What is sulfur dioxide (SO2) gas?

Sulfur dioxide (SO₂) is a colorless, toxic gas with a sharp, irritating odor. Composed of sulfur and oxygen atoms, it is a major air pollutant and a key intermediate in industrial chemistry. SO₂ dissolves readily in water, forming sulfurous acid (H₂SO₃), and is distinct from its liquid or aqueous forms.

What are the key physical properties of SO2 gas?

• State: Colorless gas (liquefies under moderate pressure).

• Odor: Pungent, detectable at concentrations as low as 0.3–1.4 ppm.

• Boiling Point: –10°C (14°F).

• Density: 2.26 times heavier than air.

• Solubility: Highly soluble in water (94 g/L at 20°C).

    Critical Parameters & Concentration:

• Molecular Weight: 64.07 g/mol.

• CAS Number: 7446-09-5.

• Purity: Industrial-grade SO₂ typically exceeds 99.9% for applications like semiconductor manufacturing.

• UN Number: UN1079 (classified as Class 2.3 Toxic Gas and Class 8 Corrosive).

  
  

What are the primary industrial uses of SO₂ gas?

 SO₂ is indispensable across sectors:

• Chemical Manufacturing: Production of sulfuric acid (H₂SO₄), sulfites, and sulfates.

• Food & Beverage: Preservative and bleaching agent for dried fruits, wines, and starch.

• Semiconductors: Precision etching of silicon wafers.

• Pharmaceuticals: Intermediate in drug synthesis and sterilization processes.

• Metallurgy: Ore processing and metal refining.

  
  

How is SO₂ gas transported internationally?

Global transport adheres to strict protocols:

• Packaging: High-strength steel cylinders or ISO tanks with corrosion-resistant linings.

• Regulatory Compliance: Classified under IMDG, IATA, and DOT regulations. Requires hazard labels for toxicity (2.3) and corrosivity (8).

• Safety Measures: Prohibited from mixing with flammables, oxidizers, or food-grade chemicals. Transported in ventilated vehicles, avoiding sunlight and populated areas.

  
  

What are best practices for storing SO₂ gas?

 Safe storage demands:

• Environment: Cool, dry, well-ventilated facilities away from moisture and heat sources.

• Material Compatibility: Use stainless steel or PTFE-lined containers to prevent corrosion.

• Leak Prevention: Install gas detectors, emergency scrubbers, and PPE (acid-resistant gloves, respirators).

What are emerging trends in SO₂ applications?

Growing demand in renewable energy sectors for battery production and flue gas desulfurization (FGD) systems. Innovations in encapsulated SO₂ solutions are reducing handling risks.

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