Synthesis and characterisation of Penta-bismuth Hepta-oxide nitrate, Bi 5O 7NO 3, as a new adsorbent for methyl orange removal from an aqueous solution

Abstract

This paper presents the synthesis of penta-bismuth hepta-oxide nitrate, Bi 5O 7NO 3, via the chemical precipitation method. After calcination, the precipitate was characterised by several methods, which included X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, BET surface area and pH drift method to determine the pH of point of zero charge (pHpzc). The study results revealed that Bi 5O 7NO 3 had an orthorhombic crystal structure, a surface area of 1.6 m 2 g -1and a point of zero charge at pH 9.7. The chemical state of Bi 5O 7NO 3 indicated the presence of three oxidation states of bismuth centre. Furthermore, the decolourization ability of Bi 5O 7NO 3 to remove the azo dye was also evaluated. Although it had lower surface area, the removal efficiency was extremely good. This finding suggests that Bi 5O 7NO 3 could be used as a promising adsorbent for azo dye removal. The XPS spectra showed © 2012 Hindawi Publishing Corporation.