What is carbon dioxide (CO₂)?

Carbon dioxide (CO₂) is a naturally occurring, colorless, odorless gas composed of one carbon atom and two oxygen atoms. It is a critical component of Earth’s atmosphere (0.03–0.04% by volume) and plays a vital role in processes like photosynthesis and the carbon cycle. Solid CO₂, known as dry ice, is widely used for refrigeration and industrial applications.

What are the physical properties and critical parameters of CO₂?

• State: Colorless gas at standard conditions; liquefies under pressure or cooling.

• Density: 1.977 g/L (1.5 times heavier than air).

• Melting Point: –56.6°C; Sublimation Point: –78.5°C (dry ice).

• Solubility: 1:1 volume ratio in water at 20°C, forming weak carbonic acid.

Key Parameters:

• Molecular Weight: 44.01 g/mol.

• CAS Number: 124-38-9; UN Number: UN2187 (Class 2.2 Non-Flammable Gas).

• Purity: Industrial grades range from 99.9% for food preservation to 99.999% for semiconductor manufacturing.

  
  

What are the primary industrial uses of CO₂?

CO₂’s versatility spans diverse sectors:

1. Food & Beverage: Preserves perishables via dry ice refrigeration and carbonates drinks.

2. Welding: Acts as a shielding gas to prevent oxidation in metal fabrication.

3. Fire Suppression: Extinguishes flames by displacing oxygen, ideal for electrical fires.

4. Semiconductors: High-purity CO₂ aids in silicon wafer cleaning and plasma etching.

5. Healthcare: Used in cryotherapy and laparoscopic surgery for organ visualization.

6. Renewable Energy: Enhances oil recovery (EOR) and serves as a coolant in nuclear reactors.

   
   

How is CO₂ transported internationally?

Global logistics adhere to strict safety protocols:

• Packaging: High-pressure steel cylinders, ISO tanks, or cryogenic containers for liquid CO₂.

• Regulations: Complies with IMDG, IATA, and DOT standards (UN2187). Dry ice shipments require ventilation to prevent CO₂ buildup.

• Safety Measures: Vehicles must avoid heat and carry leak-detection systems. Escorts are mandatory for large-scale transport.

  
  

What are best practices for CO₂ storage?

Safe storage requires:

• Facility Design: Ventilated, temperature-controlled areas away from heat sources. Dry ice must be stored in insulated containers.

• Material Compatibility: Stainless steel or carbon steel tanks; avoid plastics for high-pressure storage.

• Risk Mitigation: Install gas detectors and emergency ventilation to prevent asphyxiation risks in confined spaces.

  
  

What trends are shaping CO₂ applications?

Innovations include:

• Carbon Capture & Storage (CCS): Converting CO₂ into synthetic fuels or sequestering it underground to reduce emissions.

• Sustainable Dry Ice: Recycling programs to minimize waste in food and pharmaceutical logistics.

• Supercritical CO₂: Used as a solvent in eco-friendly manufacturing processes.

  
  

Expert Insight:
Dr. Li Wei, a chemical safety specialist, emphasizes: “CO₂’s dual role as an industrial asset and environmental challenge demands innovative handling. Prioritize leak-proof systems and staff training to balance productivity and safety.

Call to Action:
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