Eric Silver
Sessler Group Safety Talk
January 15, 2013

• To remove metal residues (Both)
• To remove noble metals (Aqua regia)
• To remove organic residues (Both)
• To remove carbon residues (Piranha Acid)
• To clean glass fritted filters (Piranha Acid)

• Aqua regia – 1 part conc. HNO
3
+ 3 parts conc. HCl
• Piranha acid – 3 parts conc. H
2
SO
4
(30% or less)
+ 1 part H
2
O
2
• 50% H
2
O
2 or greater can lead to explosions

• Aqua regia – Always add HNO
3
• Piranha acid – Always add H
2
O
2 the H
2
SO
4
SLOWLY TO HCl
SLOWLY TO
• Wear proper PPE – Safety goggles, lab coat and black neoprene gloves
• Prepare solutions in the hood
• Make sure the glassware is completely dry before adding either solution

• Allow the acids to react overnight, due not store hot
• Both are exothermic reactions
• Aqua regia produces NO and Cl
2 gas
• Both solutions are HIGHLY CORROSIVE
• Keep away from solvents and plastics

• Aqua regia – a) Carefully neutralize with
NaHCO
3 and pour down drain or b) Store in properly labeled glass container
• Piranha acid – a) Allow to cool down then carefully neutralize with NaHCO
3 and pour down the drain or b) Store in properly labeled glass container
• Do not dispose with organic solvents