A review of the innovations in metal- and carbon-based catalysts explored for heterogeneous peroxymonosulfate (PMS) activation, with focus on radical vs. non-radical degradation pathways of organic contaminants

In this work, Co3O4 embedded nitrogen and sulfur co-doped porous char (Co3O4@NSC) was prepared after one-pot pyrolysis of N, S in-rich rubber powder (RP) to determine the binding relationship between Co nanoparticles and multiple doped heteroatoms. Results indicated pyridinic N was more easily to coordinate with Co3O4 nanoparticles, forming the pyridinic N-Co binding in Co3O4@NSC, which was the dominant catalytic sites for peroxymonosulfate (PMS) activation. Paracetamol (PCM) degradation was greatly facilitated with Cl- surrounding in Co3O4@NSC/PMS system due to the formation of large amounts of HOCl generated from the direct reaction of Cl- with PMS. The Cl↓ serving as a precursor of HOCl by reacting with PMS can be further strengthened by pyridinic N-Co bindings in Co3O4@NSC than the NSC. As a result, the pyridinic Co-N sites not only acted as the essential catalytic sites for PMS activation, but also accelerated the formation of HOCl at high level of Cl-.

Co3O4 anchored in N, S heteroatom co-doped porous carbons for degradation of organic contaminant: role of pyridinic N-Co binding and high tolerance of chloride

Nonradicals induced degradation of organic pollutants by peroxydisulfate (PDS) and peroxymonosulfate (PMS): Recent advances and perspective

The carbon nanotubes-based materials and their applications for organic pollutant removal: A critical review

New insights into the capture performance and mechanism of hazardous metals Cr3+ and Cd2+ onto an effective layered double hydroxide based material

Nonradical-based advanced oxidation processes for pollutant removal have attracted much attention due to their inherent advantages. Herein we report that magnesium oxides (MgO) in CuOMgO/Fe3O4 not only enhanced the catalytic properties but also switched the free radical peroxymonosulfate (PMS)-activated process into the 1O2 based nonradical process. CuOMgO/Fe3O4 catalyst exhibited consistent performance in a wide pH range from 5.0 to 10.0, and the degradation kinetics were not inhibited by the common free radical scavengers, anions, or natural organic matter. Quantitative structure-activity relationships (QSARs) revealed the relationship between the degradation rate constant of 14 substituted phenols and their conventional descriptor variables (i.e., Hammett constants σ, σ-, σ+), half-wave oxidation potential (E1/2), and pKa values. QSARs together with the kinetic isotopic effect (KIE) recognized the electron transfer as the dominant oxidation process. Characterizations and DFT calculation indicated that the incorporated MgO alters the copper sites to highly oxidized metal centers, offering a more suitable platform for PMS to generate metastable copper intermediates. These highly oxidized metals centers of copper played the key role in producing O2•- after accepting an electron from another PMS molecule, and finally 1O2 as sole reactive species was generated from the direct oxidation of O2•- through thermodynamically feasible reactions.

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Zehua Zeng

Papers

Tuning of Persulfate Activation from a Free Radical to a Nonradical Pathway through the Incorporation of Non-Redox Magnesium Oxide

Facile and novel preparation of 2D-MoS2/carbon nanodots composite with high adsorption efficiency and capacity for dye removal

Facile and scalable preparation of 2D-MoS2/graphene oxide composite for supercapacitor