Adsorption of Antibiotic Drug on the Surface of Humic Acid Modified Magnetite Nanoparticles: Kinetics, Isotherm and Thermodynamic Studies

Abstract

The present study reports the synthesis of humic acid-modified magnetite nanoparticles for adsorption behaviour towards the ofloxacin drug. Several analytical and spectroscopic techniques were used to characterize the synthesized surface modified magnetite nanoparticles. In order to determine the highest possible adsorption capacity of these coated nanoparticles, the effects of various influencing variables such as pH of the solution, contact time, initial concentration of adsorbate solution, amount of adsorbent and temperature were also investigated using batch adsorption method. Adsorption isotherm and kinetic analysis for the adsorption of ofloxacin drug from aqueous solution were studied simultaneously. The kinetics and isotherm studies demonstrated good agreement with the pseudo-second-order kinetics model and Langmuir model of isotherm, respectively. Thermodynamic analysis of the adsorption of ofloxacin on the surface of humic acid modified magnetite nanoparticles displayed negative values of Gibb’s free energy change, positive values of enthalpy as well as entropy change, resulting that the adsorption process was spontaneous and endothermic in nature. A comparative study of percentage drug removal efficiency of humic acid functionalized magnetite nanoparticles with the reported adsorbents has also been reported. This study revealed that the humic acid-modified magnetite nanoparticles showed remarkable adsorption capacity and thus could be used as an effective adsorbent for the removal of ofloxacin from aqueous solution.