Degradation System Research Articles

Investigation of amyloid‑β peptide production and clearance pathways in different stages of Alzheimer's disease.

Alzheimer's disease (AD) is an age‑related, progressive decline in cognitive ability. Accumulation and deposition of amyloid‑β (Aβ) is still the best‑known cause of AD that worsens over time. It is unclear whether the increase in Aβ production or the inefficiency of the degradation system causes the accumulation of β‑fibrils during AD development. This research investigated Aβ‑producing and clearance pathways in different stages of AD. For this purpose, patients were categorized into four experimental groups: patients with mild cognitive impairment, patients with moderate cognitive decline, patients with very severe cognitive decline, and healthy patients as control. Levels of Aβ‑40, soluble amyloid precursor protein beta (sAPPβ), matrix metalloproteinase‑9 (MMP‑9), matrix metalloproteinase‑3 (MMP‑3), neprilysin (NEP), angiotensin‑converting enzyme (ACE), and insulin‑degrading enzyme (IDE) were determined by ELISA kits and immunoblotting in serum samples. According to the results, the levels of Aβ‑40 and sAPPβ increased in AD patients from an early stage, and levels were maintained in progressive AD stages. MMP‑9 also increased in the early stage, but its content decreased with disease development. MMP‑3 was significantly higher in the three stages of AD compared to the control patients. However, IDE, NEP, and ACE enzymes as clearing systems decreased in all studied AD samples, with their reductions more remarkable in the middle and late stages. The results showed that multiple Aβ‑degrading enzymes such as NEP and IDE in AD patients decline as AD progresses, while Aβ‑40 and sAPPβ increased from the early stage of the disease. Therefore, it could be concluded that detection of the dementia phase is a critical step for therapeutic strategies.

Coupling defect-inherent built-in electric fields to promote directional charge migration for rapid photocatalytic degradation of levofloxacin

By enhancing the intrinsic built-in electric field (IEF) of the catalyst through defect engineering, and coupling the IEF of the catalyst via an S-type heterojunction structure, a 3-in-1 IEF is formed, which drives the directional migration of electrons and holes, and can effectively improve photocatalytic performance. In this paper, an oxygen vacancy-type Bi2WO6 (Ov-BWO) composite with twin-type Zn0.5Cd0.5S (ZCS) was synthesized to construct an S-scheme heterojunction. The twin structure results in an IEF in ZCS that points from the twin plane Zn to the twin boundary S. The oxygen vacancies, on the other hand, create an internal electric field from Bi and W to O by altering the local charge density. By coupling the IEF of the catalyst through the S-type heterojunction, an enhanced IEF is formed, pointing from the twin plane Zn to the O in Ov-BWO, enabling rapid directional migration of photogenerated charge carriers. Furthermore, potential Levofloxacin (LVFX) intermediates and degradation pathways were found by combining Liquid chromatography-mass spectrometry (LC-MS) data with Density Functional Theory (DFT) simulations. This study systematically elucidates the photocatalytic degradation system, from catalyst design to the degradation process of pollutants, through the analysis of theoretical calculations and experimental results.

Boron nitride quantum dots supported hollow NH2-MIL-125 drive photo-Fenton-PMS system for photocatalytic tetracycline degradation: Contribution of tannic acid etching

NH2-MIL-125(Ti) materials had great potential for photocatalytic applications but had low activity due to exciton effect and narrow absorption range of visible light. The surface oxygen-containing negative functional groups of boron nitride quantum dots (BNQDs) could overcome these defects, but due to the low load capacity, a higher specific surface area of the substrate was usually required. In this paper, a hollow Ti-MOF material was developed by etching technology. The hollow structure formed by tannic acid etching broadened the absorption range of visable light and provided more alternative surfaces for loading BNQDs. The 85.2% of high tetracycline (TC) removal efficiency for the best sample (BNQDs-5@20-Ti-MOF + PMS) was obtained, which was about 56.8 and 1.9 times of the 20-Ti-MOF and BNQDs-5@20-Ti-MOF, respectively. BNQDs-5@20-Ti-MOF + PMS system showed a great TC degradation efficiency in a wide pH range (pH = 5–9). In addition, reaction temperature and the inorganic ions did not show significant inhibition effect for TC removal. Both free radical and non-free radical pathways were involved in the TC degration by BNQDs-5@20-Ti-MOF + PMS system, among which O2•− and 1O2 played the key roles. Interestingly, multiple 1O2 production paths contributed to the high efficiency and stability of BNQDs-5@20-Ti-MOF + PMS system. This study revealed a reasonable combination of Ti-MOF and BNQDs, which provided a new efficient photocatalyst for environmental remediation.

A novel MOF-derived Fe/Ce@NPC-600 floating cathode with massive FeII using in photoelectro-Fenton system for efficient degradation of aqueous tetracycline: Fabrication, performance prediction based on machine learning and mechanism

A MOF-derived carbon/metaloxide composite (Fe/Ce@NPC-600) by doping Ce into NH2-MOF-101(Fe) precursor and simple one-step carbonization was fabricated. Fe/Ce@NPC-600 as a floating cathode was innovatively applied to the solar photoelectro-Fenton (SPEF) process to increase the yield of H2O2 and activate it for degradation tetracycline (TC). The characterizations showed that the presence of Ce greatly increased the content of Fe2+ and photoresponse ability in the material. Thanks to the synergistic effect of Fe and Ce, Fe/Ce@NPC-600 cathode could efficiently degrade TC by 98.2% within 30 min, and the removal rate of total organic carbon (TOC) was 68.2%, and the photoelectric synergistic enhancement factor (fPEF) was 1.4. Besides, based on machine learning, a extreme gradient boosting model was established to predict electrode performance. The degradation mechanism and pathway of TC were also proposed. Our results inspired the application of floating cathodes, MOF-derived materials and artificial intelligence for advanced oxidation processes for efficient removal of emerging contaminants.

Unveiling electron transfer and radical transformation pathways in coupled electrocatalysis and persulfate oxidation reactions for complex pollutant removal

The degradation of multiple organic pollutants in wastewater via advanced oxidation processes might involve different radicals, of which the types and concentrations vary upon interacting with different pollutants. In this study, electrochemical activation of peroxymonosulfate (E/PMS) using advanced activated carbon cloth (ACC) as electrode was applied for simultaneous degradation of mixed pollutants, e.g., metronidazole (MNZ) and p-chloroaniline (PCA). 92.5 % of MNZ and 91.4 % of PCA can be degraded at the cathode and anode at a low current density and PMS concentration, respectively. The rate constants for the simultaneous removal of MNZ and PCA in the E/PMS/MNZ(PCA) system were 118 times and 6 times higher than those in the sole PMS system, and 2.5 times and 1.6 times higher than those in the E/Na2SO4/MNZ(PCA) system, respectively. Different electrochemical characteristics, EPR spectra and radical quenching tests verified that the degradation of MNZ and PCA in the optimal system proceeded primarily through non-radical-dominated oxidation, involving electron transfer and 1O2 effect. The system also exhibited low energy consumption (0.215 kWh/m−3·order−1), broad operational pH range, excellent removal efficiency for water matrix, and low by-products toxicity, indicating its strong potential for practical applications. The ACC, with its super stable, low cost, and electrochemical activity, make it as a promising materials applicable in the E/PMS system for degradation of multiple pollutants. The study further elucidated the mechanism of pollutant interaction with electrode materials in terms of radical and non-radical transformation, providing fundamental insight into the application of this system for treatment of complex wastewater.

Highly energy-efficient degradation of simulated dye wastewater by array type underwater bubble discharge plasma: Key factors identification and degradation pathways

The extensive use of dyes presents a significant safety concern for the reuse of water resources, highlighting the critical need for a rapid and efficient degradation method for dye mixtures in wastewater. This study introduces a degradation system based on an array type underwater bubble discharge plasma specifically designed to treat a dye mixture wastewater containing methylene blue (MB) and methyl violet 2B (MV2B). Analysis of the optical and electrical characteristics reveals that the device experiences minimal temperature increase, with the highest intensity of the band associated with N2 in the emission spectra, and discharges occurring predominantly during the rising and falling edges of a pulse cycle. Experimental results demonstrate that the most effective degradation efficiencies (MB = 94.83%, MV2B = 93.48%) are achieved at an initial dye concentration of 50 mg/L, a power supply frequency of 6 kHz, an air flow rate of 2.5 SLM and an initial electrical conductivity of 50 μS/cm. The degradation of dyes is primarily attributed to the demethylation process of O3(aq) and other species. Toxicity analysis indicates that the plasma degradation process significantly reduces the toxicity of the intermediate products of dyes. This study not only presents a novel approach for treating high concentration mixed dye wastewater, but also provides valuable insights for future research in this area.

COMMD5 counteracts cisplatin-induced nephrotoxicity by maintaining tubular epithelial integrity and autophagy flux.

Oxidative stress mediated by reactive oxygen species (ROS) contributes to apoptosis of tubular epithelial cells (TECs) and renal inflammation during acute kidney injury (AKI). Copper metabolism MURR1 domain-containing 5 [COMMD5/hypertension-related, calcium-regulated gene (HCaRG)] shows strong cytoprotective properties. COMMD5 is highly expressed in proximal tubules (PTs), where it controls cell differentiation. We assessed its role in cisplatin-induced AKI using transgenic mice in which COMMD5 is overexpressed in the PTs. Cisplatin caused the accumulation of damaged mitochondria and cellular waste in PTs, thus increasing the apoptosis of TECs. COMMD5 overexpression effectively protected TECs from cisplatin nephrotoxicity by decreasing intracellular ROS levels, mitochondrial dysfunction, and apoptosis through the preservation of tubular epithelial integrity, thus alleviating morphological and functional kidney damage. Excessive ROS production by hydrogen peroxide led to long-term autophagy activation through an increased burden on the autophagy/lysosome degradation system in TECs, and autophagic elimination of damaged mitochondria and cellular waste was compromised. COMMD5 attenuated oxidative injury by increasing autophagy flux, possibly due to a reduction of intracellular ROS levels through maintained tubular epithelial integrity, which decreased JNK/caspase-3-dependent apoptosis. Meanwhile, COMMD5 inhibition by siRNA reduced the resistance of TECs to cisplatin cytotoxicity, as shown by disrupted tubular epithelial integrity and cell viability. These data indicated that COMMD5 protects TECs from drug-induced oxidative stress and toxicity by maintaining tubular epithelial integrity and autophagy flux and ultimately decreases mitochondrial dysfunction and apoptosis. Increasing COMMD5 content in PTs is proposed as a new protective and therapeutic strategy against AKI.NEW & NOTEWORTHY Oxidative stress overload by drug treatment causes the accumulation of damaged mitochondria that could contribute to tubulopathy. However, effective preventive treatment for drug-induced acute kidney injury remains incompletely understood. Our study showed that copper metabolism MURR1 domain-containing 5 (COMMD5) reduced mitochondrial dysfunction and increased autophagy flux by alleviating reactive oxygen species production through maintaining tubular epithelial integrity when tubular epithelial cells were under oxidative stress, thus ameliorating renal function in cisplatin-treated mice. These results uncover a novel renoprotective mechanism underlying tubular epithelial integrity and autophagy flux.

Integrated fiber paper-based composites enabling photo-Fenton synergistic degradation and switchable adsorption for efficient and multitasking pollutants removal

Single catalytic systems have received wide attention for eradicating pervasive contaminants in water but lack multifunctional integrated biobased capturing and purifying system (bio-CPs). In this work, a universal design of integrated bio-CPs with layered structure driven from fiber filtering paper (FP) was demonstrated for multitasking environmental remediation. Fe-rich composite catalysts (Fe-BiOBr/TiO2) and polyphenol-modified lignin system (PLPR) were herein first developed for the full decoration of FP substrates, achieving the facile construction of layered structure with highly active surface and photocatalytic layer. Profiting from this, a photo-Fenton synergetic degradation system on composites was designed, facilitating a remarkable degradation capability (99.24 % for MEB) and full-time operation ability. Driven by highly enhanced interfacial interactions mediated by polyphenol, this material was capable of efficient capture pollutants (165.29 mg·g-1 for Cr (VI)). And assisted with well-maintained high water flux feature, this bio-CPs that efficient remove pollutants by flowthrough capture were realized, showing the switchable application. Significantly, the convenience of surface deposition and self-assembly supported the potential applications in real system based on extended preparation of such bio-CPs. This work provided a novel and universal strategy to develop the universal and multifunctional integrated bio-CPs to support for large-scale, cost-effective, and sustainable wastewater remediation engineering.

A water stable cobalt-bipyridine based hydrogen bonding double layered network for catalytic degradation of tetracycline

Reaction of Co(NO3)2∙6H2O, 2, 2′-bipyridine (bipy) and 1, 4-benzene dicarboxylic acid (H2BDC) by a two-step hydrothermal process, a stable inorganic-organic hybrid compound, [Co(bipy)(H2O)4]BDC (1), was obtained, which structure was characterized by X-ray single crystal diffraction analysis. Acted as catalyst, its photocatalysis-peroxymonosulfate (PMS) activation for tetracycline (TC) degradation was explored under solar light. The critical experimental factors in tetracycline decomposition were investigated, including the pH, [Co(bipy)(H2O)4]BDC dosage, tetracycline concentration, PMS dose, and temperature. [Co(bipy)(H2O)4]BDC has fast degradation performance, sufficient stability and reusability, that degradation rate were 97.5 % and 88.8 % after five cycles within 60 min. Furthermore, the sulfate radical (SO4•−, superoxide (O2•−), hydroxyl (•OH) free radicals and singlet oxygen (1O2) were confirmed as the key oxidation factors in the 1/PMS/SL system for tetracycline degradation.

CFs-supported La-BiOIO3/Bi2O3 heterostructures via in situ growth strategies for efficiently removing diclofenac: Fermi level modulation, intermediates identification and radical mechanism

The charge transfer efficiency and the recyclability were still the potential factors limiting the widespread application of photocatalysts for pollutant removal. Herein, a novel design perspective for BiOIO3-based S-scheme heterojunction (La-BiOIO3/Bi2O3) with modulated Fermi level and enhanced internal electric field was proposed by in situ liquid-phase growth strategy. Meanwhile, the CFs@La-BiOIO3/Bi2O3 catalysts with high stability and easy recyclability were assembled based on industrial carbon fiber cloths, which can achieve efficiently photocatalytic removal of diclofenac (DCF, 95.5 %, 20 min) and bisphenol A (BPA, 100 %, 30 min) under simulated sunlight irradiation. The photocatalytic degradation rates of DCF were 52.8 and 12.4 times that of pure BiOIO3 and Bi2O3, respectively. The high specific surface area (39.74 m2·g−1) and suitable bandgap structure (2.74 eV) also demonstrated the excellence of the CFs@La-BiOIO3/Bi2O3 degradation system. Verification of heteroatom-driven electron rearrangement and charge migration route in heterostructure was performed through XPS analysis and Mott-Schottky experiments. Gaussian calculations, LC-MS, and toxicity assessments demonstrated that reactive oxygen species (ROS) such as ·O2− and ·OH selectively attacked the electronic groups of DCF and its intermediates, which combined with holes (h+) retained in the valence bands of Bi2O3 to synergistically achieve efficient degradation and detoxification of DCF. Finally, the charge migration mechanism for the photocatalytic elimination of DCF over CFs@La-BiOIO3/Bi2O3 photocatalyst was proposed. Similar studies can be extended to other structures capable of achieving rational Fermi level modulation and synchronous carrier introduction for the remediation of polluted waters, providing novel perspectives for improving photocatalytic driving capacity.

Structural basis for the type I-F Cas8-HNH system

The Cas3 nuclease is utilized by canonical type I CRISPR-Cas systems for processive target DNA degradation, while a newly identified type I-F CRISPR variant employs an HNH nuclease domain from the natural fusion Cas8-HNH protein for precise target cleavage both in vitro and in human cells. Here, we report multiple cryo-electron microscopy structures of the type I-F Cas8-HNH system at different functional states. The Cas8-HNH Cascade complex adopts an overall G-shaped architecture, with the HNH domain occupying the C-terminal helical bundle domain (HB) of the Cas8 protein in canonical type I systems. The Linker region connecting Cas8-NTD and HNH domains adopts a rigid conformation and interacts with the Cas7.6 subunit, enabling the HNH domain to be in a functional position. The full R-loop formation displaces the HNH domain away from the Cas6 subunit, thus activating the target DNA cleavage. Importantly, our results demonstrate that precise target cleavage is dictated by a C-terminal helix of the HNH domain. Together, our work not only delineates the structural basis for target recognition and activation of the type I-F Cas8-HNH system, but also guides further developments leveraging this system for precise DNA editing.

Histamine synthesis and transport are coupled in axon terminals via a dual quality control system

Monoamine neurotransmitters generated by de novo synthesis are rapidly transported and stored into synaptic vesicles at axon terminals. This transport is essential both for sustaining synaptic transmission and for limiting the toxic effects of monoamines. Here, synthesis of the monoamine histamine by histidine decarboxylase (HDC) and subsequent loading of histamine into synaptic vesicles are shown to be physically and functionally coupled within Drosophila photoreceptor terminals. This process requires HDC anchoring to synaptic vesicles via interactions with N-ethylmaleimide-sensitive fusion protein 1 (NSF1). Disassociating HDC from synaptic vesicles disrupts visual synaptic transmission and causes somatic accumulation of histamine, which leads to retinal degeneration. We further identified a proteasome degradation system mediated by the E3 ubiquitin ligase, purity of essence (POE), which clears mislocalized HDC from the soma, thus eliminating the cytotoxic effects of histamine. Taken together, our results reveal a dual mechanism for translocation and degradation of HDC that ensures restriction of histamine synthesis to axonal terminals and at the same time rapid loading into synaptic vesicles. This is crucial for sustaining neurotransmission and protecting against cytotoxic monoamines.

Oxyanion-Sensitive Catalytic Activity of Ni(II)/Oxyanion Systems for Heterogeneous Organic Degradation: Differential Oxidizing Capacity of Ni(III) and Ni(IV) as High-Valent Intermediates.

This study demonstrated that NiO and Ni(OH)2 as Ni(II) catalysts exhibited significant activity for organic oxidation in the presence of various oxyanions, such as hypochlorous acid (HOCl), peroxymonosulfate (PMS), and peroxydisulfate (PDS), which markedly contrasted with Co-based counterparts exclusively activating PMS to yield sulfate radicals. The oxidizing capacity of the Ni catalyst/oxyanion varied depending on the oxyanion type. Ni catalyst/PMS (or HOCl) degraded a broad spectrum of organics, whereas PDS enabled selective phenol oxidation. This stemmed from the differential reactivity of two high-valent Ni intermediates, Ni(III) and Ni(IV). A high similarity with Ni(III)OOH in a substrate-specific reactivity indicated the role of Ni(III) as the primary oxidant of Ni-activated PDS. With the minor progress of redox reactions with radical probes and multiple spectroscopic evidence on moderate Ni(III) accumulation, the significant elimination of non-phenolic contaminants by NiOOH/PMS (or HOCl) suggested the involvement of Ni(IV) in the substrate-insensitive treatment capability of Ni catalyst/PMS (or HOCl). Since the electron-transfer oxidation of organics by high-valent Ni species involved Ni(II) regeneration, the loss of the treatment efficiency of Ni/oxyanion was marginal over multiple catalytic cycles.

Cathodic poised potential stimulated the electron-sensitive C-P lyase pathway in glyphosate biodegradation

Glyphosate, the most widely used herbicide globally, is accumulating in the environment and poses significant potential eco- and bio-toxicity risks. While natural attenuation of glyphosate has been reported, the efficacy varies considerably and the dominant metabolite, aminomethylphosphonic acid (AMPA), is potentially more persistent and toxic. This study investigated the bioelectrochemical system (BES) for glyphosate degradation under anaerobic, reductive conditions. Atomistic simulations using density functional theory (DFT) predicted increased thermodynamic favorability for the non-dominant C-P lyase degradation pathway under external charge, which suppressed AMPA production. Experimental results confirmed that cathodic poised potential (-0.4 V vs. Ag/AgCl) enhanced glyphosate degradation (75 % in BES vs. ∼40 % in the control conditions after 37 days), and lowered the AMPA yield (0.52 mol AMPA yield per mol glyphosate removed in BES vs. 0.77–0.86 mol mol-1 in the control conditions). Geobacter lovleyi was likely the active species driving the C-P lyase pathway, as evidenced by the increase of its relative abundance, the upregulation of its extracellular electron transfer genes (most notably mtr) and the up-regulation of its phnJ and hcp genes (encoding C-P layse and hydroxylamine reductase respectively).

Decreased SREBP2 of the striatal cell relates to disrupted protein degradation in Huntington’s disease

This study delineated the intricate relation between cholesterol metabolism, protein degradation mechanisms, and the pathogenesis of Huntington’s disease (HD). Through investigations using both animal models and cellular systems, we have observed significant alterations in cholesterol levels, particularly in the striatum, which is the primary lesion site in HD. Our findings indicate the dysregulation of cholesterol metabolism-related factors, such as LDLR and SREBP2, in HD, which may contribute to disease progression. Additionally, we uncovered disruptions in protein degradation pathways, including decreased neddylated proteins and dysregulated autophagy, which further exacerbated HD pathology. Moreover, our study highlighted the potential therapeutic implications of targeting these pathways. By restoring cholesterol levels and modulating protein degradation mechanisms, particularly through interventions, such as MLN4924, we observed potential improvements in cellular function, as indicated by the increased BDNF levels. These insights underscore the importance of simultaneously addressing cholesterol metabolism and protein degradation to alleviate HD pathology. Collectively, this study provides a basic understanding of the interplay between the decrease of SREBP2 and the dysfunctional protein degradation system derived from disrupted cholesterol metabolism in HD and HD cells.

Role of Filamin C in Muscle Cells.

Filamin C (FLNC) is a member of a high-molecular weight protein family, which bind actin filaments in the cytoskeleton of various cells. In human genome FLNC is encoded by the FLNC gene located on chromosome7 and is expressed predominantly in striated skeletal and cardiac muscle cells. FilaminC is involved in organization and stabilization of thin actin filaments three-dimensional network in sarcomeres, and is supposed to play a role of mechanosensor transferring mechanical signals to different protein targets. Under mechanical stress FLNC can undergo unfolding that increases the risk of its aggregation. FLNC molecules with an impaired native structure could be eliminated by the BAG3-mediated chaperone-assisted selective autophagy. Mutations in the FLNC gene could be accompanied by the changes in FLNC interaction with its protein partners and could lead to formation of aggregates, which overload the autophagy and proteasome protein degradation systems, thus facilitating development of various pathological processes. Molecular mechanisms of the FLNC-associated congenital disorders, called filaminopathies, remain poorly understood. This review is devoted to analysis of the structure and mechanisms of filamin C function in muscle and heart cells in normal state and in the FLNC-associated pathologies. The presented data summarize the results of research at the molecular, cellular, and tissue levels and allow us to outline promising ways for further investigation of pathogenetic mechanisms in filaminopathies.

Green approach for fabricating hybrids of food waste-derived biochar/zinc oxide for effective degradation of bromothymol blue dye in a photocatalysis/persulfate activation system

This study presents novel composites of biochar (BC) derived from spinach stalks and zinc oxide (ZnO) synthesized from water hyacinth to be used for the first time in a hybrid system for activating persulfate (PS) with photocatalysis for the degradation of bromothymol blue (BTB) dye. The BC/ZnO composites were characterized using innovative techniques. BC/ZnO (2:1) showed the highest photocatalytic performance and BC/ZnO (2:1)@(PS + light) system attained BTB degradation efficiency of 89.47% within 120 min. The optimum operating parameters were determined as an initial BTB concentration of 17.1 mg/L, a catalyst dosage of 0.7 g/L, and a persulfate initial concentration of 8.878 mM, achieving a BTB removal efficiency of 99.34%. The catalyst showed excellent stability over five consecutive runs. Sulfate radicals were the predominant radicals involved in the degradation of BTB. BC/ZnO (2:1)@(PS + light) system could degrade 88.52%, 84.64%, 81.5%, and 77.53% of methylene blue, methyl red, methyl orange, and Congo red, respectively. Further, the BC/ZnO (2:1)@(PS + light) system effectively activated PS to eliminate 97.49% of BTB and 85.12% of dissolved organic carbon in real industrial effluents from the textile industry. The proposed degradation system has the potential to efficiently purify industrial effluents which facilitates the large-scale application of this technique.

Investigation into the Synergistic Effect of the Zinc Peroxide/Peroxymonosulfate Double-Oxidation System for the Efficient Degradation of Tetracycline.

The increasingly severe antibiotic pollution has become one of the most critical issues. In this study, a zinc peroxide/peroxymonosulfate (ZnO2/PMS) double-oxidation system was developed for tetracycline (TC) degradation. A small amount of ZnO2 (10 mg) and PMS (30 mg) could effectively degrade 82.8% of TC (100 mL, 50 mg/L), and the degradation process could be well described by the pseudo-second-order kinetic model. Meanwhile, the ZnO2/PMS double-oxidation system showed high adaptability in terms of reaction temperature (2-40 °C), initial pH value (4-12), common inorganic anions (Cl-, NO3-, SO42- and HCO3-), natural water source and organic pollutant type. The quenching experiment and electron paramagnetic resonance (EPR) characterization results confirmed that the main reactive oxygen species (ROS) was singlet oxygen (1O2). Moreover, three possible pathways of TC degradation were deduced according to the analyses of intermediates. On the basis of comparative characterization and experiment results, a synergistic activation mechanism was further proposed for the ZnO2/PMS double-oxidation system, accounting for the superior degradation performance. The released OH- and H2O2 from ZnO2 could activate PMS to produce major 1O2 and minor superoxide radicals (•O2-), respectively.

Preparation and photocatalytic mechanism of magnetic Ag2S/CoFe1.95Dy0.05O4 Z‐scheme heterojunction

AbstractThe synthesis of high‐efficiency magnetic composite photocatalyst by doping magnetic cobalt ferrite and compounding single semiconductor photocatalyst is a promising strategy to improve the oxidation ability of photocatalytic systems. In this paper, CoFe1.95Dy0.05O4 (CFDO) was prepared by doping Dy element into magnetic CoFe2O4, and Ag2S (AS)/CFDO with high‐efficiency magnetic photocatalyst was synthesized by compounding AS with CFDO as the substrate. The photocatalytic samples were characterized by different advanced characterization methods, and their photocatalytic degradation of methylene blue (MB) was studied. The results show that AS/CFDO exhibits higher visible light response, excellent photogenerated charge separation ability and migration efficiency, and excellent catalytic performance in the catalytic degradation system. The photocatalytic activity of AS/CFDO was the highest, and its photocatalytic degradation kinetic constant K was 2.48 and 1.54 times that of AS and CFDO, respectively. In addition, the catalyst contained in the catalytically contaminated solution can be effectively separated by an external magnetic field to achieve multiple cycles of degradation and recycling. The cyclic degradation experiments showed that AS/CFDO exhibited high degradation stability during the photodegradation process. After the fifth reuse, the degradation efficiency was still more than 88.0%. Finally, the possible photocatalytic mechanism of the samples was discussed. Therefore, this work provides an effective solution for the construction of photocatalysts with high efficiency, magnetic recovery, and cyclic degradation stability and avoids the secondary pollution of catalysts to organic wastewater. It is of great significance to create an environmentally friendly catalytic method for efficient cyclic degradation of organic wastewater.

Synergistic enhancement of singlet oxygen generation in Au and oxygen vacancy co-modified Bi2MoO6 ultrathin nanosheets for efficient ciprofloxacin degradation

Solar-driven molecular oxygen activation (MOA) is crucial for generating reactive oxygen species (ROS) for pollutant degradation, while the low activation efficiency greatly weakens the degradation efficiency. Herein, oxygen vacancies (OVs) and Au nanoparticles are co-introduced into Bi2MoO6 (ABMOH) to enhance the photocatalytic activity of Bi2MoO6 (BMO), thereby promoting MOA efficiency. Density functional theory demonstrates that the introduction of OVs not only improves the molecular oxygen adsorption on BMO, and but also strengthens the O-O bond dissociation of molecular oxygen, which is beneficial to MOA. Meanwhile, the unique localized surface plasmon resonance effect of Au nanoparticles immensely increases the photo-absorption capacity. Crucially, both OVs and Au nanoparticles work as “electron traps” to capture photogenerated electrons, thereby accelerating charge transfer. Based on the advantage of OVs and Au nanoparticles, ABMOH displays excellent MOA efficiency, and the degradation rate constant of ciprofloxacin (CIPF) by ABMOH-4 is 3.62-fold higher than BMO. Free radical trapping experiment and electron spin resonance suggest that singlet oxygen (1O2) can be selectively formed in the ABMOH system for CIPF degradation, and superoxide radical (•O2–) conversion and energy transfer are two pathways for 1O2 formation. This investigation serves as a beacon for the strategic design of high-performance and stable photocatalysts for MOA activation, paving the way for advancements in environmental remediation.