| Abstract: | A series of chemically modified celluloses with different functional groups present in various extents were prepared by separately oxidizing cotton cellulose by potassium metaperiodate, potassium dichromate–sulfuric acid, potassium dichromate–oxalic acid and further modifying them by treatment with chlorous acid and sodium borohydride. These were dyed with two purified direct dyes to equilibrium at 95°C, and their thermodynamic affinities for these substrates were determined, assuming various extents of ionization of carboxyl groups present in them. It has been shown that the affinity decreases with increase in carboxyl value of the oxycelluloses if the carboxyl groups are assumed to be un-ionized and increases with increasing carboxyl value if they are considered to be fully ionized. |
