Enhanced Photocatalytic Removal of Uranium(VI) from Aqueous Solution by Magnetic TiO₂/Fe₃O₄ and Its Graphene Composite

Abstract

The separation and recovery of uranium from radioactive wastewater is important from the standpoints of environmental protection and uranium reuse. In the present work, magnetically collectable TiO 2 /Fe 3 O 4 and its graphene composites were fabricated and utilized for the photocatalytical removal of U(VI) from aqueous solutions. It was found that, under ultraviolet (UV) irradiation, the photoreactivity of TiO 2 /Fe 3 O 4 for the reduction of U(VI) was 19.3 times higher than that of pure TiO 2 , which is strongly correlated with the Fe 0 and additional Fe(II) generated from the reduction of Fe 3 O 4 by TiO 2 photoelectrons. The effects of initial uranium concentration, solution pH, ionic strength, the composition of wastewater, and organic pollutants on the U(VI) removal by TiO 2 /Fe 3 O 4 were systematically investigated. The results demonstrated its excellent performance in the cleanup of uranium contamination. As graphene can efficiently attract the TiO 2 photoelectrons and thus decrease their transfer to Fe 3 O 4 , the photodissolution of Fe 3 O 4 in the TiO 2 /graphene/Fe 3 O 4 composite can be largely alleviated compared to that of the TiO 2 /Fe 3 O 4 , rendering this ternary composite a much higher stability. In addition, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS) were used to explore the reaction mechanisms.

Titanium Dioxide/Graphene and Titanium Dioxide/Graphene Oxide Nanocomposites: Synthesis, Characterization and Photocatalytic Applications for Water Decontamination

“…The presence of G improved the photocatalytic efficiency as well as decreased the photo dissolution of Fe 3 O 4 compared to TiO 2 /Fe 3 O 4 composites. The prepared nanoparticles were easily recovered by exposure to magnetic fields, thus the recyclability of the nanocomposites was achieved [197].…”

Enhanced Photocatalytic Reduction of Cr(VI) by Combined Magnetic TiO2-Based NFs and Ammonium Oxalate Hole Scavengers

“…However, the recycling efficiency is hindered by the loss of photocatalysts. Considering the secondary pollution caused by the photocatalysts, combining TiO 2 with Fe 3 O 4 to form magnetic composite materials for the magnetic separation under modest magnetic fields has been seen as a benign and effective resolution [25][26][27][28]. To date, there have been many facile methods used to synthesize magnetic iron oxides/TiO 2 hybrid nanomaterial such as sol-gel, metal-organic chemical vapor deposition, the seed-mediated method, and hydrothermal treatment.…”

Photoreduction Processes over TiO2 Photocatalyst

“…This is a reduction path. The use of the electrons from TiO 2 for some reducible metal ions such as Ag(I) [5][6][7][8][9][10][11][12][13], Au(III) [13][14][15][16][17], Cr(VI) [18][19][20][21][22][23], Cu (II) [24][25][26], Hg(II) [27,28], and U(VI) [29,30] has also been developed.…”