Activation of sulfite autoxidation with CuFeO prepared by MOF-templated method for abatement of organic contaminants.

Copper ferrite (denoted as CuFeO), prepared via a complexation reaction to obtain bimetal-organic frameworks (Cu/Fe bi-MOFs), followed by a combustion process to remove the MOF template, is employed as a heterogeneous activator to promote sulfite autoxidation for the removal of organic contaminants. At pH 8.0, more than 80% of the recalcitrant organic contaminant iohexol (10 μM) can be removed within 2 min by the activation of sulfite (500 μM) with CuFeO (0.1 g L). CuFeO exhibits more pronounced catalytic activity in accelerating sulfite autoxidation for iohexol abatement compared to that fabricated by hydrothermal and sol-gel combustion methods. Radical quenching studies suggest that the sulfate radical (SO) is the main reactive species responsible for iohexol abatement. The performance of CuFeO/sulfite for iohexol abatement can be affected by several critical influencing factors, including the solution pH and the presence of humic acid, Cl, and HCO. The effect of the ionic strength and the results of the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis indicate that sulfite autoxidation in the presence of CuFeO involves an inner-sphere interaction with the surface Cu(II) sites of CuFeO. X-ray photoelectron spectroscopy (XPS) characterization suggests that the surface Cu(II)-Cu(I)-Cu(II) redox cycle is responsible for efficient SO production from sulfite. Overall, CuFeO can be considered an alternative activator for sulfite autoxidation for potential application in the treatment of organic-contaminated water.