In recent years, environmental pollution in the dyeing industry has
aroused great public concern and substantial researches were focused
on solving the problem [1–5]. Reactive dyes are a kind of popular dyes
for cotton dyeing due to their excellent properties, such as wide range
of hue, brilliancy and good wet fastness. However, owing to the low affinity
between the dyes and the fibers, a large amount of salt
(30–100 g·L−1), such as sodium sulfate or sodium chloride, is added
in the dyebath to promote dye adsorption in the exhaust dyeingmethod
[6]. As it is not consumed during dyeing process, the added salt is all released
after dyeing. However, the salt-containing dye wastewater is
quite difficult to deal with and does great harm to the environment. In
order to solve the problem, cationization of cotton has been widely
studied in recent years for effective adsorption of reactive dyes in the
absence of salt [7–15]. Among the cationic agents used, most of them
are synthetic compoundswhich may present safety problemin application.
Although some biopolymers or their derivatives, such as chitosan
and its derivative, have been studied, the polymers on cotton may prevent
dye penetration into the fibers and influence dye fixation. In addition,
the existence of cationic groups on cotton surface easily leads to