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 (MMWCNTS) 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. The △G0 values were negative and △H0 values and △S0 values of MMWCNTS were positive; and suggested that the AMO adsorption on MMWCNTS was a spontaneous and endothermic process.