Formation of metallic and metal hydrous oxide dispersions

The formation, via hydrothermally induced precipitation from homogeneous solution, of a variety of well-defined dispersions of metallic and hydrous metal in the conditions under which the particles are produced (e.g., pH and composition of the growth medium, aging temperature, rate of heating, or degree of agitation) can be readily discerned by following changes in the mass, composition, and morphology of the final solid phase. The generation of colloidal dispersions in the absence of gravity convection or sedimentation effects may result in the appearance of morphological modifications not previously observed in terrestrially formed hydrosols

Photo-Fenton Degradation of the Herbicide 2,4-D in Laboratory and Solar Pilot-Plant Reactors

A theoretical and experimental study of a pilot-plant solar reactor for the photo-Fenton degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution is presented. Initially, a kinetic model is proposed to obtain the reaction rates of 2,4-D, the main intermediate (2,4-dichlorophenol), and the hydrogen peroxide. The kinetic study was performed in a well-stirred tank laboratory reactor. The effects of ferric salt initial concentrations, hydrogen peroxide to 2,4-D initial concentration ratios, reaction temperatures, and radiation levels are studied. The proposed kinetic model and the experimental data are used to estimate the kinetic parameters, applying a nonlinear regression procedure. Afterward,the kinetic model is used to predict the reactant concentrations during the photo-Fenton degradation in a pilot-plant solar reactor designed to capture the UV/visible/IR solar radiation. The solar reactor was able to reach a complete degradation of the 2,4-D and 2,4-dichlorophenol after 60 min, and a total organic carbon conversion of 98.9% after 210 min.Fil: Conte, Leandro Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; ArgentinaFil: Farias, Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; ArgentinaFil: Albizzati, Enrique D.. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; Argentin