Nitric acid is a highly toxic and corrosive acid that has an important role in many industries, such as plastics manufacturing, textile and fertilising industries. "Aqua fortis" and "aqua valens" are additional terminologies for nitric acid, meaning "strong water" and "spirit of fire," respectively. Being such a powerful chemical, nitric acid must be disposed of in a proper manner.
Put on gloves to protect your hands and skin; butyl rubber, neoprene and polythene are the best skin protectors when dealing with acid. Put on a gas mask and wear long clothes and protective goggles. Open all the windows in your bathroom and nearby rooms. Open all doors to create air flow.
Small amounts, under 300 ml, of dilute nitric acid can be disposed of down sinks or toilets as long as there is a large quantity of water used to further dilute the acid. Stop-up your sink using your plug. Pour 4.5 litres of water in the sink. Pour the dilute solution in the water and remove the plug. This same process can be repeated using a toilet. As the acid is draining, continue to further dilute the water with an additional 4.5 litres of filtered water. Do not use mineral water. The minerals in the water could have a violent reaction to the acid.
Concentrated nitric acid or large amounts of dilute nitric acid cannot simply be diluted and poured down the drain. It must first be neutralised with sodium bicarbonate. This chemical process is not safe to perform at home. Go to your local county council website or the UK Environment Agency for advice and contact details for licenced waste disposal companies.
Proper disposal of this material is imperative to safety. Inhalation of nitric acid can cause laboured breathing and coughing. Serious problems include chemical pneumonia; unconsciousness and death have also been reported after nitric-acid inhalation. Contact with skin can cause severe burns. Long-term exposure of nitric acid can erode teeth and permanently damage lungs. This further emphasises the importance of proper disposal.