Phosphine-functionalized Fe3O4/SiO2/composites as efficient magnetic nanoadsorbents for the removal of palladium ions from aqueous solution: Kinetic, thermodynamic and isotherm studies

Abstract

The aim of this study was to remove palladium ions from aqueous media in a batch operating system. A newly synthesized magnetic Fe3O4/SiO2/OPPh2 (diphenylphosphinite) nanocomposite was used as the adsorbent. This nanocomposite was examined by Fourier transform infrared, thermogravimetric analysis and X-ray spectroscopy methods. The factors that influence the adsorption equilibrium were examined, such as pH value, adsorbent dosage, metal concentration, adsorption time, temperature, influence of desorption solutions, concentration of the desorption solution and the influence of the ions present at the same time, namely Cd2 +, Ni2 +, Ca2 +, Co2 +, Fe3 +, Ba2+and Pt4+were determined based on the adsorbent used (Fe3O4/SiO2/OPPh2). Under optimal conditions and at the same concentrations, the interfering ions have only a very slight influence on the Pd (II) uptake. Finally, the first and second pseudo diagrams at temperatures of 20, 30 and 40 °C drew and the related value of R2 was calculated. As a result, we follow the second pseudo-diagram at 20 °C, the first pseudo-diagram at 30 °C and the second pseudo-diagram at 40 °C. The best fits at temperatures of 20, 30 and 40 °C were Generalized, Jossens, Fritz-Schlunder, and Weber-van Viel isotherm models respectively. It was found that the fit isotherm is the Fritz-Schlunder model. The best possible model was determined in advance on the basis of error functions. Thermodynamic parameters indicate the endothermic, irreversible and nonspontaneous nature of the adsorption. In addition, the useful application of the method presented was examined using the adsorption of palladium from the two different water samples.