Hydroxyl radical streaming from molecular oxygen activation by β-FeC2O4·2H2O for efficiently degrading Microcystin-LR

In this study, β-FeC 2 O 4 ·2H 2 O was employed to activate molecular oxygen for the generation of abundant hydroxyl radicals (•OH) for efficient degradation of toxic Microcystin-LR (MC-LR) at ambient conditions. Specifically, dioxygen is selectively reduced to H 2 O 2 through a two-electron transfer pathway on the (0 2 2) facet of β-FeC 2 O 4 ·2H 2 O crystals, and then H 2 O 2 reacts with Fe(II) to form •OH. The electron utilization efficiency of β-FeC 2 O 4 ·2H 2 O toward •OH is high up to 87.7%, ensuring the formation of a sustainable •OH stream. In addition, the Fe 3+ generated from β-FeC 2 O 4 ·2H 2 O oxygenation coordinates with oxalate to form soluble [Fe 3+ -(C 2 O 4 2- ) 2 ] - complex, avoiding the formation of passivated Fe(III) oxide/hydroxide shell on β-FeC 2 O 4 ·2H 2 O and enabling the long durability of β-FeC 2 O 4 ·2H 2 O. When MC-LR is oxidized, the •OH primarily attacks the conjugated dienes (the essential group for the hepatotoxicity) in the Adda side chain of MC-LR. The toxicity assessment by PP2A test shows that the oxidation products are not hepatotoxins. As β-FeC 2 O 4 ·2H 2 O governing water treatment is easily manipulated, cost-effective, highly effectual, environmentally benign as well, it is promising to eliminate MC-LR contamination in natural waters and can be applied in large scale. • MC-LR can be efficiently degraded by β-FeC 2 O 4 ·2H 2 O under aerobic condition. • Electron utilization efficiency of β-FeC 2 O 4 ·2H 2 O for •OH generation is 87.7%. • β-FeC 2 O 4 ·2H 2 O possesses surface structure-dependent O 2 activation property. • Hepatotoxicity of MC-LR was efficiently decreased by the β-FeC 2 O 4 ·2H 2 O/O 2 system. • β-FeC 2 O 4 ·2H 2 O has good durability in ROS generation and MC-LR removal.