S.H.E initiatives: Peroxides

general safety | product stability and safety | precautions

The peroxide division places great emphasis on environmental upkeep and sustainable development of business and technology. In support of our commitment to the customers and the community, we offer free technical services on hydrogen peroxide applications relating to industrial and municipal wastewater and emission problems. Our environmental management system is ISO-14001 certified. The plant is ISO 9002 and ISO 14001 certified. We are now progressing towards TIS18000 certification.

The peroxide division places great importance on the safety and occupational health of the employees. The division also provides technical support and safety assistance to all its customers. To help instruct the operating personnel, we have prepared a material safety data sheet for hydrogen peroxide, which should be prominently displayed in areas where the chemical is stored, handled and used.

A brief outline of the safety precautions and general guidelines for handling and storage of hydrogen peroxide is given below.

General safety
A basic understanding of the properties of hydrogen peroxide is the first step in safe handling of this chemical. Decomposition, caused by contamination, liberates oxygen and heat. In dilute solutions, the heat evolved is readily absorbed by the water present. In more concentrated solutions, the heat raises the temperature of the solution and accelerates the decomposition rate. Therefore, all handling procedures must be directed towards maintaining the purity of the product.

Hydrogen peroxide itself is not flammable, but on decomposition liberates oxygen, which supports combustion. Using large quantities of water best controls fires caused by hydrogen peroxide.

Hydrogen peroxide is not explosive. However, when it is mixed with organic substances, hazardous compounds can result. Small amounts of materials containing catalysts such as silver, lead, copper, chromium, mercury, and iron oxide can cause immediate decomposition and explosive rupture of the containing vessel if the vessel is not properly vented.

Product stability and safety
Hydrogen peroxide solutions contain hydrogen peroxide, pure water and a small amount of stabiliser. The product is extremely stable under normal conditions, when properly stored. The decomposition rate of hydrogen peroxide increases with contamination, alkalinity, increasing temperatures and contact with certain materials of construction. Stabilisers reduce thermally induced decomposition and counteract catalytic decomposition induced by small amounts of metal ions. However, stabilisers cannot prevent decomposition caused by excessive contamination.

Precautions

1. Contamination
To provide some protection against accidental or minute contamination during shipment, storage or handling, low levels of special stabilisers are added to hydrogen peroxide. However, since no additives will prevent decomposition if excessive contamination occurs, the best practice is to prevent contamination through rigorous care in handling and storage. Potential contamination sources include:

• Heat
• Metals are catalytic to H2O2 decomposition (particularly active are e.g. Fe, Co, Ni, Cu, Zn, Cr, Mn)
• Incompatible chemicals (e.g. alkalis, reducing agents)
• Dust, dirt etc.

Rapid decomposition is exothermic and releases large volumes of oxygen, which can overpressurise the container and/or equipment.

2. Confinement
Hydrogen peroxide must not be confined because an inherent property of H2O2 is slow release of oxygen over time. Recommended routine venting provisions include:

• Breather vents
  
• Pressure relief in piping
  
• Vented valves

Hydrogen peroxide can release upwards of ten times its volume in gas during rapid decomposition. The rate of active oxygen loss in large containers is less than 1 per cent per year at normal ambient temperatures. In small containers, the rate of loss is less than 2 per cent per year. The larger the ratio of the surface area to the volume of the hydrogen peroxide, the greater the rate of oxygen loss.

3. Ignition source
Hydrogen peroxide itself is not combustible, but when exposed to excessive heat, rate of decomposition rises exponentially. Hence it must not be contacted with direct flame directly or indirectly. Recommended storage temperature is below 40 0C to maintain product quality as hydrogen peroxide decomposition rate doubles for every 10 0C increase in temperature.

4. Personal exposure and safety
Rubber gloves and suitable protective clothing should be worn while handling hydrogen peroxide. Concentrated solutions have an irritating effect on the skin, mucous membranes and eyes, and should be washed off immediately with copious quantities of water.

Safety goggles should always be worn while handling hydrogen peroxide. Hydrogen peroxide and its decomposition products, oxygen and water are not systemic poisons. However, peroxide vapour can cause irritation and inflammation of the respiratory tract. If inhalation has been prolonged, fresh air should be sought at once and a physician consulted immediately. Clothing must be washed thoroughly with water if it comes in contact hydrogen peroxide; if allowed to dry on the fabric, it may cause fire, particularly if the clothing is soiled.