title: Sonochemical and sonophotocatalytic degradation of malachite green: the effect of carbon tetrachloride on reaction rates.
abstract: A comparative study between the sonolytic, photocatalytic and sonophotocatalytic oxidation processes of aqueous solutions of malachite green was carried out in the presence of carbon tetrachloride, under a low power ultrasonic field (<15 W) and using titanium dioxide as a photocatalyst. The effect of a number of parameters such as ultrasonic intensity, TiO2 crystalline structure and the presence of CCl4 were studied using an inexpensive reactor. Enhanced rates of sonolytic degradation of malachite green in the presence of CCl4 were demonstrated. On the other hand, the simultaneous use of sonolysis and photocatalysis in the presence of CCl4 does not improve the degradation rate of malachite green in comparison with the one obtained using only sonolysis, but it makes possible a faster oxidative degradation of some reaction intermediaries. Finally, in air saturated solutions both processes, the sonolytic and the photocatalytic one, follow a first-order rate law.
authors.affiliation: Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Cra 30 # 45-03, Edificio 451, Bogotá, Colombia.
authors.forename: Néstor Javier
authors.initials: NJ
authors.lastname: Bejarano-Pérez
authors.affiliation: Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Cra 30 # 45-03, Edificio 451, Bogotá, Colombia. Electronic address: mfsuarezh@unal.edu.co.
authors.forename: Marco Fidel
authors.initials: MF
authors.lastname: Suárez-Herrera
mesh_terms: D002251:Carbon Tetrachloride / Q000737:chemistry*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D010777:Photochemistry; D011193:Potassium Iodide / Q000737:chemistry; D012394:Rosaniline Dyes / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D014465:Ultrasonics; D014867:Water
chemical_list: D012394:Rosaniline Dyes; D012996:Solutions; D014867:Water; C005095:malachite green; D011193:Potassium Iodide; D002251:Carbon Tetrachloride