Formation of copper hydroxy double salts derived from metal oxides and their catalytic activity in degradation of methyl orange

Abstract

© 2018 Elsevier Ltd and Techna Group S.r.l. This work reports the preparation and application of copper hydroxy double salts (Cu-M HDS) as catalysts for degradation of a model wastewater dye pollutant, methyl orange (MO), under ambient conditions. The Cu-M HDS (M = Ca, Zn, La and Pb) were derived in 30 min from hydrothermal treatment of aqueous copper (II) nitrate and the corresponding metal oxide. All Cu-M HDS systems were highly active for catalytic wet oxidation (CWO) of MO, with complete oxidation of 500 ppm MO possible in less than 10 min under ambient (pH 7.0, 30 °C) conditions, with no requirement for additional oxidants. Dissolved oxygen is crucial for activity, as indicated by poor conversions under anaerobic conditions. Decolorization follows first-order kinetics, with catalyst systems having high surface area and Cu content (Cu-Ca HDS, Cu-La HDS) being most rapid. These features, coupled with favorable reusability profiles and ease of fabrication and use, highlight the potential of Cu-M HDS systems in water remediation strategies.