For the adsorption process, two commonly used reactor modes
are the fixed bed reactor and the stirred tank reactor. Since hydrogel
is a flexible material and often used in particle form, use in the form
of fixed-bed columns is not appropriate because of the compaction,
pressure drop, and resulting slow speed of thewater flowacross the
column. Additionally, there are associated clogging problems and
mass transfer limitations (Gomez-Pastora et al., 2014). To avoid
such issues, stirred tank reactors are alternatively used in which the
hydrogel is suspended in solution. However, this contact mode
requires subsequent separation of the hydrogel from solution after
the completion of adsorption or desorption stage. If the hydrogel
particle size is too small