Re: What reactants in carpet cleaners allow them to break down stains?

There are various ingredients found in carpet cleaners that act to clean 
the carpet.  However, the only real reactant would be bleaches and 
enzymes.  Bleaches will oxidize the stain.  Oxidizing will both alter the 
color of the stain and break bonds which allow the other cleaning agents 
to work.  A typical powder formulation would look something like this:

40-50% Sodium bicarbonate (alkaline builder)
10-30% Sodium citrate or Sodium phosphate (sequestering agent)
5-15%  Sodium silicate (rust inhibitor, alkaline builder)
1-5%   Anionic surfactant (surface active agent)
0.1-1% Nonionic surfactant (surface active agent)
0.1-0.5% Fragrance

The formula may also contain: defoamers, dyes, solvent (glycol ethers, 
esters, and alcohols), polymers, bleaches (perborates, percarbonates, 
chlorine bleach), enzymes and preservatives.

A formula like this would be added to water in a ratio of about
1/4-1 oz/gal.

Care should be taken to use ingredients that are non-irritating.  The skin 
can come in contact with the carpet often.  Therefore, it should not 
contain any dangerous ingredients.  Extra care should be used when 
children and the elderly might be exposed.  Many pets can be irritated by 
these chemicals, especially birds.