Siberian Federal University

The present study is the first report on applying combination of low-pressure hydrodynamic cavitation and high-frequency ultrasound in the megahertz range (1.7 MHz) in a single reactor system (hydrodynamic-acoustic cavitation – HAC) in sulfate radical-based advanced oxidation processes (SR- AOPs) for degrading bisphenol A (BPA). A comparative evaluation of individual, combined and hybrid oxidation systems has been provided. The degradation efficiency of the target compound increases in the following order: AC < HC < HAC < HC/PS ≈ AC/PS < HAC/PS<< HAC/PS/Fe2+. The combination of two types of persulfate (PS) activation (cavitation and Fe2+ ions) in the hybrid oxidation system HAC/PS/ Fe2+ shows significant synergistic effects due to faster and more efficient generation of reactive oxygen species (ROS) from PS. Only in hybrid HAC/PS/Fe2+ system, along with the almost complete oxidation of BPA (97 %), a quite high mineralization (up to 60 %) in terms of total organic carbon (TOC) decay has been achieved without accumulation of toxic intermediates. Radical quenching tests showed that both SO4• – and HO• radicals are involved in the hybrid HAC/PS/Fe2+ system, with HO• being more dominant. The effects of pH, inlet pressure, Fe2+ and PS concentrations were studied and discussed. The influence of natural organic matter (NOM) and coexisting inorganic anions (SO42-, Cl- and HCO3-) were also examined, but only Cl- (10 mM) had a promoting effect on BPA degradation. This study demonstrates the great potential of hybrid HAC/PS/Fe2+ process for effective degradation of emerging organic contaminants with good scale-up capabilities