Economic nanobubbles by RFB and promoted PEF with yolk@double-shell structural photocatalyst for degradation of pharmaceutical pollutants

Abstract

Abstract In this research, the generation of nanobubbles was carried out using a structure of vortex pump based on the relative blockage of flow (without the use of venturi and orifices, which consume a lot of energy to generate nanobubbles), which has made this process economical and commercial. In addition, the use of advanced synthesized nanoreactors with the Yolk@Shell structure, which forms a photoanode by coating the anode electrode and can operate in the visible light range, has highlighted this research work. An in-depth study of the synergistic effect of advanced photoelectrofenton oxidation methods in addition to the hydrodynamic reactor has shown that the intelligent selection of these three types of advanced oxidation methods together has improved the performance of each other and solved their negative aspects, including the use of hydrogen peroxide, divalent iron ion, and the removal of sludge generated by the electrofenton method. The use of hollow cylindrical electrodes allowed adequate loading of the advanced synthesized nanoreactors with Yolk@Shell structure. The investigation of the effects of micro (advanced synthesized nanoreactors with Yolk@Shell structure) and macro (vortex structure based on relative blockage of the flow) processes on the degradation of pharmaceutical pollutants, both separately and in combination, is a focus of this work. At the end, the energy consumption for each of these processes and this system in general was studied, which showed that the operating cost of this combined system according to the energy consumption requirements for the almost complete removal of the pollutant naproxen and the 90% reduction of its chemical oxygen demand is 6530 Rials/L.h (or 0.15525 USD/L.h), which presents this system as an economical method with industrialization capability. The degradability index (DI) of the introduced system under optimal operating conditions was 3.38, which shows that the development of the system based on the combination of advanced oxidation methods is a suitable method used in this research work due to its environmental friendliness, absence of side effluent production, efficiency and high degradation performance, ability to recover the nanocatalyst and consequently economic efficiency.