Explained: Can Hydrogen Peroxide Be Used To Oxidize Aluminum?

Can hydrogen peroxide be used to oxidize aluminum or not? Read our explanation where we have discussed how these two react to each other and their industrial significance.

Hydrogen peroxide, or H₂O₂, has a good reputation of being an oxidizing agent, especially when it comes to metals. It also has quite many uses in the industrial sector due to its oxidizing feature. One such metal that it can oxidize is aluminum, an important industrial metal used in different sectors.

Aluminum is by nature very reactive and starts to react with air even when not physically exposed to other chemicals. It creates an oxide layer when exposed to air, which surrounds itself but protects it from further oxidation. Aluminum can also reduce iron oxides by taking away oxygen from these oxides, a chemical phenomenon commonly used in welding railroad tracks and incendiary bombs (in the past).

Hydrogen peroxide is an oxidizing agent (with +1.77V oxidizing strength) that inherits unsuitability in its molecular nature. It quickly decomposes into water and oxygen gas as shown in the reaction below. This decomposition can be accelerated in the presence of metal catalysts (like transition metals), pH conditions, and light exposure.

2H₂O₂ → 2H₂O + O₂

So, Can hydrogen peroxide be used to oxidize aluminum?

Yes, but there is more to it; here's how: Both hydrogen peroxide and aluminum get along well as the high oxidization power of hydrogen peroxide and the ability of aluminum to be oxidized are brought to each other. The oxidizing agent quickly starts to find any flaw or leftover place to react over the aluminum surface and creates a smooth oxidized layer of aluminum. Their reaction can be stated as:

2Al + 3H₂O₂ → Al₂O₃ + 3H₂O

The above reaction is a classic example of an oxidation reaction where a molecule loses its electrons, which happens with an increase in oxidation state. This happens quite smoothly, which enabled us to use aluminum containers instead of stainless steel to contain hydrogen peroxide liquids, which can create a smooth oxidized layer preventing further oxidation deep down in aluminum. 

This layer perfectly adheres to the underlying bulk metal present beneath the layer and further protects it from most common chemical attacks. A similar chemical phenomenon happens in the above reaction: the aluminum quickly reacts with the hydrogen oxide but is limited by its existing oxide layer formed due to the reaction. The oxidizing agent is quite strong but not strong enough to penetrate this oxidizing layer. Strong acids and bases, mercury, and fluorine can find their way through this layer.

For a continuous reaction between the two, one has to introduce a third chemical that will take away the oxidized layer formed in the solution, and the fresh meat of aluminum will be available for hydrogen peroxide again to oxidize.

In similar cases, hydrogen peroxide is used with other metals to increase the corrosion resistance of such containers. For example, it reacts with chromium oxide layers on stainless steel, which results in improving corrosion resistance.

You will also find hydrogen peroxide in pharmacies at three to six percent concentration, which is commonly used as a disinfectant and is quite effective to kill bacteria, viruses, fungi, and spores. Higher concentrations of more than ten percent can instantly burn your skin!

Such higher concentrations are used in industrial processes for oxidation purposes. For example, it is commonly used in RCA clean processes, where its oxidation comes in handy to remove organic contaminants from silicon wafers.

It is also used during ore processing and for wastewater treatment (Fenton’s reaction), where it is used with iron salts to break down organic pollutants present in the wastewater. Even higher concentrations are used in rocket propulsion and advanced chemical synthesis. Here, the concentrations of this oxidizing agent reach more than ninety percent, where its oxidizing properties are used for the rocket fuel.

Wrapping up:

Both aluminum and hydrogen peroxide are quite a pair when it comes to oxidation. One has a tendency to oxidize and the other to be oxidized, which leads to quick oxidation but with a formation of an oxide layer preventing further oxidation. The oxidation of hydrogen peroxide has many applications, ranging from industrial metal oxidation to electronics, aerospace, corrosion control, and medicine.