title: Removal of binary dyes mixtures with opposite and similar charges by adsorption, coagulation/flocculation and catalytic oxidation in the presence of CeO2/H2O2Fenton-like system.
abstract: In this study, the removal of binary mixtures of dyes with similar (Orange II/Acid Green 25) or opposite charges (Orange II/Malachite Green) was investigated either by simple adsorption on ceria or by the heterogeneous Fenton reaction in presence of H2O2. First, the CeO2nanocatalyst with high specific surface area (269 m2/g) and small crystal size (5 nm) was characterized using XRD, Raman spectroscopy and N2physisorption at 77 K. The adsorption of single dyes was studied either from thermodynamic and kinetic viewpoints. It is shown that the adsorption of dyes on ceria surface is highly pH-dependent and followed a pseudo-second order kinetic model. Adsorption isotherms fit well the Langmuir model with a complete monolayer coverage and higher affinity towards Orange II at pH 3, compared to other dyes. For the (Orange II/Acid Green 25) mixture, both the amounts of dyes adsorbed on ceria surface and discoloration rates measured from Fenton experiments were decreased by comparison with single dyes. This is due to the adsorption competition existing onto the same surface Cex+sites and the reaction competition with hydroxyl radicals, respectively. The behavior of the (Orange II/Malachite Green) mixture is markedly different. Dyes with opposite charges undergo paired adsorption on ceria as well as homogeneous and heterogeneous coagulation/flocculation processes, but can also be removed by heterogeneous Fenton process.
authors: Université de Lorraine, Laboratoire de Chimie et Physique Approche Multi-échelle des Milieux Complexes (LCPA2MC), EA n° 4632, Institut Jean Barriol, Rue Victor Demange, 57500, Saint-Avold, France.
authors: Houeida
authors: H
authors: Issa Hamoud
authors: Université de Lorraine, Laboratoire de Chimie et Physique Approche Multi-échelle des Milieux Complexes (LCPA2MC), EA n° 4632, Institut Jean Barriol, Rue Victor Demange, 57500, Saint-Avold, France. Electronic address: gisele.finqueneisel@univ-lorraine.fr.
authors: Gisèle
authors: G
authors: Finqueneisel
authors: Université de Lorraine, Laboratoire de Chimie et Physique Approche Multi-échelle des Milieux Complexes (LCPA2MC), EA n° 4632, Institut Jean Barriol, Rue Victor Demange, 57500, Saint-Avold, France.
authors: Bruno
authors: B
authors: Azambre
mesh_terms: D000327:Adsorption; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry*; D005427:Flocculation; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D014874:Water Pollutants, Chemical
chemical_list: D004396:Coloring Agents; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide
keywords: Adsorption isotherm; Advanced oxidation processes; Degradation; Hydrogen peroxide; Kinetics