Reactive Blue 19 Adsorption on Activated Carbon from Pumpkin (Cucurbita Pepo) Seed Waste: Kinetic, Isotherm and Thermodynamic Studies

Abstract

In this study, the removal of reactive blue 19 dyestuffs in aqueous systems was investigated by the adsorption method using activated carbon obtained from pumpkin seed waste. Activated carbon obtained from pumpkin seed waste functionalized with ZnCl2 was used as an absorbent. Pumpkin seed 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 6.0. 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 better with the Freundlich isotherm model, and the adhesion occurs in a multilayered manner and on a heterogeneous surface. Freundlich and Dubinin-Radushkevich isotherms support that the bonding mechanism is realized by physical interactions. When the kinetic data were evaluated, adsorption mechanism was found to be compatible with the pseudo-second-order kinetic model. The thermodynamic parameters of adsorption indicate that the system is endothermic, and the adsorption of reactive blue 19 on activated carbon is a spontaneous process.