Biosorption study of Cd2+ ions onto activated carbon prepared from Posidonia oceanica Seagrass: Kinetics and thermodynamics studies

In this research, the synthesis and characterization of activated carbon from Posidonia oceanica seagrass have been carried out through physical activation (AC-PO) as a biosorbent for Cd²⁺ ions in solution. The physical activation process was carried out at a temperature of 600 °C and physical activation was carried out using the water-steam activator. The objective of the AC-PO biosorption test on Cd²⁺ ions is to ascertain the optimal contact time, the impact of temperature, the influence of concentration, the ideal dose, and pH, in addition to the kinetic model and biosorption isotherm pattern. The biosorption kinetics data of Cd²⁺ ions on AC-PO tend to follow a pseudo-second-order kinetic model. The biosorption isotherms of Cd²⁺ ions on AC-PO tend to follow the Langmuir, Freundlich, Temkin, and D-R isotherm models with a correlation coefficient (R²) of >0.9910. The thermodynamic parameters such as ΔG^o, ΔH^o, and ΔS^o were calculated for the Cd²⁺ ion, and it was determined that the biosorption was spontaneous and endothermic.