Piranha solution (also known as piranha etch) is a powerful cleaning solution made up of hydrogen peroxide and sulfuric acid. It is used to remove organic residue from most substrates. It is an effective oxidizing agent and will hydroxylate most surfaces, making them highly hydrophilic.
5% peroxymonosulfuric acid
To create a 5% peroxymonosulfur acid in the piranha solution, you’ll need to mix a solution of hydrogen peroxide with three parts of concentrated sulfuric acid. Unlike sulfuric acid, which is unstable at high pH, hydrogen peroxide is more stable at low pH. The resulting mixture has a pH of approximately 11.6, which makes it ideal for piranha treatments.
When preparing a piranha solution, be sure to follow all safety instructions. First, the piranha solution is highly flammable, and you should work in a fume hood if possible. The solution should never be heated for more than one hour. Otherwise, the chemicals may decompose quickly and cause a chemical and thermal explosion. In addition, you should avoid adding organics to the solution because they will speed up the decomposition process. In addition, they could potentially irritate the respiratory tract. Lastly, make sure to let the solution cool before using it.
Hydrogen peroxide
Hydrogen peroxide in Piranha solutions is a powerful oxidant that can be dangerous for your health if not handled correctly. The reaction of hydrogen peroxide with oxygen creates an exothermic reaction that destroys organic materials. In addition to attacking organic materials, hydrogen peroxide dissolves metal carbonates and oxides. It is also highly acidic, so be careful when adding this compound to your solution.
When using hydrogen peroxide in Piranha solutions, read and follow all instructions. Always store the solution in a glass container and label it appropriately.
Concentrated sulfuric acid
Concentrated sulfuric acid for piranhas is a mixture of hydrogen peroxide and sulfuric acid. When mixed, the resulting solution is exothermic and will splash out of the container. As the concentration of peroxide increases, the solution may boil and emit a flammable gas. After application, rinse the skin with deionized water.
To make the piranha solution, combine the sulfuric acid and hydrogen peroxide in a graduated cylinder. This is important because the acid will release large amounts of heat during mixing. When mixing, make sure that you stir the solution constantly to avoid splashing. Remember to keep the concentration of sulfuric acid and hydrogen peroxide low to prevent explosions. The reaction between concentrated sulfuric acid and hydrogen peroxide is highly exothermic, which means it will increase the temperature of the water and cause violent boiling.
Hazards
The use of piranha solution, which is a powerful acid, must be supervised by qualified personnel. All laboratory personnel must be trained in proper working conditions and emergency procedures. They must also be provided with the appropriate SOP. The SOP must include information about the hazards of the piranha solution, including its sources, hazards, and protective measures.
A small amount of Piranha solution spilled can be neutralized by using sodium bicarbonate. Then, it should be soaked up using an inorganic-base absorbent. Do not use paper towels or rags to clean up the spill; a mixture of these materials can spontaneously ignite. The waste must be disposed of in a closed waste container.
Storage
When storing the Piranha solution, you must follow the appropriate storage guidelines. The solution should be stored in an open container and not sealed. The air produced from self-decomposition and the oxidation products of organic compounds may cause the container to rupture. Mixing hot piranha with other organic compounds, such as acetone or photoresist, is also dangerous as they can produce an explosion.
You should use a container with a vented cap or a safety valve to prevent pressure buildup. The container should also be labeled as “Acid Piranha Solution – Corrosive, Oxidizer, Toxic.” It must also list the components of the solution.
Proper handling
When working with Piranha, several steps should be followed. The first step is always to wear safety gloves. Make sure to wash your hands thoroughly and put them in a plastic bag before storing them. Never handle Piranha alone. Always have at least one other person with you and ensure they are within sight and hearing distance.
The next step is to prepare the solution. The piranha solution is a mixture of sulfuric acid and hydrogen peroxide. It is flammable and must be handled with extreme caution. You should wear safety glasses and a face shield. You should also wear a lab coat and gloves. As the solution is highly acidic, it will melt plastics. It is advisable to use a fume hood when working with piranha solutions.
