The enhanced photocatalytic reduction of U(VI) on MoS2/g-C3N4 in the presence of Cr(VI) and tetracycline

The synergistic removal of various pollutants is the challenge of environmental remediation due to mutual interference. The effect of Cr(VI) and tetracycline (TC) on photocatalytic reduction of U(VI) by MoS2/g-C3N4 was investigated by batch and spectroscopic techniques. The high adsorption of U(VI) on MoS2/g-C3N4 and the negative influence of photo-irradiation on U(VI) removal at pH 4.5 were observed. The batch experiments showed that the presence of TC and Cr(VI) improved the photoreduction of U(VI), whereas photocatalytic removal of Cr(VI) and TC were not influenced significantly. The adsorbed U(VI) was primarily photo-reduced into U(IV), while U(IV) was re-oxidized into U(VI) with further increasing irradiation by XPS analysis. According to quenching experiments, photo-degradation of TC was attributed to photogenerated holes, while the photo-reduction of Cr(VI) and U(VI) were due to center dot O2  and center dot OH radicals, respectively. These findings are crucial for the application of g-C3N4-bearing composites in the synergistic removal of radionuclide, heavy metal and organic at actual environmental cleanup.