Cetyl trimethyl ammonium bromide (CTAB), was used as surfactant to enhance
the removal of Congo- red (C-R) dye from its solution by employing a wood of
buckthorn tree as a low cost and eco-friendly adsorbent. Different factors affecting
the sorption process like, time of adsorption, wood dose, initial (C-R) concentration
and hydrogen ion concentration have been studied for both adsorbent wood (W) and
modified wood (MW). The suitability of the two isotherm models Langmuir and
frundlich to the equilibrium results was mentioned for the adsorption of (C-R) on
both wood and modified wood. From the value of correlation - factor, frundlich
model give a better fit than Langmuir isotherm model. Thermodynamic function
such as the changes in enthalpy ΔH°, entropy ΔSo and Gibes free energy ΔGo for the
adsorption process was guessed. These values illustrate that physi-sorption take
place .The negative values of ΔHo shows that the adsorption process accompany
with heat releasing with decreasing the randomness of the (solid-solution) interface.
Furthermore the negative values of ΔG° indicated that adsorption of (C-R) dye onto
the wood and modified wood occurs spontaneously.
