title: Wet air oxidation and catalytic wet air oxidation for dyes degradation.
abstract: OBJECTIVE
  Textile industry produces wastewater which contributes to water pollution since it utilizes a lot of chemicals. Preliminary studies show that the wastewater from textile industries contains grease, wax, surfactant, and dyes. The objective of this study was to determine the treatment efficiency of the nickel catalysts supported on hydrotalcites in three-dye model compounds and two types of wastewater.
  
  
  METHODS
  Hydrotalcites were employed to prepare supported nickel catalysts by wetness impregnation technique. Metal loadings from 1 to 10 wt% were tested. Catalysts were characterized by several techniques. They were tested in a catalytic wet air oxidation of three dyes and two wastewaters with different origins.
  
  
  CONCLUSIONS
  It could be observed that the higher the metal content, the lower the BET area, possibly due to sintering of Ni and the consequent blocking of the pores by the metal. In addition, metallic dispersion was also higher when the metal content was lower. Dye conversion was more than 95% for every catalyst showing no differences with the nickel content. A high degree of dye conversion was achieved. Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) processes have been proved to be extremely efficient in TOC removal for wastewaters.
  
  
  CONCLUSIONS
  The CWAO process can be used to remove dyes from wastewater. Three different dyes were tested showing satisfactory results in all of them. TOC degradation and dye removal in the presence of the catalyst were effective. Also, the HTNi catalyst is very active for organic matter and toxicity removal in wastewaters.
authors.affiliation: Grupo de Catálisis y Procesos de Separación, Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain. govejero@quim.ucm.es
authors.forename: Gabriel
authors.initials: G
authors.lastname: Ovejero
authors.forename: José Luis
authors.initials: JL
authors.lastname: Sotelo
authors.forename: Araceli
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Ana
authors.initials: A
authors.lastname: Vallet
authors.forename: Juan
authors.initials: J
authors.lastname: García
mesh_terms: D000388:Air; D000536:Aluminum Hydroxide / Q000378:metabolism; D001673:Biodegradation, Environmental; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry*; D007220:Industrial Waste; D008276:Magnesium Hydroxide / Q000378:metabolism; D009532:Nickel / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction; D013783:Textile Industry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; C010467:hydrotalcite; D000536:Aluminum Hydroxide; D009532:Nickel; D008276:Magnesium Hydroxide