Oxygen Scavengers: Principles

Oxygen scavengers work primarily by consuming oxygen in the environment through chemical reactions to inhibit the oxidation and deterioration of goods. Their core mechanisms can be divided into two categories:

Iron-based oxygen scavengers: These primarily consist of iron powder and undergo a redox reaction with oxygen and water in humid environments. Iron atoms lose electrons to form ferrous ions (Fe²⁺), which further react with oxygen and water to produce ferric hydroxide (Fe(OH)₃) and other products. This process continuously consumes oxygen, reducing the oxygen content in the environment. Typical applications include food packaging, pharmaceutical preservation, and rust prevention for metal products.

Sulfite-based oxygen scavengers: These reduce oxygen to water or other harmless substances through a redox reaction, while being oxidized to sulfates. For example, sodium dithionite (Na₂S₂O₄) decomposes under acidic conditions, releasing active substances that combine with oxygen to form sodium sulfate (Na₂SO₄). These oxygen scavengers are suitable for the long-term storage of liquid products, electronic components, and precision instruments.

Technical Principle: The oxygen removal reaction requires specific conditions, such as temperature, humidity, and pH value. Iron-based oxygen scavengers require an ambient humidity of ≥60%, with the reaction rate increasing as humidity rises. Sulfite-based oxygen scavengers require controlled pH levels in the reaction system to prevent side reactions.

Industry Standard: According to GB/T 30799-2014 "Food-grade Oxygen Desiccant", oxygen scavengers must reduce the oxygen content in sealed packaging to below 0.5% within 24 hours, and residues must meet food safety standards. Industrial-grade oxygen scavengers must meet ISO 8573-1 requirements for compressed air quality to prevent pipeline corrosion.

Precautions: Avoid mixing with strong oxidants to prevent runaway reactions; store in a dry environment to prevent premature deterioration; periodically test remaining oxygen removal capacity to ensure effective protection.