New Design Approaches for Ultrasonic Reactors: Degradation of Naphthalene and Phenol in Water

Abstract

This present study has been conducted in order to design new types (single and dual fields) of ultrasonic reactors and to determine the cavitational activity associated with acoustic effects. In particular, this study reports on the effect of different bottom plate inclination angles (60°, 90°, and 120°) on the cavitational efficiency of several different reactors. This efficiency was estimated on the basis of the removal of naphthalene and phenol associated with H₂O₂ production. In each experiment, ultrasonic irradiations of naphthalene and phenol in deionized water with an initial concentration of 2.5 mg L⁻¹ were carried out at a frequency of 580 kHz and with a reaction time of 30 min, an ultrasonic power of 200 W, and an aqueous temperature of 20°C. The concentration of H₂O₂ was also determined in order to investigate the efficacy of different sonochemical reactors for HO• production. It was clearly observed that the HO• production varied depending on the type of reactor. In general, the dual field reactors are more effective for the HO• production than the single field ones. For the dual field reactors, the degradation constants of the compounds followed this order: type D-3 (120°, 14.4 × 10⁻² min⁻¹)  >  type D-1 (60°, 13.7 × 10⁻² min⁻¹)  >  type D-2 (90°, 12.1 × 10⁻² min⁻¹) for naphthalene and type D-3 (120°, 6.8 × 10⁻² min⁻¹)  ≥ type D-1 (60°, 6.7 × 10⁻² min⁻¹)  >  type D-2 (90°, 5.8 × 10⁻² min⁻¹) for phenol. In all the experiments, it was also observed that the degradation of relatively hydrophobic naphthalene was higher than that of phenol.