Chemical Disinfection Products
See text for further discussion of halogens, chlorine dioxide, and silver.
Crystals (Saturated Solution). Because of limited solubility in water, iodine crystals
may be used for disinfection. In one technique for field use, 4 to 8 g of crystalline iodine
is put in a 1- to 2-ounce bottle, which is then filled with water.
A small amount of
elemental iodine goes into solution (no significant iodide is present); the saturated
solution is used to disinfect drinking water. Water can be added to the crystals hundreds
of times before they are completely dissolved.
An alternative technique is to add 8 g of iodine crystals to 100 ml of 95% ethanol.
Increased solubility of iodine in alcohol makes the solution less temperature dependent
and allows much smaller volumes to be used (8 mg/0.1 ml), which can be measured with
a 1-ml syringe or dropper (2 drops).
The stability and simplicity of iodine crystals have led to their testing for in-line
systems that provide continuous water disinfection for remote households and small
communities. In these designs, residual iodine is removed with GAC.
Widely available through suppliers of outdoor products (e.g., Campmor)