Determination of isotherm parameters for the adsorption of Rhodamine B dye onto activated carbon prepared from Ziziphus jujuba seeds

The adsorption of Rhodamine B dye from aqueous solution onto activated carbon prepared from Ziziphus jujuba seed by zinc chloride activation (ZAC) was studied in a batch system with respect to contact time, pH, and temperature. Solution pH 4 was favorable for the adsorption of this dye. Equilibrium isotherms were analysed by Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. The adsorption capacity was found to be 142.9 mg/g by Langmuir isotherm. The Temkin and Dubiniin - Raduskevich isotherm constants suggested that physisorption might be the major mode of the adsorption process. Thermodynamic parameters like ΔG◦, ΔH◦ and ΔS◦ were calculated. These values inferred the spontaneous adsorption with increased randomness at the solid-liquid interface and endothermic behavior.