Highly efficient manganese-based catalysts for contaminant oxidation in water has drawn increasing attention in recent years. However, the activation of peroxymonosulfate (PMS) as the oxidant was based on the formation of reactive radicals in most cases. In this study, iron doped manganese oxide (Mn3O4) at a Fe/Mn ratio of 1/5 was synthesized and applied to activate PMS for contaminant degradation. The results showed that iron was successfully incorporated into the framework of Mn3O4 and enhanced PMS activation. Higher degradation efficiency was found at pH lower than the pKa of the organic compounds and PMS which favored the adsorption at the catalyst surface. Methanol and tert-Butyl alcohol as radical scavengers only had marginal inhibition effects, which was likely due to less adsorption at the catalyst surface. The notable inhibition effects of furfuryl alcohol and 1,4-benzoquinone as the scavengers of singlet oxygen (1O2) and superoxide (O2−) indicated potential roles of 1O2 and O2−. However, no corresponding signals were observed on electron paramagnetic resonance spectra. Further comparison with the photoexcited methylene blue system as a classical 1O2 generation system suggested different oxidation patterns. Direct electron transfer from the organic substrate to PMS via the catalyst was therefore proposed as the main mechanism for this system. An electrochemical cell pair (Galvanic cells) with two catalyst-coated graphite electrodes was developed where BPA and PMS were present in two separate cells. A strong and continuous current was observed from the PMS cell to the BPA cell accompanied with BPA degradation. Overall, this study developed an efficient Mn-based catalyst for efficient contaminant degradation.

Direct electron transfer based peroxymonosulfate activation by iron doped manganese oxide (Mn3O4): New approach for water treatment

2019 Fall National Meeting

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