The thermal properties of NO3--intercalated Mg-Al layered double hydroxide (NO3 center dot Mg-Al LDH) were investigated using simultaneous thermogravimetry-mass spectrometry (TG-MS), and the elimination behavior of nitrogen oxides from this double hydroxide was examined. The TG-MS results showed that NO3 center dot Mg-Akl LDH decomposed in four stages. The first stage involved evaporation of surface adsorbed water and interlayer water in NO3 center dot Mg-Al LDH. In the second and third stages, dehydroxylation of the brucite-like octahedral layers in NO3 center dot Mg-Al LDH occurred. The fourth stage mainly corresponded to the elimination of NO3-intercalated in the Mg-Al LDH interlayers to afford NO2. Thermal decomposition of NO3 center dot Mg-Al LDH at 400-600 degrees C resulted in the formation of Mg-Al oxide, and the produced NO2 reacted with H2O and O-2 to form HNO3 and HNO2. The elimination of nitrogen oxides was found to increase with time and decomposition temperature. The synthesized Mg-Al oxide mixture could be used to remove nitric acid from aqueous solutions. (C) 2009 Elsevier B.V. All rights reserved.