كيميا نديري

Advanced oxidation processes (AOPs), founded on the generation of highly reactive species such as hydroxyl radicals, are among the most promising current techniques for the degradation of persistent organic pollutants. Hydrodynamic cavitation, through the intense physical conditions generated by the vapor bubble collapse, offers an appropriate environment for the formation of such reactive species. This study was designed an‎d executed to compare the performance of hybrid systems consisting of hydrodynamic cavitation an‎d advanced oxidation processes for the removal of the recalcitrant antibiotic ofloxacin. Optimization of the conventional Venturi using the response surface methodology (RSM) an‎d CFD simulation established the optimum dimensions as an 80° convergence angle, an 8° divergence angle, an‎d a 4.65 mm throat length. Based on these findings, an optimized tan‎dem Venturi with internal convergence angle 40°, internal divergence angle 6°, an‎d throat diameters 4 mm an‎d 8 mm was created, an‎d it showed 28% enhancement in the formation of cavitation bubbles an‎d enlargement of the cavitation zone compared to the conventional Venturi. For the eva‎luation of chemical efficiency, synergistic effects of different chlorinated oxidants—chloramine-T, sodium perchlorate, an‎d hydrogen peroxide—combined with cavitation were examined. All experiments were conducted using the Box–Behnken design within the framework of RSM, in the range of 0–200 mg.L-1 for each oxidant. Followed by that, combination of chloramine-T, persulfate, an‎d ultraviolet (UV) irradiation in the cavitation system was investigated. Under optimal conditions (100 mg.L-1 chloramine-T, 200 mg.L-1 persulfate, an‎d UV irradiation at 32 W), more than 68% ofloxacin removal was achieved within 60 minutes. Operational parameter analysis indicated that inlet pressure increase up to 3 bar improved the process efficiency, with higher pressures leading to performance loss due to supercavitation. Furthermore, a comparison of three dose intervals of stepwise chloramine-T addition (5, 10, an‎d 20 minutes) indicated that 10-minute intervals provided the highest removal efficiency, with approximately 80.2% degradation. Finally, according to the energy cost ratio (ECR) parameter, the quaternary HC/UV/PS/NH₂Cl-T process, having an ECR value of 0.68, was found to be the most effective an‎d economical arrangement.

كاويتاسيون هيدروديناميكي , اكسيداسيون پيشرفته , اكسيدكننده كلردار , ونتوري

Hydrodynamic Cavitation , Advanced Oxidation Process , Venturi , Cl-based Oxidants

Kimia Nadiri

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