Abstract
Magnetic Fe3O4 (FO) nanocubes coated by SiO2 (FO–S) and TiO2 (FO-T) layers with perfect adsorption characteristics were successfully fabricated by a simple technique, and characterized by Fourier-transform infrared spectroscopy (FTIR), Field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), High resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS) and Brunauer-Emmett-Teller (BET) specific surface area. HR-TEM analysis confirms the susccess of Fe3O4 coating with TiO2 and SiO2 with a shell thickness ranged from 24 to 33 nm and 12–16 nm, respectively. Cr (VI) elimination from wastewater by the fabricated materials was carried out using a batch adsorption method at varying initial [Cr(VI)] (10–200 ppm), initial pH (1–8), shaking speed (200–400 rpm), temperature (293–333 K), contact time (0–180 min) and adsorbent dose (0.1–0.5 g). The point of zero charges (PZC) for adsorbents was estimated. The equilibrium findings of Cr (VI) ions removal were illustrated by Freundlich and Langmuir isotherm models and their kinetic results of ions were followed the pseudo-second-order sorption. The maximum adsorption capacity of Cr (VI) onto FO, FO-T, and FO-S were estimated to be 25.3, 28.7 and 32.6 mg/g, respectively. Further, the utilized adsorbents can be readily renovated and the adsorption capacity was still excellent after six sorption-regeneration cycles.
[Display omitted]
•Magnetic Fe3O4 nanocubes coated by SiO2 and TiO2 layers were successfully fabricated.•The prepared materials showed good stability, regeneration activity, and adsorption efficiency for Cr(VI) removal.•The thermodynamic study, adsorption isotherm, kinetics study, and pH influence were investigated in batch experiments.•The maximum adsorption capacity of Cr (VI) was 32.6 mg/g