Efficient degradation of ibuprofen by Co/Fe@CNFs catalyst in the presence of peroxymonosulfate and persulfate: Characterization, performance, and mechanism comparison

An aptamerelectrochemical sensor based on functional carbon nanofibers for tetracycline determination

Fe-Co@CNF was synthesized by electrospinning technology, and AuNPs was loaded onto Fe-Co@CNF by in-situ reduction to obtain Fe-Co@CNF@AuNPs composite material, which was used as the working electrode based on Au-S bond cooperation. The tetracycline electrochemical sensing interface Fe-Co@CNF@AuNPs@Apt was constructed by connecting mercaptoylated tetracycline (TC) aptamers on Fe-Co@CNF@AuNPs surface. The morphology and composition of Fe-Co@CNF@AuNPs composites were characterized by SEM, TEM, EDS, XRD and XPS, and the electrochemical properties of tetracycline were evaluated by CV and DPV. The results showed that the addition of Fe and Co did not destroy the structure of the original carbon nanofibers, and their synergistic effect enhanced the electrocatalytic performance, effective electrode area and electron transfer ability of carbon nanofibers. AuNPs are evenly distributed over the fibers, which effectively improves the electrical conductivity of the material. Under the optimal conditions, the theoretical detection limit of tetracycline was 0.213 nM, and the linear detection range was 5.12-10 mM, which could successfully detect tetracycline in milk.

Highly effective degradation of ibuprofen by alkaline metal-doped copper oxides via peroxymonosulfate activation: Mechanisms, degradation pathway and toxicity assessments

Redox ratios of Cu2+/Cu+ and adsorbed oxygen species (Oads) have shown great activity toward radical generation by activating peroxymonosulfate (PMS). Herein, different alkaline metal oxides (CaO, MgO and BaO) and various amounts of CaO are incorporated into CuO, which could tune the main active sites of redox ratios of Cu2+/Cu+ and Oads. The results show that CaO-CuO-5% exhibits the outstanding performance of PMS activation toward ibuprofen (IBF) degradation with excellent kinetics (k = 0.812 min-1). The X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculation show that the CaO-CuO-5% has the higher electron density with superior electron transfer ability and lower PMS adsorption energy. Based on radical scavengers and electron paramagnetic resonance spectrometer (EPR), a nonradical process is proposed to play the dominant role. The degradation pathway and the corresponding toxicity of degraded intermediates with residue PMS after reaction is evaluated by LC-MS/MS and bioassay experiments, indicating the lower antagonistic influence on human hormone receptors after advanced oxidation process. Mitigation of the Cu leaching with cyclic stability can be achieved. This study provides a facile method to optimize high-performance catalysts to activate PMS and offer practical environmental applications in the remediation of emerging contaminants.

Facile synthesis of NaA zeolite supported Co2Fe1 for highly efficient degradation of Acid Orange 7 by activation of peroxymonosulfate

The development of heterogeneous Co-based catalysts with an effective combination mode of Co/Fe and supporter, a facile synthetic method, and a low treatment cost is an important environment challenge for azo dyes degradation by peroxymonosulfate (PMS) activation. In this study, NaA zeolite supported CoxFey with various molar ratio of Fe/Si and Co/Fe was synthesized by a facile hydrothermal process, and used to activate PMS for Acid Orange 7 (AO7) degradation. NaA zeolite supported Co2Fe1 with the Fe/Si molar ratio of 1:10 showed superior catalytic performance compared with other NaA zeolite supported CoxFey. In a system containing 0.6 g/L catalysts, 4 mM PMS, pH 5 and T = 30℃, 95.8% AO7 and 79.1% COD conversion could be achieved at 20 and 60 min, respectively, and the first order kinetic rate constant reached 0.14795 min-1. Moreover, NaA zeolite supported Co2Fe1/PMS system exhibited excellent catalytic effect in a wide pH range of 3-9. Temperature had an obvious effect on AO7 degradation, and the activation energy was 31.36 kJ/mol. HCO3- demonstrated an obvious depression on AO7 degradation, while Cl-, SO42- and H2PO4- had a relatively poor impact. Quenching experiments showed that both sulfate radicals ([Formula: see text]) and hydroxyl radicals (·OH) were generated in the PMS reaction system, and the [Formula: see text] was the dominant active radical. During 3 cycles experiments, an acceptable AO7 conversion ratio (91.8%) within 30 min arrived, suggesting the good stability of NaA zeolite supported Co2Fe1.

Activation of peroxymonosulfate for degrading ibuprofen via single atom Cu anchored by carbon skeleton and chlorine atom: The radical and non-radical pathways

Single atomic Cu catalysts (SACs Cu@C) anchored by carbon skeleton and chlorine atom was synthesized by hydrolyzing Cu-MOFs and then pickled by aqua-regia to remove Cu nanoparticles (NPs Cu). Comparative characterizations revealed that SACs Cu@C was a hierarchically porous nanostructure and Cu dispersed uniformly throughout the carbon skeletons. With less active components, SACs Cu@C behaved better in activating PMS over NPs Cu@C on ibuprofen removal (91.3 % versus 30.2 % in 30 min). Two Cu coordination environments were found by EXAF and DFT calculation, including four-coordinated Cu with 4C atoms and six-coordinated Cu with 4Cu and 2Cl atoms. The obvious interfacial electron delivery between PMS and SACs Cu@C was found, which was enhanced by Cl atom. Cu(I)/Cu(II) redox cycle would donate electron to peroxy bond of PMS for generating OH, SO₄^- and O₂^-. But electron transferred in opposite direction when PMS bonded to Cu atom through its terminal oxygen atom in sulfate, which formed ¹O₂. IBP degradation proceeded through both radical and non-radical route. IBP degradation was inhibited with the presence of TBA, methanol and furfuryl alcohol but accelerated by p-BQ, which could accelerate OH generation. Two degradation pathways were deducted. This study provided a new insight into catalysts designed for PMS activation.

Efficient Activation of Peroxymonosulfate by Cobalt Supported Used Resin Based Carbon Ball Catalyst for the Degradation of Ibuprofen

The extensive use of ibuprofen (IBU) and other pharmaceuticals and personal care products (PPCPs) causes them widely to exist in nature and be frequently detected in water bodies. Advanced catalytic oxidation processes (AOPs) are often used as an efficient way to degrade them, and the research on heterogeneous catalysts has become a hot spot in the field of AOPs. Among transitional metal-based catalysts, metal cobalt has been proved to be an effective element in activating peroxymonosulfate (PMS) to produce strong oxidizing components. In this study, the used D001 resin served as the matrix material and through simple impregnation and calcination, cobalt was successfully fixed on the carbon ball in the form of cobalt sulfide. When the catalyst was used to activate persulfate to degrade IBU, it was found that under certain reaction conditions, the degradation rate in one hour could exceed 70%, which was far higher than that of PMS and resin carbon balls alone. Here, we discussed the effects of catalyst loading, PMS concentration, pH value and temperature on IBU degradation. Through quenching experiments, it was found that SO4− and ·OH played a major role in the degradation process. The material has the advantages of simple preparation, low cost and convenient recovery, as well as realizing the purpose of reuse and degrading organic pollutants efficiently.