Heterogeneous Electro-Fenton system for efficient degradation of 2,4-DCP: Dual activation of O2 for H2O2 generation and oxygen-defect cobalt ferrite catalysts

In this study, an innovative heterogeneous Electro-Fenton system (R-FPE system) was designed for degrading bio-refractory 2,4-dichlomphenol (2,4-DCP). Fe rod and polymer-carbon composite (PCC) electrodes were employed as anode and cathode, respectively; and sodium disilicate (SD) solution as electrolyte could coordinate with the electrogenerated ferrous iron (Fe(II)). Dual activation of O-2 at near-neutral pH, i.e., both the electrochemical and chemical activation, accounted for the on-site generation of H2O2. As the heterogeneous catalyst, the reduced CoFe2O4 (R-CoFe2O4) displayed an excellent H2O2 decomposition activity, because it had larger surface area, smaller particle size and more surface oxygen defects than pristine CoFe2O4 (P-CoFe2O4). The radical scavenging and electron paramagnetic resonance tests revealed that hydroxyl radicals were the dominant species to destroy 2,4-DCP. The optimal parameters for 2,4-DCP degradation were 10 mM SD at pH 7.5, 10 mA electrical current, and 0.4 g/L R-CoFe2O4. The magnetism of R-CoFe2O4 enabled a magnetic separation process for its recovery, and a followed CaO-coagulation stage could effectively remove the remaining dissolved ferric iron in the reaction solution. According to this study, a process consisting of the oxidation in R-FPE system, the magnetic separation of R-CoFe2O4 catalyst and the CaO-coagulation is prospectively proposed for treating intractable organic wastewater.

Automated summary

An innovative heterogeneous Electro-Fenton system (R-FPE system) was designed for degrading bio-refractory 2,4-dichlomphenol (2,4-DCP). Fe rod and polymer-carbon composite (PCC) electrodes were employed as anode and cathode, respectively; and reduced CoFe2O4 (R-CoFe2O4) displayed an excellent H2O2 decomposition activity. The process consisting of the oxidation in R-FPE system, the magnetic separation of R-CoFe2O4 catalyst and the CaO-coagulation is prospectively proposed for treating intractable organic wastewater.