title: Selective recovery of chromium, copper, nickel, and zinc from an acid solution using an environmentally friendly process.
abstract: OBJECTIVE
  Real electroplating effluents contain multiple metals. An important point related with the feasibility of the bioremediation process is linked with the strategy to recover selectively metals. In this work, a multimetal solution, obtained after microwave acid digestion of the ashes resulted from the incineration of Saccharomyces cerevisiae contaminated biomass, was used to recover selectively chromium, copper, nickel, and zinc.
  
  
  RESULTS
  The acid solution contained 3.8, 0.4, 2.8, and 0.2 g/L of chromium(III), copper, nickel, and zinc, respectively. The strategy developed consisted of recovering copper (97.6%), as a metal, by electrolyzing the solution at a controlled potential. Then, the simultaneous alkalinization of the solution (pH 14), addition of H(2)O(2), and heating of the solution led to a complete oxidation of chromium and nickel recovery (87.9% as a precipitate of nickel hydroxide). After adjusting the pH of the remaining solution at pH 10, selective recovery of zinc (82.7% as zinc hydroxide) and chromium (95.4% as a solution of cromate) was achieved.
  
  
  CONCLUSIONS
  The approach, used in the present work, allowed a selective and efficient recovery of chromium, copper, nickel, and zinc from an acid solution using a combined electrochemical and chemical process. The strategy proposed can be used for the selective recovery of metals present in an acid digestion solution, which resulted from the incineration of ashes of biomass used in the treatment of heavy metals rich industrial effluents.
authors.affiliation: Bioengineering Laboratory, Chemical Engineering Department, Superior Institute of Engineering from Porto Polytechnic Institute, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto, Portugal.
authors.forename: Manuela D
authors.initials: MD
authors.lastname: Machado
authors.forename: Eduardo V
authors.initials: EV
authors.lastname: Soares
authors.forename: Helena M V M
authors.initials: HM
authors.lastname: Soares
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D003300:Copper / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D004595:Electroplating; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D019216:Metals, Heavy / Q000737:chemistry* / Q000378:metabolism; D009532:Nickel / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D002857:Chromium; D003300:Copper; D009532:Nickel; D015032:Zinc