In order to study the refinery ion-exchange process for colour removal
, some synthetic colourants were passed through a strong base anion ex
change resin. The effect of sodium chloride concentration on their sub
sequent removal from the resin was also studied. Caramels were retaine
d less by the resin than melanoidins or HADP's (hexose alkaline degrad
ation products). Melanoidins were the best removed during salt regener
ation, but only about 50% of the caramels and HADP's were removed. HAD
P's were the major colourants to be fixed irreversibly to the resin.