Oxygen absorbents are chemical substances that can effectively remove oxygen from enclosed environments, and are widely used in food preservation, pharmaceutical storage, electronic component protection, and cultural relic preservation. Their core principle is to convert oxygen in the environment into stable compounds through chemical reactions, thereby reducing the oxygen concentration and delaying oxidation reactions.
Currently, mainstream oxygen absorbent methods are based on chemical systems such as iron-based, sulfite, and ascorbic acid. Among these, iron-based oxygen absorbents are the most common and cost-effective choice. Their working principle involves iron powder reacting with oxygen in a humid environment to form rust (Fe₂O₃·nH₂O), thus consuming oxygen. The advantages of this method are high reaction efficiency and low cost, but it requires certain humidity conditions and may produce solid residues after the reaction. To optimize performance, modern iron-based absorbents often add auxiliary components such as sodium chloride and activated carbon to improve the reaction rate and oxygen absorption capacity.
Sulfite-based oxygen absorbers react with oxygen via sodium sulfite (Na₂SO₃) or sodium metabisulfite (Na₂S₂O₅) to form sulfates. This method is suitable for environments sensitive to metal corrosion, but the reaction products may affect the stability of some products. Ascorbic acid (vitamin C) systems utilize their reducing properties to react directly with oxygen, making them suitable for food packaging, especially in environments with strict requirements for chemical residues.
In terms of application technology, the encapsulation method of oxygen absorbers is crucial. Typically, a breathable but waterproof film material (such as polyethylene or polypropylene) is used to encapsulate the absorber, ensuring oxygen can enter while moisture and reaction products do not leak. Furthermore, some high-end products use multi-layer composite materials to precisely control the oxygen absorption rate and extend the protection cycle.
In recent years, researchers have also developed novel oxygen absorption technologies based on enzyme catalysis or photocatalysis, such as the glucose oxidase system, which can efficiently remove oxygen under mild conditions, but its high cost has limited its widespread application. In the future, with advancements in materials science, oxygen absorbers will develop towards higher efficiency, environmental friendliness, and controllability to meet broader industrial and civilian needs.
