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The sluggish oxidation kinetics of ferrate (Fe(VI)) at neutral and slightly alkaline pH impedes its rapid abatement of micropollutants in practical application. This work discovers that graphite (GP), a metal-free carbonaceous material, can be a promising material to improve the reactivity of Fe(VI) in the pH range of 7.0 − 9.0. The performance of the GP/Fe(VI) process for sulfamethoxazole (SMX) removal was further evaluated via altering the dosages of Fe(VI), GP, and SMX. Probe analysis and quenching experiments identified Fe(IV) and Fe(V) as the primary active species responsible for the removal of organic compounds in the GP/Fe(VI) system. The detailed activation mechanism of GP is discussed via analyzing the surface chemical changes of GP exposed to Fe(VI). It is found that the carbonyl groups on GP surface execute a critical role in Fe(VI) activation. The GP/Fe(VI) system shows powerful anti-interference ability to environmental background substances. Therefore, the new oxidation process proposed in this work holds a great application prospect for contamination remediation. Finally, we discuss the underlying degradation pathways of SMX by the GP/Fe(VI) system. This study not only develops a promising system for the removal of micropollutants but also provides an in-depth insight into the activation mechanism of metal-free carbonaceous material in Fe(VI) oxidation process. [Display omitted] • GP can improve the oxidation activity of Fe(VI) to eliminate various micropollutants. • Fe(IV) and Fe(V) are the main active oxidants in the GP/Fe(VI) system. • The carbonyl group on GP surface plays a vital role in activating Fe(VI). • The GP/Fe(VI) system shows an excellent environmental adaptability. [ABSTRACT FROM AUTHOR]

The acceleration of Fe(III)/Fe(II) conversion in Fenton systems is the critical route to achieve the long-lasting generation of reactive oxygen species towards the oxidation of refractory contaminants. Here, we found that waste leather derived porous carbon materials (LPC), as a simple and readily available metal-free biochar material, can promote the Fe(III)/H 2 O 2 system to generate hydroxyl radicals (•OH) for oxidizing a broad spectrum of contaminants. Results of characterizations, theoretical calculations, and electrochemical tests show that the surface carbonyl groups of LPC can provide electron for direct Fe(III) reduction. More importantly, the graphitic-N on surface of LPC can enhance the reactivity of Fe(III) for accelerating H 2 O 2 induced Fe(III) reduction. The presence of LPC accelerates the Fe(III)/Fe(II) redox cycle in the Fe(III)/H 2 O 2 system, sustainable Fenton chain reactions is thus initiated for long-lasting generation of hydroxyl radicals without adding Fe(II). The continuous flow mode that couples in-situ Fenton-like oxidation and LPC with excellent adsorption catalytic properties, anti-coexisting substances interference and reusability performance enables efficient, green and sustainable degradation of trace organic pollutants. Therefore, the application of metal-free carbon materials in Fenton-like system can solve its rate-limiting problem, reduce the production of iron sludge, achieve green Fenton chemistry, and facilitate the actual engineering application of economic and ecological methods to efficiently remove trace organic contaminants from actual water sources. [Display omitted] • Waste leather-derived porous carbon can effectively boost Fenton oxidation. • H 2 O 2 can act as an electron donor for green and sustainable Fenton oxidation. • Surface nitrogen of LPC can elevate the reactivity of Fe(III) species. • Sustainable removal of trace refractory organic pollutants was achieved. • Hydroxyl radical induced oxidation pathway of DEP was proposed. [ABSTRACT FROM AUTHOR]