SOLUTION COMBUSTION SYNTHESIS OF MGAL₂O₄ AT 800OC SPINEL NANOPARTICLES: STRUCTURAL CHARACTERISATION AND PHOTOCATALYTIC DEGRADATION OF CORALENE DARK RED 2B

Abstract

MgAl₂O₄ nanoparticles were prepared by solution combustion of magnesium and aluminium nitrates with urea as fuel, followed by calcination at 800 °C. XRD showed phase-pure cubic spinel (JCPDS 21-1152, Fd-3m) with no MgO or Al₂O₃ impurities. UV–Vis spectroscopy showed strong absorption below 250 nm and almost none in the visible range. TEM showed rounded, partly fused grains of about 100–300 nm, and SAED confirmed their crystallinity. SEM showed angular, micrometre-sized aggregates, and EDX detected only O, Mg and Al. Photocatalytic activity was tested on 200 ppm Coralene Dark Red 2B under LED light (1200 µmol m⁻² s⁻¹ PAR, pH 7, 180 min) at ten catalyst loadings (1.6–130 g L⁻¹), with dark controls run in parallel. Dye removal stayed above 96.5% at every loading, reaching 99.8% in the light and 99% in the dark. Light and dark results were close, so adsorption on the powder accounted for most of the removal.