In this study, the removal of thionine dye from aqueous solutions using low-cost materials as adsorbent by a batch system was investigated.
Experiments were carried out as a function of contact time, initial concentration, pH and temperature. The equilibrium adsorption of
thionine dye on rice husk adsorbent was analyzed by Langmuir, Freundlich and Temkin models. The results indicate that the Langmuir
model provides the best correlation of the experimental data. Various thermodynamic parameters such as enthalpy H°, entropy S° and
free energy G° were evaluated. Thermodynamic parameters values revealed that the adsorption of thionine onto rice husk is endothermic,
spontaneous, with an increased randomness in nature. The results revealed that the thionine is considerably adsorbed on rice husk and it
could be an economical method for the removal of thionine from aqueous systems.
Key words: rice husk, thermodynamic, thionine, isotherm, adsorption
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