Enhanced humic acid degradation by Fe3O4/ultrasound-activated peroxymonosulfate : Synergy index, non-radical effect and mechanism

Mechanism of peroxymonosulfate activation by nanoparticle Co@N-C: Experimental investigation and theoretical calculation

The release of organic dyes, such as Rhodamine B (RhB), into industrial wastewater has led to significant issues with color pollution in aquatic environments. Herein, we prepared a cobalt nanoparticles (NPs)-based catalyst with the nitrogen-doped carbon-support (Co@N-C) for effective PMS activation. The Co@N-C/PMS system demonstrated the excellent catalytic activity of Co@N-C for activating PMS, achieving nearly 100% degradation of RhB. Singlet oxygen (1O2) and sulfate radicals (SO4•-) were dominant reactive oxygen species for RhB degradation. Density functional theory (DFT) calculations substantiated that the production of 1O2 commenced with the initial generation of *OH through hydrogen abstraction from PMS, culminating in the direct release of oxygen to form 1O2 (PMS→*OH→O*→1O2). The generation of SO4•- was attributed to electron transfer to PMS from the surface of Co NPs (Co0→Co2+→Co3+) and the C-N shell (Co2+→Co3+). The research findings provided new insights into the development of Co-based heterogeneous catalysis for advanced oxidation of refractory organic pollutants in wastewater treatment.

Sulfur-decorated Fe/C composite synthesized from MIL-88A(Fe) for peroxymonosulfate activation towards tetracycline degradation: Multiple active sites and non-radical pathway dominated mechanism

Peroxymonosulfate (PMS)-mediated advanced oxidation processes gain growing attention in degrading antibiotics (e.g., tetracycline (TC)) in wastewater for their high capacity and relatively low cost, while designing efficient catalysts for PMS activation remains a challenge. In this study, a sulfur-doped Fe/C catalyst (Fe@C-S) synthesized from iron metal-organic frameworks (Fe-MOFs) was developed for PMS activation towards TC removal. Under optimal conditions, the TC removal efficiency of Fe@C-S150/PMS system within 40 min was 91.2%. Meanwhile, the k value for Fe@C-S150/PMS system (0.2038 min-1) was 3.36-fold as high as the S-free Fe@C-based PMS system. Also, Fe@C-S150/PMS system showed high robustness in different water matrices. Further studies found that the TC degradation mechanism was mainly ascribed to the non-radical pathway (1O2 and electron transfer). Fe nanoparticles, S and CO groups on the catalyst all participated in the generation of reactive oxygen species (ROS). Besides, S species could enhance the Fe2+/Fe3+ redox cycle and accelerate the electron transfer process. This work highlights the critical role of S in enhancing the catalytic performance of Fe/C-based catalysts for PMS activation, which would provide meaningful insights into the design of high-performance PMS activators for the sustainable remediation of emerging contaminants-polluted water bodies.

Facet-dependence of Fe3O4 for enhancing osteogenic differentiation of BMSCs

Herein, the facet-dependence of Fe₃O₄ for enhancing osteogenic differentiation is demonstrated for the first time. Experimental results and density functional theory calculations reveal that Fe₃O₄ with exposed (42̄2) facets has greater potential in inducing osteogenic differentiation of stem cells compared with that with exposed (400) facets. Moreover, the mechanisms underlying this phenomenon are revealed.

Mechanistic insights into efficient peroxymonosulfate activation by NiCo layered double hydroxides

The efficient removal of organic refractory pollutants such as dyes and antibiotics in wastewater is crucial for protecting the environment and human health. In this work, a NiCo-layered double hydroxide (NiCo-LDH) with a uniform microspherical, hierarchical structure and a high surface area was successfully synthesized as an effective peroxymonosulfate (PMS) activator for the degradation of various organic dyes and antibiotics. The influence of various parameters on the catalytic activity of the NiCo-LDH was determined. Radical scavenger studies unveiled the major reactive oxygen species (ROSs) generated in the NiCo-LDH/PSM system to be ¹O₂, SO₄^•-, and O₂^•-. Ex-situ X-ray photoelectron spectroscopy (XPS) analysis uncovered the role of Co sites and oxygen vacancy as active sites and revealed the reversible redox properties of NiCo-LDH based on Co²⁺/Co³⁺ cycles. The activation mechanism and Rhodamine B (RhB) degradation pathways were experimentally studied and proposed. The NiCo-LDH is highly versatile, reusable and stable as shown by post-catalysis characterizations. This work shows the excellent catalysis performances and provides insights into the activation mechanism of PMS by NiCo-LDH for organic pollutant remediation.