Effective inactivation of Escherichia coli in aqueous solution by activated carbon-supported FeOOH as heterogeneous Fenton catalyst with high stability and reusability

Activated carbon-supported goethite (α-FeOOH@AC) was prepared by a simple impregnation method to catalyze hydrogen peroxide (H₂O₂) for effective inactivation of Escherichia coli (E. coli) with α-FeOOH and AC as controls. As expected, α-FeOOH particles were uniformly distributed on AC surfaces and surface-bound Fe(III) was partially converted to Fe(II) by structural hydroxyl groups of AC. The resultant Fe(II) catalyzed H₂O₂ to generate hydroxyl radicals (·OH) for effective E. coli inactivation by destroying its membrane and intracellular substances. The α-FeOOH@AC-H₂O₂ system therefore achieved an effective inactivation efficiency of 4.5 log, which was much higher than 1.6 log of the α-FeOOH-H₂O₂ system and 1.9 log of the AC-H₂O₂ system. Besides, due to the cycle of Fe(III)/Fe(II) redox on AC surface during reaction, high inactivation efficiency and low leaching iron concentration of 0.29 mg/L could be achieved at neutral condition. In addition, the α-FeOOH@AC showed excellent stability and reusability, and the used α-FeOOH@AC could be refreshed by eluting surface-bound iron oxides and reloading α-FeOOH particles with the above impregnation method. Our study demonstrated that α-FeOOH@AC is an effective and stable heterogeneous Fenton catalyst for the inactivation of E. coli in surface water treatment.