FeS as excellent co-activator driving nano calcium peroxide oxidation for contaminants degradation: Performance and mechanisms

Mechanistic insights into fluoranthene degradation: Activation of peroxymonosulfate by mackinawite and pyrite in aqueous solution and soil slurry

The slow regeneration of Fe(II) in conventional Fenton and Fenton-like systems poses significant limitations for sustained and continuous generation of reactive oxygen species (ROS), which is critical for effective pollutant degradation. This study investigates the use of iron sulfide minerals-specifically, mackinawite (FeS) and pyrite (FeS2)-as both activators and reductants in peroxymonosulfate (PMS)-based Fenton-like systems to enhance Fe(II) regeneration and improve pollutant degradation efficiency. Results demonstrate that over 90 % of fluoranthene (FLT) was degraded within 60 min using the PMS/FeS and PMS/FeS2 systems. Reactive species including SO4-•, HO•, and 1O2 were generated in both systems, with SO4-• playing a primary role in FLT degradation, while 1O2 contributed partially to the process. Both FeS and FeS2 maintained structural stability during PMS activation, with surface Fe(II) oxidized to Fe(III) and reductive sulfur species (S2- in FeS and S22- in FeS2) facilitating the Fe(III)/Fe(II) cycle before ultimately converting to SO42-. These systems demonstrated robust performance across diverse water matrices, achieving excellent FLT degradation in actual groundwater and soil slurry, underscoring the promising application potential of PMS/FeS and PMS/FeS2 systems for remediating FLT-contaminated environments.

Waste control by waste: A new approach for antibiotic removal and metal reuse from livestock wastewater using ascorbic acid-enhanced CaO2/Cu(II) system

Aiming at the coexistence of antibiotics and Cu(II) in livestock wastewater, a novelty strategy for the simultaneous removal of antibiotics and Cu ions by in-situ utilization of Cu(II) (i.e., CP/Cu(II) and CP/Cu(II)/ascorbic acid (AA) systems) was proposed. The removal rate of florfenicol (FF) in the CP/Cu(II)/AA system was 6.9 times higher than that of the CP/Cu(II) system. CP/Cu(II)/AA system was also effective in removing antibiotics from real livestock tailwater. Simultaneously, the removal of Cu ions in CP/Cu(II) and CP/Cu(II)/AA systems could reach 54.5 % and 15.7 %, respectively. The added AA could significantly enhance the antibiotics degradation but inhibit the Cu ions removal. HO•, O2•-, Cu(III), and •C-R were detected in the CP/Cu(II)/AA system, in which HO• was confirmed as the predominant contributor for FF degradation, and Cu(III) and •C-R also participated in FF elimination. The role of AA could accelerate HO• production and Cu(I)/Cu(II)/Cu(III) cycle, and form •C-R. The degradation products and pathways of FF in the CP/Cu(II)/AA system were proposed and the toxicity of the degradation products was evaluated by the toxicity analysis software (T.E.S.T). The results of this work suggest that without introducing complex catalysts, the feasibility of in-situ utilization of Cu(II) inherently or artificially introduced in livestock wastewater activating CP for antibiotic degradation and Cu ions removal was verified.

Enhanced removal of 1,2-dichloroethane by nanoscale calcium peroxide activation with Fe(III) coupled with different iron sulfides

Fe(II) is of great importance in iron-based advanced oxidation processes. However, traditional methods to maintain Fe(II) concentration, such as the addition of chelating agents or reducing agents, may lead to an increase in chemical oxygen demand of secondary pollution. Therefore, in this study, iron sulfides, namely ferrous sulfide (FeS), pyrite (FeS2), and sulfidated nanoscale zero-valent iron (S-nZVI), were applied for not only the regeneration of Fe(II) but also the direct dissolution of Fe(II). Nanoscale calcium peroxide (nCaO2) was synthesized and used as the oxidant. The removal of 1,2-dichloroethane (1,2-DCA) were significantly promoted from 8.8 to 98.2, 79.2, and 80.8% with the aid of FeS, FeS2, and S-nZVI within 180 min, respectively. The dominant reactive oxygen species were demonstrated and their steady-state concentrations were quantified. Besides, the dechlorination of 1,2-DCA reached 90.4, 69.5, and 83.9% in nCaO2/Fe(III) systems coupled with FeS, FeS2, and S-nZVI, respectively. All three systems had high tolerance to the complex water conditions, of which FeS-enhanced nCaO2/Fe(III) system displayed the best performance, which could be recommended to put into practice for the remediation of 1,2-DCA contaminated groundwater.

Research progress of procyanidins in repairing cartilage injury after anterior cruciate ligament tear

Anterior cruciate ligament (ACL) tear is a common sports-related injury, and cartilage injury always emerges as a serious complication following ACL tear, significantly impacting the physical and psychological well-being of affected individuals. Over the years, efforts have been directed toward finding strategies to repair cartilage injury after ACL tear. In recent times, procyanidins, known for their anti-inflammatory and antioxidant properties, have emerged as potential key players in addressing this concern. This article focuses on summarizing the research progress of procyanidins in repairing cartilage injury after ACL tear. It covers the roles, mechanisms, and clinical significance of procyanidins in repairing cartilage injury following ACL tear and explores the future prospects of procyanidins in this domain. This review provides novel insights and hope for the repair of cartilage injury following ACL tear.

Ascorbic acid promoted sulfadimidine degradation in the magnetite-activated persulfate system by facilitating the Fe(III)/Fe(II) cycle

Persulfate (PS) activation technologies were of significant importance to the organic contaminant treatment. In this study, ascorbic acid (AA) was introduced to the traditional PS-activated process by using magnetite (Fe3O4) as the activator; herein, the degradation efficiency of sulfadimidine (SM2) was improved from 30 to 93% within 3 h, and the observed removal rate was about 8.0 times higher than that of the Fe3O4/PS system. These improvements were found to be induced by the added AA because it could reduce the surface Fe(III) to Fe(II) on Fe3O4 and thus facilitate the Fe(III)/Fe(II) cycle, which was conducive to producing reactive oxygen species (ROSs) in the oxidation process during PS activation. Meanwhile, AA could also promote the Fe(III)/Fe(II) cycle in the homogeneous solution, further advancing the PS decomposition for SM2 degradation. The ROS trapping experiments indicated that SM2 removal in the Fe3O4/PS/AA system was attributed to •OH and •SO4-, and •SO4- was the dominant ROS. Moreover, the reusability test experiment revealed that magnetite retained good activity after five cycles in the Fe3O4/AA/PS system. This study provides a promising PS activation technology for efficient organics contaminant treatment.