Clean up of Mercury spills in the laboratory.
Observations
Do not use a vacuum cleaner to suck up spilled mercury.
- It will contaminate your vacuum.
- Heat from the vacuum will evaporate the mercury and the vapor will be distributed throughout the work area.
Do not use a broom to sweep up mercury.
- The mercury will be broken up into smaller beads and cause spreading as well as contaminate the broom.
- Use a light source such as a flashlight to locate mercury. The light will reflect off the mercury beads and you will be able to see them.
Cleaning up the spill
Small Spills
Use Mercury Spill Kits for small spills.
Large Spills
Precautions
- Keep personel away from spill area.
- Turn off all heaters to minimize vaporizing of mercury.
- Do not touch the mercury with bare hands.
- Remove watch or jewellery from hands, because mercury bonds with metals.
Procedures
Note: Dirty mercury collected from large spills can be kept in a container for cleaning and recovery.
Add a layer of water over the mercury in the container to suppress any mercury vapor.
Clean up procedures depend on the type of surfaces on which the mercury is spilled, namely Hard surface, Carpet or Rug, Drain pipe, or Laboratory sink.
Hard surface
With gloves on, gather up mercury beads together in poodle by using a rigid piece of paper. Suck up the mercury with a dropping pipette and empty into a wide mouth glass jar. Pick up remaining small droplets with sticky paper and put in sealable plastic bag. When finished, put the sticky paper, stiff paper, gloves, and dropping pipette into the plastic bag and label as Mercury waste.
Carpet or rug
Cut out the contaminated area and put in plastic bag together with clean up items and label as Mercury waste
Drain pipe
Mercury will get caught in the sink trap. Remove trap and empty contents into wide mouth container and seal with tape. Label as Mercury waste
Laboratory sink
Mercury will sink to the bottom if there is water in the sink. Remove as much water as possible and recover mercury with dropping pipette. Put in plastic bag and label as Mercury waste
After cleaning up, wash hands thoroughly with soap and water to avoid transfer of any mercury to mouth or eyes.
Mercury waste should not put in the regular waste bay, but kept separate for disposal options and to avoid mercury contamination from spreading.
Commercial Products ¹
There are some commercially available absorbents and kits specifically designed to clean up and manage mercury spills.
Mercury collector
This is a screw-capped cup with foam padded lid and perforated disk on receiver cup. The mercury is picked up by pressing the foam lid against the droplets which is released into the receiver cup when the lid is recapped.
Absorbents
These are specialty chemicals which are spread on the spill. The mercury drops are absorbed and stabilized for easy disposal.
Spill kits
These kits provide everything to clean up and mamage a mercury spill.
A spray to control mercury vapor in the air before clean up.
A liquid vapor suppressant to suppress vapor at its source.
A decontaminant to form stable mercury salts for easy disposal.
These kits include spill pick up tools such as storage container, safety goggles, gloves,resealable plastic bags, mini shovels, scoops, foam pads, Mercury wastelabels and instruction booklet.
Destruction methods
Acid decomposition
Add 1:1 nitric acid slowly to collected mercuryin fume hood in order to decompose the mercury. Add plenty water when the reaction is complete and discard appropriately. Can be washed down with a copious flow of tap water.
Absorbents
These form stable compounds with the mercury and can be suitably disposed.
Recovery methods
Distillation
This is possibly the best clean up process for contaminated mercury. However, boiling mercury and then cleaning up the distillation apparatus is quite hazardous. Some simple methods can be used to clean dirty mercury to satisfy most needs. Double or triple distilled mercury can be purchased in small quantities for special research applications such as polarography.
Wash and dry
Note :Use a fume hood and a large spill tray for all the following methods.
Dip filter paper into mercury and manipulate it around to remove small amounts of dust and debris.
Syringe method
Use a 10 ml syringe with needle. Stick the needle beneath the mercury in the contaminated mercury container and withdraw clean mercury. Hold the syringe and plunger up with both hands when the mercury is sucked up. This action prevents the mercury from spilling back out. Transfer the mercury to the recovery vessel. Continue this process if necessary.
Filter method
Place filter paper into funnel and bore a pin hole in the bottom of the cone.Put the funnel in a collection vessel with funnel stem close to the bottom to minimize splashing. Slowly pour the contaminated mercury into the funnel and allow it to filter through. The dirty sludge will remain on the filter paper. The filterd mercury can be refiltered using neww filter paper. Repeat this process two or three times until the mercury is clean and gives a characteristic bright and shiny appearance.
Reference:
1. Aldrich Chemical Company catalogue
