Sodium Hydroxide-Treated Beta-Cyclodextrin Hydrochar for Malachite Green Removal

In this work, beta cyclodextrin hydrochar was treated using sodium hydroxide for malachite green removal. The adsorbents were characterized for surface functionalities, thermal decomposition and morphology. The functionalized hydrochar exhibits the adsorption-precipitation mechanisms with maximum capacity of 76.9 mg/g, prior to surface neutralization by dye solution that results in the decrease of capacity. The equilibrium curve for adsorption- precipitation regime obeys Freundlich model, while the kinetic follows pseudo- first order model, both suggesting the physical adsorption process. From the thermodynamic perspective, the process is exothermic and spontaneous.