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

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 (Fe⁰) as the catalyst for sulfate radical (SO₄^•-) generation via activation of sulfite (SO₃^2-) 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 Fe⁰ and SO₃^2-. Under optimal condition, degradation efficiency by Fe⁰/HC/sulfite (96.67 ± 2.90%) was considerably enhanced compared to HC alone (45.37 ± 2.26%). Quenching experiments suggested that SO₄^•-, ^•OH, ¹O₂, and O₂^•- radicals were involved in the degradation of 2,4-DCP by Fe⁰/HC/sulfite process, but the dominant role was related to ^•OH (70.09% contribution) and SO₄^•- (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.