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

Abstract

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.