Modeling of adsorption kinetic and equilibrium isotherms of naproxen onto functionalized nano-clay composite adsorbent

Abstract

In this research, nano-clay was firstly modified with β-cyclodextrin and polymerized by polyvinylpyrrolidone (PVP) to provide more surfaces for higher adsorption. The adsorption process as batch study was investigated under the experimental conditions affecting some parameters such as pH, contact time, concentration of naproxen and the amount of adsorbent for adsorption efficiency. Then, the adsorption kinetic and equilibrium isotherms were also studied. The results showed that the adsorption was influenced by some factors such as initial concentration of naproxen, the amount of adsorbent and solution's pH. The optimum values of adsorbent dosage, contact time, initial naproxen concentration and pH were evaluated as 1g, 120min, 10mg/l and 6, respectively. Also, the maximum efficiency of adsorption was achieved 92.2%. The equilibrium constant was studied with 9 more common isotherm models, and among them, all isotherm models could well describe the adsorption of naproxen on the modified nano-composite except Langmuir and Tempkin models that show large deviation from experimental data. This was confirmed by investigating the results of error function analysis. Moreover, it was indicated that the adsorption follows Elovich kinetic model. Based on the obtained results, it can be stated that the adsorption method using the modified nano-composite is an efficient, facile and reliable method for the removal of naproxen from aqueous solutions.