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Schools in Science


Unwanted or waste chemicals and research samples should be destroyed chemically if possible and within the laboratory of generation. Otherwise properly labeled waste should be taken to the Faculty Store at the appropriate time for disposal through EPA licensed contractors such as Chemsal.

Information on destruction of wastes

If you are carrying out a disposal for the first time, ensure that your supervisor or an experienced researcher is available to assist you.Adequate safety equipment such as fire extinguishers, breathing apparatus etc. should be on hand as determined by your Risk Assessment.

Disposal of sodium residues

Several fires have occurred in this School during destruction of sodium residues from drying solvents. These could have been avoided by strict use of the following procedure:
  • The flask or Winchester should be securely clamped behind a safety screen in an empty fume cupboard.
  • The sodium wire residues should be well covered with isopropanol and left for at least 2 hours, and preferably overnight.
  • Sodium oxide / hydroxide encrustations are very soluble in water but insoluble in alcohols and there may be unreacted sodium underneath.
  • The solution should be carefully poured into a large volume of water in a beaker or bucket, NOT down the drain. Water should not be added to the container until it has been thoroughly rinsed with ethanol and inspected visually for signs of undissolved material.

Disposal of used solvents

Used solvents should be recovered for use if possible. All solvents MUST be properly labelled with the name and the relevant Dangerous Goods diamond affixed. Where this is not practicable, they may be stored in Winchesters, in the appropriate cabinet and taken to the store when full for disposal by Chemsal.

Waste solvents should be separated under the following categories:

  • All chlorinated hydrocarbons (Class 6.1 (pdf 100kb))
  • Flammable solvents which are not water-soluble (e.g. Hexane - Class 3 (pdf 100kb))
  • Carbon disulfide and other special cases must be stored separately and properly labelled.

In some cases where small quantities only of water-soluble solvents are used for washing, these may be flushed down the drain along with a vigorous flow of water. The generation and storage of any potentially explosive mixtures, e.g. acetone and chloroform, is NOT permitted.