RB 19 adsorption on activated carbon from pumpkin seeds: Kinetic, isotherm and thermodynamic studies

In this study, the removal of Reactive blue 19 dyestuff in waste water was investigated by adsorption method using activated carbon obtained from pumpkin iner core. Activated carbon obtained from pumpkin iner core activated with ZnCl2 was used as absorbent. In experimental studies, the effects of factor ssuch as adsorption time, amount of absorbent, pH change and temperature on adsorption were investigated, respectively. Pumpkin core hydrochar was characterized by FT-IR, SEM, TGA-DTA, BET and XPS. In the experimental stages, the adsorption equilibrium time was determined as 45 minutes, the adsorbent dosage was 0.8 g and the optimum pH was 6.After this step, the adsorption parameters of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were investigated. It has been pointed out that the adsorption process fits beter with the Freundlich isotherm model, and the adhesion occurs in a multilayered manner and on a heterogeneous surface. Since n ˃ 1' forall n values found in this model, it was interpreted that the adsorption process took place as physical adsorption. Inaddition, the fact that the mean E values in the Dubinin-Radushkevich isotherm are smaller than 8 kJ/mol supports that the bonding mechanism is realized by physical interactions. When the kinetic data were evaluated, it was found to be compatible with the pseudo-second-order kinetic model. In the thermodynamic parameters of adsorption, ΔHo > 0 indicates that the system is endothermic, ΔS° > 0 values increase the disorder of the system, and ΔGo < 0 indicates that the adsorption of dyestuffs on activated carbon is a spontane ous process.