Carbon nitride nanotubes anchored with Cu(I) triggers peracetic acid activation with visible light for removal of antibiotic contaminants: Probing mechanisms of non-radical pathways and identifying active sites

Harnessing CuCoOX-Modified copper phenylacetylene for enhanced activation of peroxymonosulfate in non-radical sulfisoxazole degradation: Performance, pathways, and mechanisms

The advanced oxidation process utilizing peroxymonosulfate (PMS) represents a promising approach for the treatment of refractory antibiotic compounds in water. However, the unactivated form of PMS shows limited degradation efficiency, necessitating the development of activation strategies to improve catalytic degradation. In this study, a rapid and straightforward solvothermal method was employed to synthesize a CuCoOX-modified phenylacetylene copper catalyst (PhC2Cu), which effectively activates PMS for the degradation of sulfisoxazole (SIZ) in water. The modified catalyst exhibited a catalytic performance approximately 29 times greater than its unmodified counterpart, achieving complete degradation of the target pollutant within 5 min. Additionally, the PhC2Cu/CuCoOX + PMS system successfully degraded nine antibiotics, including sulfonamides, fluoroquinolones, and non-steroidal anti-inflammatory drugs. Notably, the catalytic degradation of pollutants in this system primarily followed a non-radical pathway mediated by singlet oxygen (1O2) and high-valent cobalt-oxygen species (Co(IV)). These active species demonstrated strong anti-interference properties, maintaining stability in the presence of various ions, dissolved organic matter, and natural water matrices. Furthermore, the intermediates and degradation pathways of sulfisoxazole (SIZ) were identified through mass spectrometry analysis. This study not only provides a catalytic strategy for the efficient activation of PMS but also elucidates the non-radical degradation mechanism.

Peroxymonosulfate-assisted photocatalysis system enhanced magnetic Fe3O4@P-C3N4 treatment of tetracycline wastewater: Multi-pathways mediated electrons migration to generate reactive species

Photocatalytic wastewater purification is essential for environmental remediation, but rapid carrier recombination and limited oxidative capacity hinder progress. This study proposes an innovative strategy by integrating homogeneous and heterogeneous electron acceptors into a g-C3N4-based photocatalytic system, significantly enhancing the multipath utilization of photogenerated electrons. A novel Fe3O4@P-C3N4 was developed to activate an advanced peroxymonosulfate-assisted photocatalysis (PAP) system, achieving complete degradation and significant mineralization of tetracycline (TC) in real water environments, outperforming others reported in the last five years. Phytic acid, as a key precursor, modifies the hollow tubular morphology and introduces phosphorus (P) heteroatoms as electronic trapping centers, enhancing the visible light response and carrier separation, thereby promoting the Fe2+/Fe3+ cycle and the formation of reactive species. Density functional theory (DFT) calculations pinpointed TC's vulnerable sites and synergically identified reactive species, revealing almost non-toxic degradation processes. Moreover, the recyclable magnetic Fe3O4@P-C3N4/PAP system demonstrates practical application potential and leaching stability in cyclic and continuous testing. This study offers unique insights into the strategic design of photocatalysts and catalytic environments, potentially advancing practical wastewater remediation.

Efficient activation of peracetic acid by defect-engineered MoO2-x: Oxygen vacancies and surface Mo(Ⅴ)-mediated electron transfer processes

The role of defect regulation of transition metal catalysts in peracetic acid (PAA) activation is equivocal. To reveal the corresponding mechanism, this work provides a high-efficiency and eco-friendly catalyst (MoO2-x) for PAA activation by introducing various degrees of oxygen vacancies on the MoO2 surface. Interestingly, 95.83 % of tetracycline (TC) is rapidly degraded by MoO2-x with rich oxygen vacancies within 20 min via PAA activation, which is superior over that of MoO2-x with poor oxygen vacancies and other typical oxidants (H2O2, SO32-, S2O82-, HSO5-, IO4-). In addition, the defect-regulated MoO2-x exhibits good de-biotoxicity towards TC. Moreover, MoO2-x shows satisfactory purification of various contaminants and actual pharma wastewater. Active species identification suggests that the electron transfer process triggered by the active complex (MoO2-x -PAA*) of PAA bonded on the MoO2-x surface plays the dominant role in TC degradation, while •OH plays a minor role. Mechanism analysis reveals that oxygen vacancies play an indispensable role in accelerating the adsorption and complexation of PAA as well as improving electrical conductivity. Active site analysis demonstrates that Mo(Ⅴ) on the MoO2-x surface acts as an electron shuttle and is the main PAA activation site. This work provides a new approach into the application of MoO2 in hospital wastewater purification via defect engineering.

Selective oxidation decontamination in cobalt molybdate activated Fenton-like oxidation via synergic effect of cobalt and molybdenum

In this study, cobalt molybdate (CoMoO4) activated peracetic acid (PAA) was developed for water purification. CoMoO4/PAA system could remove 95% SMX with pseudo-first-order reaction rate constant of 0.15410 min-1, which was much higher than CoFe2O4/PAA, FeMoO4/PAA, and CoMoO4/persulfate systems. CoMoO4/PAA system follows a non-radical species pathway dominated by the high-valent cobalt (Co(IV)), and CH3C(O)OO• shows a minor contribution to decontamination. Density functional theory (DFT) calculation indicates that the generation of Co(IV) is thermodynamically more favorable than CH3C(O)OO• generation. The abundant Co(IV) generation was attributed to the special structure of CoMoO4 and effect of molybdenum on redox cycle of Co(II)/Co(III). DFT calculation showed that the atoms of SMX with higher ƒ0 and ƒ- values are the main attack sites, which are in accordance with the results of degradation byproducts. CoMoO4/PAA system can effectively reduce biological toxicity after the reaction. Benefiting from the selective of Co(IV) and CH3C(O)OO•, the established CoMoO4/PAA system exhibits excellent anti-interference capacity and satisfactory decontamination performance under actual water conditions. Furthermore, the system was capable of good potential practical application for efficient removal of various organics and favorable reuse. Overall, this study provides a new strategy by CoMoO4 activated PAA for decontamination with high efficiency, high selectivity and favorable anti-interference.

Progress on mechanism and efficacy of heterogeneous photocatalysis coupled oxidant activation as an advanced oxidation process for water decontamination

The rising debate on the dilemma of photocatalytic water treatment technologies has driven researchers to revisit its prospects in water decontamination. Nowadays, heterogeneous photocatalysis coupled oxidant activation techniques are intensively studied due to their dual advantages of high mineralization and high oxidation efficiency in pollutant degradation. This paved a new way for the development of solar-driven oxidation technologies. Previous reviews focused on the advances in one specific coupling technique, such as photocatalytic persulfate activation and photocatalytic ozonation, but lack a consolidated understanding of the synergy between photocatalytic oxidation and oxidant activation. The synergy involves the migration of photogenerated carriers, radical reaction, and the increase in oxidation rate and mineralization. This review systematically summarizes the fundamentals of activation mechanism, advanced characterization techniques and synergistic effects of coupling techniques for water decontamination. Besides, specific cases that lead researchers astray in revealing mechanisms and assessing synergy are critically discussed. Finally, the prospects and challenges are put forward to further deepen the research on heterogeneous photocatalytic activation of oxidants. This work provides a consolidated view of the existing heterogeneous photocatalysis coupled oxidant activation techniques and inspires researchers to develop more promising solar-driven technologies for water decontamination.