Thermodynamic Analysis for Adsorption of Amoxicillin onto Magnetic Carbon Nanotubes

The effect of temperature on the equilibrium adsorption of Amoxicillin (AMO) from aqueous solution using modified magnetic multi-walled carbon nanotubes (MMWCNT_S) was investigated. The equilibrium adsorption data were analyzed using three widely applied isotherms: Langmuir, Freundlich and Tempkin. The results revealed that Langmuir isotherm fit the experimental results well. Kinetic analyses were conducted using pseudo-first and second-order models and the intraparticle diffusion model. The regression results showed that the adsorption kinetics were more accurately represented by pseudo-second-order model. Standard free energy changes (G⁰), standard enthalpy change (H⁰), and standard entropy change (S⁰) were calculated at different temperatures. TheG⁰ values were negative and H⁰ values and S⁰ values of MMWCNT_S were positive; and suggested that the AMO adsorption on MMWCNT_S was a spontaneous and endothermic process.