title: Decolourization of Rhodamine B: A swirling jet-induced cavitation combined with NaOCl.
abstract: A hydrodynamic cavitation reactor (Ecowirl) based on swirling jet-induced cavitation has been used in order to allow the degradation of a waste dye aqueous solution (Rhodamine B, RhB). Cavitation generated by Ecowirl reactor was directly compared with cavitation generated by using multiple hole orifice plates. The effects of operating conditions and parameters such as pressure, pH of dye solution, initial concentration of RhB and geometry of the cavitating devices on the degradation rate of RhB were discussed. In similar operative conditions, higher extents of degradation (ED) were obtained using Ecowirl reactor rather than orifice plate. An increase in the ED from 8.6% to 14.7% was observed moving from hole orifice plates to Ecowirl reactor. Intensification in ED of RhB by using hydrodynamic cavitation in presence of NaOCl as additive has been studied. It was found that the decolourization was most efficient for the combination of hydrodynamic cavitation and chemical oxidation as compared to chemical oxidation and hydrodynamic cavitation alone. The value of ED of 83.4% was reached in 37min using Ecowirl combined with NaOCl (4.0mgL(-1)) as compared to the 100min needed by only mixing NaOCl at the same concentration. At last, the energetic consumptions of the cavitation devices have been evaluated. Increasing the ED and reducing the treatment time, Ecowirl reactor resulted to be more energy efficient as compared to hole orifice plates, Venturi and other swirling jet-induced cavitation devices, as reported in literature.
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy. Electronic address: giuseppe.mancuso@unitn.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancuso
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy. Electronic address: michela.langone@unitn.it.
authors.forename: Michela
authors.initials: M
authors.lastname: Langone
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy. Electronic address: laezza.marco@gmail.com.
authors.forename: Marco
authors.initials: M
authors.lastname: Laezza
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy. Electronic address: gianni.andreottola@unitn.it.
authors.forename: Gianni
authors.initials: G
authors.lastname: Andreottola
keywords: Energy efficient; Rhodamine B degradation; Sodium hypochlorite; Swirling jet-induced cavitation; Synergetic effect