Pure hydrogen peroxide is inherently reactive and unstable, easily decomposing into water and oxygen. This characteristic not only leads to the loss of its active ingredients but also poses safety risks in closed environments. To address this challenge, activated alumina plays a crucial role as a "guardian."
1. Main Function: Stabilizer
Problem: Pure hydrogen peroxide is highly unstable and prone to decomposition: 2H₂O₂ → 2H₂O + O₂↑
This decomposition reaction can be catalyzed by various factors, such as trace heavy metal ions, light, heat, and alkaline environments.
Decomposition not only reduces the effective concentration of hydrogen peroxide but also generates high-pressure oxygen in a sealed container, posing an explosion risk.
How Activated Alumina Works:
1. Impurity Adsorption: Activated alumina is a porous, highly dispersed solid material with a large surface area and strong adsorption capacity. It acts like a magnet, preferentially adsorbing and locking onto trace heavy metal ions and other suspended particulate impurities in the solution that can catalyze the decomposition of hydrogen peroxide.
2. Catalyst Removal: By removing these decomposition catalysts, the decomposition pathway of hydrogen peroxide molecules is effectively blocked, thereby stabilizing the solution.
3. pH Adjustment: Hydrogen peroxide is more stable under acidic conditions. The surface of activated alumina has a certain acidity, which can help maintain a slightly acidic environment and further inhibit decomposition.
2. Secondary Function: Purification Agent
During the hydrogen peroxide production process (especially the anthraquinone method), trace amounts of organic impurities may be present in the product.
The strong adsorption properties of activated alumina not only adsorb metal ions but also these organic impurities, thereby purifying the hydrogen peroxide solution and producing a higher-purity product.
3. Practical Applications
Industrial Production and Storage: Before hydrogen peroxide leaves the factory, a certain amount of activated alumina (or other stabilizers such as sodium stannate or phosphoric acid) is added as a stabilizer. You'll often see a layer of white particles at the bottom of commercially available industrial-grade or reagent-grade hydrogen peroxide bottles. This is activated alumina, which continues to function during transportation and storage.
