Enhancement of the Cr(VI) adsorption and photocatalytic reduction activity of g-C₃N₄by hydrothermal treatment in HNO₃aqueous solution

Hongtao Wei, Qian Zhang, Yongcai Zhang*

Jiangsu Key Laboratory of Environmental Material and Environmental Engineering, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China

Abstract

An effective and environmental-friendly method was adopted to enhance the Cr(VI) adsorption and photocatalytic reduction activity of g-C₃N₄, which was prepared by thermal condensation of melamine. The enhancement was realized by hydrothermal treatment of g-C₃N₄in 1.9–7.6 mol/L HNO₃aqueous solutions at 80–120 ◦C for 3–12 h. The compositions, structures and physiochemical properties of the hydrothermally treated g-C₃N₄were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N₂adsorption/desorption isotherms, Zeta potential analysis, UV–vis diffuse reflectance spectroscopy and photocurrent measurement, and their dark adsorption and visible-light (wavelength > 420 nm)-driven photocatalytic reduction of Cr(VI) in aqueous solution were tested. It was found that the hydrothermally treated g-C₃N₄exhibited significantly enhanced Cr(VI) adsorption and photocatalytic reduction activity than g-C₃N₄. Moreover, larger concentration of HNO₃aqueous solution, higher hydrothermal temperature or longer treatment time resulted in higher Cr(VI) adsorption and photocatalytic reduction activity of the hydrothermally treated g-C₃N₄. The reasons accounting for the enhanced

Cr(VI) adsorption and photocatalytic reduction activity of the hydrothermally treated g-C₃N₄were discussed, and the different mechanisms for the photocatalytic reduction of Cr(VI) over g-C₃N₄and the hydrothermally treated g-C₃N₄were also proposed.

Applied Catalysis A: General, 2016, 521, 9-18.

文章链接：http://www.sciencedirect.com/science/article/pii/S0926860X15302337

文章附件：Appl. Catal. A-2016-521- 9

Applied Catalysis A General,2016,521, 9-18