title: Leaching zinc from spent catalyst: process optimization using response surface methodology.
abstract: The spent catalyst from vinyl acetate synthesis contains large quantity of zinc. The present study attempts to leach zinc using a mixture of ammonia, ammonium carbonate and water solution, after microwave treatment. The effect of important parameters such as leaching time, liquid/solid ratio and the ammonia concentration was investigated and the process conditions were optimized using surface response methodology (RSM) based on central composite design (CCD). The optimum condition for leaching of zinc from spent catalyst was identified to be a leaching time of 2.50 h, a liquid/solid ratio of 6 and ammonia concentration 5.37 mol/L. A maximum of 97% of zinc was recovered under the optimum experimental conditions. The proposed model equation using RSM has shown good agreement with the experimental data, with a correlation coefficient (R(2)) of 0.95. The samples were characterized before and after leaching using X-ray diffraction (XRD), nitrogen adsorption and scanning electron microscope (SEM).
authors.affiliation: Key Laboratory of Unconventional Metallurgy (Kunming University of Science and Technology), Ministry of Education, Kunming 650093, China.
authors.forename: Zhengyong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jinhui
authors.initials: J
authors.lastname: Peng
authors.forename: C
authors.initials: C
authors.lastname: Srinivasakannan
authors.forename: Zebiao
authors.initials: Z
authors.lastname: Zhang
authors.forename: Libo
authors.initials: L
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Fernández
authors.forename: J A
authors.initials: JA
authors.lastname: Menéndez
mesh_terms: D000641:Ammonia; D002384:Catalysis; D003247:Conservation of Natural Resources / Q000379:methods; D007220:Industrial Waste / Q000517:prevention & control*; D008872:Microwaves; D012995:Solubility; D014753:Vinyl Compounds / Q000138:chemical synthesis; D015032:Zinc / Q000302:isolation & purification*
chemical_list: D007220:Industrial Waste; D014753:Vinyl Compounds; D000641:Ammonia; D015032:Zinc; C011566:vinyl acetate