Enhanced Chromium Sorption and Quick Separation of Magnetic Hydrotalcite Anchored Biopolymeric Composites Using the Hydrothermal Method

Abstract

The magnetic hydrotalcite supported biopolymeric composites were synthesized by hydrothermal (Hydro) and in situ precipitation (in situ) methods for selective chromium removal. A comparative evaluation of chromium sorption capacity (SC) of both hydrothermal and in situ synthesized magnetic biocomposites namely Fe3O4@alginate/hydrotalcite (Fe3O4@AlgHT) composite, Fe3O4@chitosan/hydrotalcite (Fe3O4@CSHT) composite, and Fe3O4@gelatin/hydrotalcite (Fe3O4@GelHT) composite was carried out. The hydrothermally synthesized magnetic biocomposites demonstrated greater chromium SC than in situ method. The synthesized materials were characterized by Fourier transform infrared spectrometer, X-ray diffraction, Brunauer–Emmett–Teller, ultraviolet–visible spectrophotometer, vibrating sample magnetometer, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray analysis. The equilibrium data of the synthesized magnetic biocomposites were explained by Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherms. The thermodynamic result shows that the nature of chromium sorption onto the magnetic biocomposites is spontaneous and endothermic. The kinetic models suggested that the chromium sorption behavior follow pseudo-second-order and intraparticle diffusion models. The chromium sorbed magnetic biocomposites can be easily regenerated using NaOH and can be effectively used up to five cycles. The suitability of the magnetic biocomposites at field conditions was inspected by field water sample.