Sodium percarbonate (SPC), commonly known as oxygen bleach, is a white, crystalline solid. Chemically, it is a stable, solid adduct of hydrogen peroxide and sodium carbonate (washing soda or soda ash). SPC is used primarily as an effective, environmentally conscious stain remover and laundry booster. When dissolved in water, SPC breaks down, releasing oxygen that provides powerful, color-safe bleaching action, similar to commercial products like OxiClean. This solid form allows for safer handling and storage of the highly reactive hydrogen peroxide.
Required Chemical Precursors
The synthesis of sodium percarbonate requires two specific chemical inputs: sodium carbonate and a highly concentrated solution of hydrogen peroxide. Sodium carbonate, the alkaline component, is commonly sold as washing soda or soda ash and acts as the stabilizing matrix.
Hydrogen peroxide must be used at a high concentration, typically ranging between 50% and 70% by weight, for effective synthesis. This concentration is significantly greater than the common 3% solution found in pharmacies, which is insufficient for a successful reaction. Handling concentrated hydrogen peroxide requires special sourcing and extreme caution due to its powerful oxidizing properties. The final product structure signifies a molar ratio of two sodium carbonate molecules to three hydrogen peroxide molecules.
Detailed Synthesis Procedure
The most efficient method for producing sodium percarbonate involves a “dry process” where concentrated hydrogen peroxide is applied directly to dry sodium carbonate powder.
Mixing and Reaction Control
First, ensure the sodium carbonate is in a fine, anhydrous powder form to maximize surface area. The powder is placed into a specialized mixer, such as a double-cone or fluidized bed reactor, to ensure continuous agitation. The concentrated hydrogen peroxide solution (50% to 70% by weight) is then slowly sprayed onto the agitated powder. The optimal molar ratio is 1.5 moles of hydrogen peroxide for every 1 mole of sodium carbonate.
The reaction forming the perhydrate structure is exothermic, releasing heat. This heat must be managed carefully to prevent premature hydrogen peroxide decomposition, which would drastically reduce the yield. To control the temperature (ideally 20°C to 40°C), the vessel is often cooled, and a continuous flow of air is introduced. This airflow evaporates excess moisture and prevents the mixture from becoming a slurry.
Product Drying
As the reaction proceeds, hydrogen peroxide molecules are incorporated into the sodium carbonate crystal lattice, forming the crystalline adduct. Once liquid addition is complete, the resulting damp powder must be dried further to achieve stability. The product is transferred to a fluidized bed dryer, exposed to controlled hot air to reduce moisture content to less than 1%. This yields the stable, free-flowing granular product.
Safety Protocols and Product Storage
Handling precursor chemicals requires strict adherence to safety protocols, particularly due to the high concentration of hydrogen peroxide used. Concentrated hydrogen peroxide is a powerful oxidizer that can cause severe skin burns, eye damage, and spontaneous combustion if it contacts organic materials. The synthesis must be performed in a well-ventilated area to manage released peroxide vapor or oxygen gas.
Personal protective equipment (PPE) must include:
- Chemical-resistant rubber gloves.
- A lab coat or protective clothing.
- Safety goggles or a face shield to guard against splashes.
The finished sodium percarbonate product must be stored in a cool, dry, and dark environment, away from heat or light. Contact with moisture or heat initiates the decomposition reaction, releasing oxygen and potentially causing pressure buildup in a sealed container.
Never mix synthesized SPC with other common household cleaning agents. When dissolved, SPC releases hydrogen peroxide, which reacts violently with chlorine bleach (sodium hypochlorite) to produce oxygen gas and toxic fumes, such as chloramine. Mixing SPC with acidic substances like vinegar causes a vigorous, bubbling reaction as the carbonate component produces carbon dioxide gas.