We demonstrated that riboflavin, one of electron transfer mediators secreted from microbes in natural environments, can significantly affect the reactivity of nanoscale zerovalent iron (nZVI) during the reductive dechlorination of carbon tetrachloride (CT). CT was rapidly degraded by nZVI suspension without riboflavin in 8 h at first cycle (0.556 � 0.044 h-1), while 60% of degradation was observed at third cycle (0.122 � 0.033 h-1). In contrast, addition of riboflavin (1 �M) into nZVI suspension showed lower degradation rate than that without riboflavin at first cycle (0.370 � 0.012 h-1) and faster degradation rate at third cycle (0.663 � 0.005 h-1) indicating that riboflavin can continuously keep the nZVI reactivity alive during CT degradation reaction. However, high amount of riboflavin negatively affected the degradation kinetic of CT during whole reaction cycle due probably to the competitive adsorption of riboflavin on nZVI surface leading to the inhibition of electron transfer between nZVI surface and CT. The measurements of pH, redox potential, particle size, and Fe(II) dissolution were conducted to identify the interaction mechanism between riboflavin and nZVI during CT degradation.

Effect of riboflavin on the reductive degradation of carbon tetrachloride by nanoscale zerovalent iron

245th National Meeting (2013)

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