Bentonite coated with magnetite Fe3O4 nanoparticles as a novel adsorbent for copper (II) ions removal from water/wastewater

In the present work, the natural bentonite (NB) coated with synthesized Fe3O4 magnetite nanoparticles (CB) was firstly used as an adsorbent to sequester Cu(II) ions from the polluted solutions. The characterization study demonstrated a substantial improvement in several adsorptive parameters of NB after coating, like surface area, surface morphology and topography. From the analysis of the pore diameters, it was observed that the CB lies in the mesoporous materials category with diameters in the range of 2-50 nm. The removal efficiency was optimized as a function of the parameters: pH (3-6), CB dose (0.2-1 g/100 mL solution), and initial Cu(II) concentration (up to 200 mg/L). The results of the isotherm study revealed that the experimental data were fitted well onto the Langmuir model with the maximum amount of Cu(II) (46.948 mg/g) being adsorbed at pH 6, when the CB dose was 0.5 g and it shaking was done at 200 rpm speed, in a reaction time of 120 min. The kinetics of Cu(II) adsorption was chemosorption in nature as confirmed by the fitting with pseudo-second-order model. In addition, the results showed that the intraparticle diffusion was not the dominating mechanism. Comparison of the results of this study and those obtained from literature, it suggests that the CB exhibits an excellent sorption capacity for the Cu(II) removal and, therefore, can be used as a potential material in the adsorption systems for Cu(II) removal from rich wastewater.