.14.

Actionable Recommendation: When drafting purchase orders, explicitly specify the required purity percentage (e.g., "≥99.5%") and the specific form (anhydrous vs. dihydrate). For applications involving water hardness or metal cleaning, verify the chloride and sulfate impurity limits in the Certificate of Analysis (COA), as these can interfere with downstream processes.

2. Industry Compliance and Quality Assurance

Oxalic acid is subject to varying regulatory frameworks depending on the end-use. Ensuring compliance is critical for avoiding supply chain disruptions and legal liabilities.

• Certification Standards:
  • ACS Certified: Must meet American Chemical Society standards for analytical chemistry, ensuring low levels of heavy metals and non-volatile residues.
  • Pharmaceutical Standards: For pharma applications, the material must serve as a Certified Reference Material (CRM) or Secondary Standard, requiring rigorous documentation for release testing.
  • ISO/Quality Management: Suppliers should ideally hold ISO 9001 certification and provide batch-specific Certificates of Analysis (COAs).
• Safety & Handling:
  • Hazard Classification: Classified as toxic if ingested and corrosive to skin/eyes.
  • Documentation: Mandatory Safety Data Sheets (SDS) compliant with GHS (Globally Harmonized System) must accompany every shipment.
• Sourcing Verification:
  • Buyers must request detailed COAs for every batch to verify purity levels and impurity profiles (e.g., heavy metals, ash content).

Actionable Recommendation: Do not accept generic COAs for critical applications. Require batch-specific documentation that traces the material back to the manufacturing lot. For pharmaceutical or food-grade adjacent uses, verify that the supplier holds specific regulatory approvals (e.g., FDA, EU regulations) relevant to the destination market.

3. Cost Efficiency and Integration Capabilities

Oxalic acid is a commodity chemical with a relatively stable cost structure, though prices fluctuate based on raw material costs (ethylene/glycerol) and logistics.

• Cost Drivers:
  • Purity Premium: ACS/Reagent grade commands a 20% – 40% price premium over Technical grade.
  • Packaging: Bulk bags (25kg) offer the lowest cost per kilogram, while small bottles (500g/1kg) incur higher unit costs due to packaging and handling.
  • Logistics: As a solid, it is generally safer and cheaper to ship than liquid acids, reducing hazardous material transport surcharges.
• Integration Capabilities:
  • Compatibility: Easily integrated into existing water treatment, metal pickling, and cleaning systems.
  • Storage: Requires dry, cool storage to prevent caking (hygroscopic nature). Compatible with standard polyethylene or lined steel containers.
• MOQ and Lead Time (Typical B2B Ranges):
  • Minimum Order Quantity (MOQ): Typically 25 kg for bulk, 1 kg for lab samples.
  • Lead Time: 2 – 4 weeks for standard international shipping; 1 – 3 days for domestic regional stock.

Actionable Recommendation: Optimize costs by consolidating orders to meet bulk MOQs (e.g., 1,000 kg pallets) rather than ordering small increments. For high-volume users, negotiate long-term contracts to lock in pricing against raw material volatility. Ensure warehouse infrastructure includes dehumidification to maintain product integrity and prevent clumping.

4. Typical Use Cases

Oxalic acid is versatile across multiple industries due to its strong chelating and reducing properties.

• Metal Treatment & Pickling:
  • Application: Removal of rust, scale, and oxide layers from steel, aluminum, and copper surfaces.
  • Mechanism: Forms soluble complexes with iron oxides.
• Water Treatment:
  • Application: Scale removal in boilers and cooling towers; sequestering iron and manganese in drinking water.
• Laboratory & Analytical Chemistry:
  • Application: Standardizing permanganate solutions, precipitation of calcium, and as a reducing agent in titrations.
• Pharmaceutical & Research:
  • Application: Use as a secondary standard for assay calibration and in the synthesis of specific organic intermediates.
• Cleaning & Maintenance:
  • Application: Household and industrial cleaning agents for removing mineral deposits, ink stains, and rust on concrete or masonry.

Actionable Recommendation: Match the grade strictly to the use case. Do not use Technical grade in analytical titrations due to potential impurity interference. For water treatment, ensure the concentration is calculated based on the specific hardness of the water source to avoid over-dosing.

5. Long-Term Planning Considerations

Strategic procurement of oxalic acid requires monitoring market trends and regulatory shifts.

• Market Trends & Demand Signals:
  • Green Chemistry: Increasing demand for non-toxic alternatives in cleaning is driving steady growth, though oxalic acid remains a benchmark for rust removal.
  • Battery Industry: Emerging applications in lithium-ion battery recycling and cathode material processing may create new demand streams.
  • Supply Chain Resilience: Global supply chains for organic acids are becoming more regionalized to mitigate logistics risks.
• Regulatory Outlook:
  • Stricter environmental regulations regarding heavy metal discharge in industrial effluents may increase the need for high-purity oxalic acid to ensure complete chelation and safe disposal.
• Sustainability:
  • Suppliers are increasingly expected to provide data on carbon footprint and sustainable sourcing of raw materials.

Actionable Recommendation: Develop a dual-sourcing strategy to mitigate supply chain risks. Monitor the battery recycling sector for potential new application volumes. Incorporate sustainability criteria into supplier evaluations, requesting data on manufacturing emissions and waste management practices.

6. Special Product Recommendations

Selecting the right product variant is crucial for balancing cost, performance, and risk.

| Product Type | Best-Fit Buyer | Key Specs | Risk Check | Procurement Advice | | :--- | :--- | :--- | :--- :--- | | ACS Certified Grade | Laboratories, R&D, Pharma QA | Purity ≥99.5%, Low Heavy Metals | High risk of counterfeits if not from authorized distributors | Verify COA against ACS monograph; request batch traceability. | | Technical Grade (Bulk) | Industrial Cleaning, Water Treatment | Purity 98.0%–99.0%, 25kg Bags | Variable impurity levels affecting efficiency | Test a sample batch for chloride/sulfate content before full rollout. | | Pharma Secondary Standard | Pharmaceutical Manufacturers | CRM Certified, Specific Impurity Limits | Regulatory non-compliance if documentation is missing | Ensure supplier is an authorized CRM provider; check expiration dates. | | Dihydrate Form | General Cleaning, Educational | C₂H₂O₄·2H₂O, Stable Crystals | Lower active acid content per weight vs. anhydrous | Calculate dosage based on water content (approx. 30% water). | | Anhydrous Form | High-Temp Processes, Synthesis | C₂H₂O₄, Low Moisture | Hygroscopic; requires dry storage | Use immediately after opening or store in desiccated environment. |

Actionable Recommendation: For routine industrial cleaning, Technical Grade is the most cost-effective choice. However, for any application involving human health (pharma/food) or precise measurement (lab), the premium for ACS or CRM grades is non-negotiable. Always verify the "Dihydrate" vs. "Anhydrous" status, as this impacts the molar calculations for dosing.

7. Frequently Asked Questions (FAQ)

1. What is the difference between Oxalic Acid Anhydrous and Dihydrate? The dihydrate form (C₂H₂O₄·2H₂O) contains two water molecules per acid molecule, making it lighter in terms of active acid content per kilogram compared to the anhydrous form. The dihydrate is more stable and common for general use, while the anhydrous form is used where water introduction must be minimized.

2. Is Oxalic Acid safe for use in food processing? It is generally not approved for direct food contact in many jurisdictions due to toxicity. However, it is used in specific industrial cleaning processes for food equipment, provided it is thoroughly rinsed and residues are below strict regulatory limits. Always check local FDA or EFSA regulations.

3. How should Oxalic Acid be stored to maintain quality? Store in a cool, dry, well-ventilated area in tightly closed containers. It is hygroscopic and can absorb moisture from the air, leading to caking or deliquescence. Avoid storage near strong oxidizers or bases.

4. What is the typical shelf life of Oxalic Acid? When stored correctly in sealed containers, Oxalic Acid has a long shelf life, typically 2 to 5 years. However, ACS and Pharma grades have specific expiration dates based on stability testing.

5. Can Oxalic Acid be used to remove rust from stainless steel? Yes, it is effective for removing rust from stainless steel. However, it should be used with caution and neutralized immediately after cleaning to prevent potential pitting or corrosion if left on the surface for extended periods.

6. What are the primary safety hazards associated with Oxalic Acid? It is toxic if swallowed and can cause severe irritation to the eyes, skin, and respiratory tract. Long-term exposure can lead to kidney damage (nephrotoxicity) due to calcium oxalate crystal formation. Proper PPE (gloves, goggles, respirator) is mandatory.

7. How do I verify the purity of a bulk shipment? Request a batch-specific Certificate of Analysis (COA) from the supplier. The COA should list the assay percentage and impurity limits (e.g., heavy metals, ash). For critical applications, consider sending a sample to an independent third-party laboratory for verification.

8. Is Oxalic Acid biodegradable? Yes, oxalic acid is naturally biodegradable and occurs in many plants. However, high concentrations in wastewater can be toxic to aquatic life and should be treated according to local environmental discharge standards.