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Nano Research

Article Title

Nitrogen-doped graphene nanosheets as reactive water purification membranes

Keywords

persulfate activation, nitrogen-doped graphene, phenol oxidation, convective flow, batch system

Abstract

Oxidation of organic pollutants by sulfate radicals produced via activationof persulfate has emerged as a promising advanced oxidation technology toaddress various challenging environmental issues. The development of an effective,environmentally-friendly, metal-free catalyst is the key to this technology.Additionally, a supported catalyst design is more advantageous than conventionalsuspended powder catalysts from the point of view of mass transfer and practicalengineering applications (e.g. post-use separation). In this study, a metal-freeN-doped reduced graphene oxide (N-rGO) catalyst was prepared via a facilehydrothermal method. N-rGO filters were then synthesized by facile vacuumfiltration, such that water can flow through nanochannels within the filters. Variousadvanced characterization techniques were employed to obtain structural andcompositional information of the as-synthesized N-rGO filters. An optimizedphenol oxidative flux of 0.036 ± 0.002 mmol·h–1 was obtained by metal-free catalyticactivation of persulfate at an influent persulfate concentration of 1.0 mmol·L–1and filter weight of 15 mg, while a N-free rGO filter demonstrated negligiblephenol oxidation capability under similar conditions. Compared to a conventionalbatch system, the flow-through design demonstrates obviously enhanced oxidationkinetics (0.036 vs. 0.010 mmol·h–1), mainly due to the liquid flow through thefilter leading to convection-enhanced transfer of the target molecule to the filteractive sites. Overall, the results exemplified the advantages of organic compoundremoval by catalytic activation of persulfate using a metal-free catalyst in flowthroughmode, and demonstrat

Graphical Abstract

Publisher

Tsinghua University Press

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