Degradation of 2,4-diclorophenol via coupling zero valent iron and hydrodynamic cavitation for sulfite activation: A turbulence modeling

Abstract

The 2,4-dichlorophenol (2,4-DCP) is an important chemical precursor that can affect human endocrine system and induce pathological symptoms. This research reports the degradation of 2,4-DCP using lab-scale hydrodynamic cavitation (HC) approach, which is considered a green and effective method. To promote the degradation efficiency, the zero-valent iron (Fe-0) as the catalyst for sulfate radical (SO4 center dot-) generation via activation of sulfite (SO32-) salts was simultaneously used. Degradation efficiency was favorable in acidic pH than the alkaline pH due to higher production of active radicals and was dependent on the dose of Fe-0 and SO32-. Under optimal condition, degradation efficiency by Fe-0/HC/sulfite (96.67 +/- 2.90) was considerably enhanced compared to HC alone (45.37 +/- 2.26). Quenching experiments suggested that SO4 center dot-, (OH)-O-center dot, O-1(2), and O-2(center dot-) radicals were involved in the degradation of 2,4-DCP by Fe0/HC/sulfite process, but the dominant role was related to (OH)-O-center dot (70.09 contribution) and SO4 center dot- (29.91 contribution) radicals. From the turbulence model, turbulent pressure at venturi throat decreased from -0.42 MPa to -2.02 MPa by increasing the inlet pressure from 1.0 to 4.0 bar and increase in pressure gradient has intensified bubble collapse due to higher turbulence tension.