title: Study on reaction kinetics and selective precipitation of Cu, Zn, Ni and Sn with H₂S in single-metal and multi-metal systems.
abstract: Determination of reaction kinetics and selective precipitation of Cu, Zn, Ni and Sn with H(2)S in single-metal and multi-metal systems were studied to develop a process of metal recovery from plating wastewater. As samples, single-metal model wastewaters containing Cu, Sn, Zn or Ni, and multi-metal model wastewater containing Cu-Zn-Ni or Sn-Zn mixtures were used. In both single-metal and multi-metal systems, the pH value was precisely controlled at a value of 1.5 for CuS and SnS precipitation, 4.5 for ZnS precipitation and 6.5-7.0 for NiS precipitation. Subsequently, the sulfidation of Cu, Sn, Zn and Ni was evaluated. It was found that an amount of H(2)S equimolar to a given metal was sufficient to achieve almost complete precipitation of the particular metal. Further, the selectivity of metal precipitation was found to be higher than 95% in the Cu-Zn-Ni multi-metal system and higher than 91% in the Sn-Zn system. It was also found that the sulfidation reaction proceeded in accordance with Higbie's penetration theory and reaction rate constants and mass-transfer coefficients under various experimental conditions were determined. Finally, the reaction rate constants obtained in single-metal and multi-metal systems were found to be almost the same indicating that the precipitation of a particular metal was not significantly affected by the presence of other components.
authors.affiliation: Department of Energy Engineering and Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tokuda
authors.forename: D
authors.initials: D
authors.lastname: Kuchar
authors.forename: N
authors.initials: N
authors.lastname: Mihara
authors.forename: M
authors.initials: M
authors.lastname: Kubota
authors.forename: H
authors.initials: H
authors.lastname: Matsuda
authors.forename: T
authors.initials: T
authors.lastname: Fukuta
mesh_terms: D011232:Chemical Precipitation; D003300:Copper / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis; D007700:Kinetics; D008669:Metallurgy; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D014001:Tin / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D014001:Tin; D003300:Copper; D009532:Nickel; D015032:Zinc; D006862:Hydrogen Sulfide