physical is in the range 2.1-20.9 k

physical is in the range 2.1-20.9 kJ/mol and
chemisorption is in the range 80-200 kJ/mol (Lin and
Zhan, 2012). Since the value of DHo
observed in the
system is 24.69 kJ/mol, the removal of humic acid from
peat water using CSC is occurred by physisorption.
The positive value of entropy change (DSo
) indicates
the increased randomness at the solid-solution
interface during the adsorption of humic acid onto CSC
(Gandhi et al., 2010; Fan et al., 2011; Liang et al., 2011;
Rahchamani et al., 2011; Lin and Zhan, 2012; Gandhi
and Meenakshi, 2013a; Wang et al., 2013) and also
reflects the greater affinity of the adsorbent for HA
molecules (Liang et al., 2011).
The other thermodynamic parameter is activation
energy (Ea
). The Arrhenius equation was applied to
evaluate the Ea
of the adsorption process: