A rapid azo dye decolorization of methyl orange by the foam zero-valent nickel

In this article, foam zero-valent nickel (FZVN) was put forward as a promising zero-valent metal for the pretreatment of azo dye wastewater (MO as a model contaminant). The characteristics of FZVN were evaluated by methods of Barrett-Emmett-Teller, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Moreover, influence of key experimental parameters, including oxygen concentration, presence of different acid, pH, and temperature on the MO decolorization were systematically ascertained. Furthermore, possible mechanism of MO removal by FZVN was investigated by using Liquid chromatography-mass spectrometry (LC-MS). Results showed that FZVN was a three-dimensional pore material with a specific surface area of 3 m 2 g −1 . Moreover, anoxic condition, presence of acetic acid, higher temperatures and acid conditions were beneficial to decolorize MO by FZVN while the decolorization process obeyed the first order kinetic model with an apparent rate constant ( k app ) of 0.162 min −1 at pH value of 4 (25°C). The activation energy E a obtained from the decolorization reaction was 83.1 kJ mol −1 . Based on LC-MS results, the role of FZVN in the decolorization reaction process was suggested as follows: strong reductive, catalysis, and adsorption. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 686–694, 2018