Synthesis of α-Fe 2 O 3 nanofibers for applications in removal and recovery of Cr(VI) from wastewater

Purpose Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. The purpose of this work is to synthesize α-Fe 2 O 3 nanofibers for potential applications in removal and recovery of noxious Cr(VI) from wastewater. Methods α-Fe 2 O 3 nanofibers were synthesized via a simple hydrothermal route followed by calcination. The crystallographic structure and the morphology of the as-prepared α-Fe 2 O 3 nanofibers were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Batch adsorption experiments were conducted, and Fourier transform infrared spectra were recorded before and after adsorption to investigate the Cr(VI) removal performance and adsorption mechanism. Langmuir and Freundlich modes were employed to analyze the adsorption behavior of Cr(VI) on the α-Fe 2 O 3 nanofibers. Results Very thin and porous α-Fe 2 O 3 nanofibers have been successfully synthesized for investigation of Cr(VI) removal capability from synthetic wastewater. Batch experiments revealed that the as-prepared α-Fe 2 O 3 nanofibers exhibited excellent Cr(VI) removal performance with a maximum adsorption capacity of 16.17 mg g −1 . Furthermore, the adsorption capacity almost kept unchanged after recycling and reusing. The Cr(VI) adsorption process was found to follow the pseudo-second-order kinetics model, and the corresponding thermodynamic parameters Δ G °, Δ H °, and Δ S ° at 298 K were calculated to be −26.60 kJ mol −1 , −3.32 kJ mol −1 , and 78.12 J mol −1 K −1 , respectively. Conclusions The as-prepared α-Fe 2 O 3 nanofibers can be utilized as efficient low-cost nano-absorbents for removal and recovery of Cr(VI) from wastewater.