Good compliance with the pseudo-second-order kinetic model
and the Langmuir model justified the chemical nature of the Cu2+
adsorption. Besides, fast adsorption process (the time of adsorption
equilibrium in less than 5 min) indicates that this type of adsorption
behavior is typical of the specific adsorption process in which
the adsorption rate is usually dependent upon the number of available
adsorption sites on the adsorbent. Based on this result, the following
points were considered in order to explore the mechanisms
for the enhanced Cu2+ adsorption onto carbonaceous sulfurcontaining
chitosan–Fe(III):