title: Supercritical water oxidation of sulfide.
abstract: Supercritical water oxidation (SCWO) of sulfide wastewater with oxygen as the oxidant was investigated using ammonium sulfide solution as the model waste. The experiments, which were conducted in a bench-scale continuous SCWO installation, indicated that S2- could be completely oxidized to SO4(2-) within the residence time of less than 10 s under the supercritical water conditions at 698.2-773.2 K and 22.0 MPa-30.0 MPa. The reaction pathway of S2- in SCWO was determined to be S2- --> S2O3(2-) --> SO3(2-) --> SO4(2-). The effects of temperature, pressure, and oxygen content on SCWO of S2- were also studied. The kinetic model based on this pathway was established with the reaction rate constants and orders found by fitting the experimental data. The dependence of the rate constants on the temperature can be described with Arrhenius' law. The rate constants are dependent on the density of SCW, and the dependence is logarithmically linear.
authors.affiliation: Department of Chemical Engineering, Tsinghua University, Beijing 100084, China. taowang@tsinghua.edu.cn
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Botao
authors.initials: B
authors.lastname: Xiang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Zhongyao
authors.initials: Z
authors.lastname: Shen
mesh_terms: D007700:Kinetics; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010100:Oxygen; D011312:Pressure; D013440:Sulfides / Q000737:chemistry*; D013696:Temperature; D014865:Waste Disposal, Fluid
chemical_list: D013440:Sulfides; D010100:Oxygen