Synthesis of pectin hydrogel /Fe3O4/Bentonite and its use for the adsorption of Pb (II), Cu (II), and Cd (II) heavy metals from aqueous solutions

Abstract

The magnetic nano adsorbent was prepared by adding Fe3O4 magnetic nanoparticles and bentonite clay into the three-dimensional (3D) cross-linked pectin hydrogel substrate. To determine optimum adsorption conditions, effective factors on the adsorption efficiency of the Pb (II), Cu (II), and Cd (II), including solution pH, adsorbent dosage, contact time, and initial concentration of pollutants, have been experimentally investigated. Thus, in optimum conditions, i.e., contact time (60 min), pH 7, adsorbent dosage (0.03 g), and initial concentration (100 mg/L), the adsorption efficiency of Pb (II), Cu (II), and Cd (II) was obtained at 95.2 %, 92.8 %, and 87.6 %, respectively. The results of the adsorption isotherm studies exhibit a good fit of the data with the Langmuir adsorption isotherm. The obtained kinetic and thermodynamics parameters illustrated that the pseudo-second-order equations, the spontaneous process and endothermic, control the adsorption process.