Hydroxyl Oxygen Research Articles

Synthesis, structural, DFT, antibacterial, antifungal, anti-inflammatory, and molecular docking analysis of new VO(II), Fe(III), Mn(II), Zn(II), and Ag(I) complexes based on 4-((2-hydroxy-1-naphthyl)azo) benzenesulfonamide

In this work, we synthesized and studied novel VO(II), Mn(II), Fe(III), Zn(II), and Ag(I) − 4-((2-hydroxy-1-naphthyl)azo) benzenesulfonamide complexes. Characterization techniques such as thermogravimetry (T.G.A), magnetic susceptibility testing, electrical conductivity studies, infrared spectroscopy, and mass spectroscopy all played crucial roles. Metal ions are coordinated by the azo Nitrogen (NN) and the hydroxyl Oxygen (–OH), as seen by the infrared spectra (IR). Our investigation of water's distribution and thermal behavior, in addition to its overall number, was made possible by techniques from thermogravimetry (T.G.A). The theoretical optimization of ligand (HL) and its metal complexes’ molecular structures was accomplished by the use of density functional theory (DFT). Other quantum chemical properties might potentially be derived by using the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels. In vitro testing was performed on both the ligand and its complexes to see whether or not they were capable of inhibiting the growth of harmful bacteria and fungi. The metal complexes have enhanced biological activity against the target microorganisms compared to the unbound ligand. In vitro research was also conducted on the anti-inflammatory effects of the aforementioned substances. Surprisingly, the AgL complex was the least active of the compounds tested, while the FeL complex was the most active. Based on molecular docking studies, we hypothesized that the synthesized compounds would bind to the cyclooxygenase-2 (COX-2) enzyme (Protein Data Base (PDB) ID: 5IKT) and the E. coli DNA gyrase B receptor (PDB ID: 1KNZ). Binding energies were calculated after studying protein-substrate interactions in depth. The molecular docking indications are that these compounds have physiological effects and might have broad use in the pharmaceutical industry.

Construction nanoenzymes with elaborately regulated multi-enzymatic activities for photothermal-enhanced catalytic therapy of tumor

In order to solve the limitation of tumor microenvironment on the anticancer effect of nanozymes, a multifunctional nanoenzyme Co/La-PB@MOF-199/GOx was designed in this work. By doping Co2+ and La3+ in different proportions, Co/La-PB with the optimal photothermal-enhanced catalytic performance was screened, which can catalyze H2O2 to generate more hydroxyl radicals (•OH) and oxygen, showing peroxidase (POD)-like and catalase(CAT)-like property. Through MOF-199 coating and loading glucose oxidase (GOx), a multifunctional nanoenzyme Co/La-PB@MOF-199/GOx was achieved. Due to the pH response of MOF-199, GOx can be accurately released into tumors to catalyze the reaction of glucose and oxygen to produce H2O2. In this process, the oxygen consumption can be compensated by the CAT-like property to realize continuous consumption of glucose and self-supply of H2O2 to continuously produce •OH. In the presence of high oxidation state metal ions (Co3+ and Fe3+), GSH consumption is accelerated to avoid weakening of •OH, showing the glutathione oxidase (GPx-like) activity. Besides, magnetic resonance imaging (MRI) experiments showed the potential application in imaging guided therapy. In vivo anti-tumor experiments showed a satisfactory anti-cancer effect through multi-enzymatic activities.

Luminescence, Paramagnetic, and Electrochemical Properties of Copper Oxides-Decorated TiO2/Graphene Oxide Nanocomposites

The properties of newly synthesized Cu2O/CuO-decorated TiO2/graphene oxide (GO) nanocomposites (NC) were analyzed aiming to obtain insight into their photocatalytic behavior and their various applications, including water remediation, self-cleaning surfaces, antibacterial materials, and electrochemical sensors. The physico-chemical methods of research were photoluminescence (PL), electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The solid samples evidenced an EPR signal that can be attributed to the oxygen-vacancy defects and copper ions in correlation with PL results. Free radicals generated before and after UV-Vis irradiation of powders and aqueous dispersions of Cu2O/CuO-decorated TiO2/GO nanocomposites were studied by EPR spectroscopy using two spin traps, DMPO (5,5-dimethyl-1-pyrroline-N-oxide) and CPH (1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine), to highlight the formation of hydroxyl and superoxide reactive oxygen species, respectively. The electrochemical characterization of the NC modified carbon-paste electrodes (CPE) was carried out by CV and DPV. As such, modified carbon-paste electrodes were prepared by mixing carbon paste with copper oxides-decorated TiO2/GO nanocomposites. We have shown that GO reduces the recombination process in TiO2 by immediate electron transfer from excited TiO2 to GO sheets. The results suggest that differences in the PL, respectively, EPR data and electrochemical behavior, are due to the different copper oxides and GO content, presenting new perspectives of materials functionalization.

A comparative study of Mannosylerythritol lipids (MELs) surfactant adsorption upon the Al12N12 and B12N12 nano-cages as potential candidates for detecting MELs

Aluminum nitride and boron nitride nanocages have recently been discovered. The properties of these compounds vary according to their size. In this paper, we study the adsorption of MELs on aluminum nitride and boron nitride nanocages in the solution phase using density functional theory. The results of adsorption energies indicate that during the adsorption on aluminum nanocages, ether oxygen atoms show stronger adsorption, while adsorption is stronger on boron nitride nanocage from the hydroxyl group oxygen. The results of thermodynamic calculations indicate that all adsorption positions of aluminum nitride are thermodynamically favorable. However, in the case of boron nitride, some positions are thermodynamically unfavorable. In terms of recovery time, borne nitride is not a good adsorbent because of very small recovery time. The aluminum nitride may be able to behave as a suitable sensor for the MELs in the solution phase. Nevertheless, boron nitride does not have this capability, since it does not significantly change the number of conducting electrons.

Birnessite MnO2 supported on CNTs in-situ for low-temperature oxidation of ethyl acetate

The removal of ethyl acetate has received much attention because excessive emissions of ethyl acetate are harmful to the environment and human health. Efficiently removing ethyl acetate under high space velocity requires low-cost catalysts operating at low temperatures. Herein, carbon nanotubes (CNTs) supported birnessite MnO2 catalysts were in-situ prepared by the redox reaction between KMnO4 and CNTs to maximize the interaction between MnO2 and support. The good thermal stability derived from the intact CNTs structure was important for the interaction between MnO2 and CNTs, contributing to the enhanced catalytic activity for ethyl acetate oxidation. 4MnO2-CNTs showed outstanding performance for the catalytic oxidation of ethyl acetate (100 ppm), achieving 100% removal efficiency and 99% CO2 selectivity at 160 °C under 100,000 mL·g−1·h−1 space velocity. In addition, 4MnO2-CNTs exhibited an excellent catalytic stability during the 50 h test period. Based on the comprehensive characterization study, we revealed that the activity of 4MnO2-CNTs could be effectively enhanced by the higher amount of active sites (Mn3+ and surface active adsorbed hydroxyl oxygen), as well as the strong interaction between MnO2 and support and the good thermal stability derived from the introduction of the intact CNTs structure.

Evaluation of anticancer activities, apoptosis, molecular docking, and antioxidant studies of new Ni(II), VO(IV), Cu(II) and Co(III) Schiff base complexes

New Schiff base complexes have been synthesized via appropriate conventional methods using 2-ethoxy-6-(E)-[(prop-2-em-1-yl)imino]methylphenol (HL) as a Schiff base ligand. The compounds obtained were characterized by spectral analysis and X-ray diffraction. Recrystallization from methanol provided single crystals with rod-shaped (1) and rhombus-shaped (2) shapes. The complexes were found to be composed of NiL2 and (VO)L2, with the anionic ligand L- acting as a bidentate ligand, coordinating to metal centers via imino N and hydroxyl oxygen atoms in all cases. Compound (1) crystallizes in the orthorhombic system with the Pccn space group, while compound (2) crystallizes in the monoclinic system with the P21/n space group. Cyclic voltammetry experiments in DMF show a metal-centered reduction peak at (−1.23), (−1.32), (−0.82, 1.36), and (−0.61, −1.55) V, corresponding to the Ni II/NiI, VO2+/VO+, CuII/CuI, and CoIII/II-CoII/I, respectively. The complexes were evaluated for anticancer activity in a human tumor cell line (HT-29). 5-fluorouracil was used as a standard drug. All tested compounds of Schiff base ligand and complexes (1–4) showed anticancer activity with inhibitory concentration (IC50) values of 85.28(HL), 15.13(1), 10.83(2), 28.53(3) and 30.21(4) (μM), respectively. The in vitro cytotoxicity screening results revealed that all compounds showed promising activity against colorectal cancer. In particular, compounds (1) and (2) showed excellent activity against tumor cell lines. The antioxidant activity of the synthesized Schiff base was determined using the DPPH method (1, 1-diphenyl-2- picryl hydrazyl). The effective concentration (EC50) indicates that all compounds have good antioxidant activity (EC50 = 143.02(HL), 168.03(1), 27.31(2), 160.3(3) and 173.41(4). The biological activity spectra of synthesized compounds are predicted by the Pass Online Web Resource. In addition to the PASS program's prediction, molecular docking studies were also performed to find bind affinity to protein cyclooxygenase inhibitor (the structure PDB code 1CX2).

MgO/Co3O4 composite activated peroxymonosulfate for levofloxacin degradation: Role of surface hydroxyl and oxygen vacancies

Heterogeneous activation of peroxymonosulfate (PMS) by transition metal oxides has drawn more and more attention in the past decades, while the loss of M−OH on the catalyst surface has been a primary rate-limiting factor for PMS activation. Here, the MgO/Co3O4 composite with hydroxyl groups and oxygen vacancies (Ov) were obtained by modifying Co3O4 with alkaline earth metal oxide MgO, and used for activating PMS to remove levofloxacin (LEV). LEV removal rate constant (kapp) in the MgO/Co3O4-PMS system was 0.9077 min−1. It is above 124 and 101 times that of the (MgO + Co3O4)-PMS mixed mechanically system (0.0073 min−1) and the sum of MgO-PMS (0.0025 min−1) and Co3O4-PMS (0.0064 min−1) systems. The MgO/Co3O4-PMSsystem achieved effective LEV removal in a wide range of pH from 3.00 to 10.00, as well as excellent reusability and universality. Effects of various factors, such as reaction temperature, anions, and organic matter on the removal of LEV were explored. The activation energy of MgO/Co3O4 for LEV degradation was 27.50 kJ mol−1. X-ray photoelectron spectroscopy and electrochemical characterization revealed that MgO incorporation enhanced surface hydroxyl level and electronic transfer ability of Co3O4. The existence of Ov was confirmed by electron paramagnetic resonance characterization. Ov can accelerate the Co2+/Co3+ cycle to enhance PMS activation. Radical quenching tests and EPR trials proved the combined action of radicals (•OH, SO4•–) and non-radical (1O2) pathways for the efficient oxidative decomposition of LEV. The likely mechanism of PMS activation by the MgO/Co3O4 and LEV degradation pathways were discussed.

A comparative study of TiO2 preparation method on their photocatalytic activity for CO2 reduction

In this work, we aimed to correlate the structural properties of different TiO2 with their photocatalytic performance and selectivity during CO2 photocatalytic reduction at different pH. We prepared two types of TiO2 photocatalysts and characterized them in detail using X-ray powder diffraction, field emission scanning electron microscope, nitrogen adsorption, UV-Vis spectroscopy, photoelectrochemical measurements and X-ray photoelectron spectroscopy techniques. The prepared photocatalysts demonstrated significantly higher selectivity to CO2 reduction (CH4 and CO yields), than a commercial P25. Among them, the photocatalysts TiSG, which had the lowest portion of hydroxyl oxygen species, had the highest photoreduction efficiency. Therefore, the key factors in photocatalytic CO2 reduction with TiO2 are not only the phase composition but also the portion of different types of surface oxygen species, which strongly affects their efficiency and selectivity. Another objective was to investigate the effect of pH on the efficiency and especially the selectivity of photocatalytic CO2 reduction. While methane is mainly formed in basic environments, carbon monoxide is formed in more acidic environments. Also, hydrogen production is twice as high in more acidic environment compared to the basic environment.

Oxygen vacancies induced ferromagnetism in RF-sputtered and hydrothermally annealed zinc ferrite (ZnFe2O4) thin films

We report the inception of substantial magnetization of 4107 G in rf-sputtered and annealed hydrothermally at 180 °C zinc ferrite (ZFO) thin films. The value of electron-phonon coupling strength (λ) calculated using Raman A1g and F32g modes contended the shift of inverse spinel structure of the as-prepared thin films to the normal spinel structure with the enhancement in annealing duration. The shift in spinel structure was further affirmed by X-ray photoelectron spectroscopy (XPS) where inversion parameter, i.e., a fraction of the Zn2+ ions occupied by octahedral sites reduced from 0.18 of as-deposited film to 0.13 of air annealed and 0.14 for hydrothermally annealed films. Additionally, the ZFO thin film annealed hydrothermally for 4 h showed lower value of λ of 0.11 for A1g Raman mode and a high value of the ratio of surface hydroxyl (OH− groups) oxygen ions (Oii) to the lattice oxide (Fe/Zn–O) oxygen ions (Oi) in XPS spectra confirmed the presence of enormous oxygen vacancies. The magnetization analysis suggested that the presence of high oxygen vacancies in 4 h of hydrothermally annealed sample promotes the direct ferromagnetic interaction in Fe3+ ions in octahedral sites leading to a high value of saturation magnetization unlike the air annealed samples.

Coordination configurations of cupric tartrate in electronic industry wastewater

The coordination structure of cupric tartrate (Cu—TA) complex was investigated by ultraviolet—visible (UV–Vis) and liquid chromatography/mass spectrometer (LC–MS) firstly; furthermore, effective coordination configurations and electronic properties of Cu—TA in aqueous solution were systematically revealed by density functional theory (DFT) calculations. Consistently, Job plots show the possible existence of [Cu(TA)] and [Cu(TA)2]2– at 230 and 255 nm based on UV–Vis results. LC–MS results confirm the existence of the single and high coordination complexes [Cu2(TA)2]+, [Cu(TA)2]+ and [Cu2(TA)3(H2O)2(OH)2]2+. DFT calculation results show that carboxylic oxygen and hydroxyl oxygen of tartaric acid (TA) are preferred sites for Cu(II) coordination. [Cu(TA)] (1H, 3H sites O of TA coordinated with Cu(II)), [Cu(TA)2]2– (two 1C, 2H sites O of TA coordinated with Cu(II)), and [Cu(TA)3]4– (three 2H, 3H sites O of TA coordinated with Cu(II)) should be dominant coordination configurations of Cu—TA. The corresponding Gibbs reaction energies are –170.1, –136.2, and –90.2 kJ/mol, respectively.

Synthesis of Bimetallic FeCu-MOF and Its Performance as Catalyst of Peroxymonosulfate for Degradation of Methylene Blue.

Bimetallic MOFs have recently emerged as promising materials for wastewater treatment based on advanced oxidation processes. Herein, a new bimetallic MOF (FeCu-MOF) was fabricated by hydrothermal process. The structural, morphological, compositional and physicochemical properties of the as-synthesized bimetallic FeCu-MOF were characterized by XRD, FT-IR, SEM, TEM, BET, and XPS. TEM and XPS confirmed the homogeneous distribution of CuO2 nanoparticles in the as-synthesized materials. The result of wastewater treatment indicated that 100% of MB was removed by 6.0 mM PMS activated with 0.6 g/L of FeCu-MOF in 30 min. The high catalytic performance of FeCu-MOF was probably due to the accelerated electron and mass transfer resulting from the existence of a homogeneous distribution of unsaturated metal sites and an abundant mesoporous structure. The obtained results from the competitive quenching tests demonstrated that sulfate radicals (SO4•−) were the major species responsible for MB oxidation. In addition, hydroxyl (·OH) and singlet oxygen (1O2) also had a nonnegligible role in the MB removal. Interestingly, the addition of acetate ion (CHCOO−) promoted the removal of MB while other anions (including NO2−, H2PO4−, SO42−, HPO42−, and HCO3−) inhibited the MB removal. Furthermore, a possible mechanism based on both heterogeneous and homogeneous activation of PMS was proposed, along with the MB degradation mechanism.

Hydroxylation and water-surface interaction for S-glass and silica glass using ReaxFF based molecular dynamics simulations

Hydrolysis at the water-glass interface significantly influences glass surface reactivity and adhesion characteristics. In glass fiber reinforced epoxy composite interphases, hydroxyls on the glass fiber surface reacts with silane coupling agents to form covalent bonds between the fiber and polymer matrix. In this study, the surface reactivity and hydrolysis reaction of silica glass and S-glass (Mg aluminosilicate glass with 65 % SiO2, 25 % Al2O3, and 10 % MgO in weight ratio) are simulated using ReaxFF molecular dynamics (MD) to investigate the formation of surface defects (i.e., under-coordinated atoms) and hydroxyls (number density, types and spatial distribution) at four surface annealing temperature conditions (300 K, 700 K, 1000 K and 1300 K). Our study showed that a higher areal number density of surface defects and hydroxyls formation occur at lower surface annealing temperature conditions. S-glass was predicted to have a lower number density of hydroxyls compared to pure silica glass. In addition, analysis on hydroxyl oxygen revealed the defects and oxide bond connected to Mg are responsible for hydrolysis in S-glass. RDF and hydroxyl categorization analysis revealed the S-glass could have closer proximity among hydroxyls despite the lower hydroxyl areal number density than silica glass. Lastly, silica glass showed more physisorbed water and surface energy, which agrees with previous studies. This surface hydrolysis and reactivity analysis study will guide the experiments to control the fiber coating process to tailor interphase in glass fiber-epoxy composites.

The role of the spatial arrangement of single rhodium sites on ZSM-5 in the oxidative methane carbonylation to acetic acid

Single atom rhodium catalysts based on microporous ZSM-5 zeolite (SiO2/Al2O3 = 30) were studied in the reaction of oxidative methane carbonylation to acetic acid. For highly dispersed rhodium distribution on the zeolite surface, nitrogen-containing polymers, namely chitosan hydrochloride, polyethyleneimine, and polyvinylpyrrolidone, were used. Using XAS spectroscopy, all rhodium was found to be as single atom metal sites in the zeolite structure, which contributes to the acetic acid formation. The catalytic properties of rhodium zeolite catalysts in the oxidative methane carbonylation to acetic acid were revealed to depend not only on the single atom rhodium distribution and the catalyst acidity, but also on the spatial rhodium atom arrangement in the zeolite, which was established by the XPS. According to DFT calculations in combination with EXAFS modeling, rhodium anchored at the zeolite channel intersections was shown to be coordinated with four zeolite oxygen atoms and one hydroxyl group oxygen atom and be the dominant catalytic species in the acetic acid formation.

Oral Nanomotor-Enabled Mucus Traverse and Tumor Penetration for Targeted Chemo-Sono-Immunotherapy against Colon Cancer.

The therapeutic outcomes of oral nanomedicines against colon cancer are heavily compromised by their lack of specific penetration into the internal tumor, favorable anti-tumor activity, and activation of anti-tumor immunity. Herein, hydrogen peroxide (H2 O2 )/ultrasound (US)-driven mesoporous manganese oxide (MnOx )-based nanomotors are constructed by loading mitochondrial sonosensitizers into their mesoporous channels and orderly dual-functionalizing their surface with silk fibroin and chondroitin sulfate. The locomotory activities and tumor-targeting capacities of the resultant nanomotors (CS-ID@NMs) are greatly improved in the presence of H2 O2 and US irradiation, inducing efficient mucus-traversing and deep tumor penetration. The excess H2 O2 in the tumor microenvironment (TME) is decomposed into hydroxyl radicals and oxygen by an Mn2+ -mediated Fenton-like reaction, and the produced oxygen participates in sonodynamic therapy (SDT), yielding abundant singlet oxygen. The combined Mn2+ -mediated chemodynamic therapy and SDT cause effective ferropotosis of tumor cells and accelerate the release of tumor antigens. Importantly, animal experiments reveal that the treatment of combining oral hydrogel (chitosan/alginate)-embedding CS-ID@NMs and immune checkpoint inhibitors can simultaneously suppress the growth of primary and distal tumors through direct killing, reversion of immunosuppressive TME, and potentiation of systemic anti-tumor immunity, demonstrating that the CS-ID@NM-based platform is a robust oral system for synergistic treatment of colon cancer.

Adsorption behavior and mechanism for Pb(II) and Cd(II) by silica anchored salicylaldehyde modified polyamidoamine dendrimers

BackgroundWater pollution caused by Pb(II) and Cd(II) poses severe threat to human beings. Construction of adsorbent for efficient adsorption of these ions is of vital importance. Polyamidoamine (PAMAM) dendrimers based adsorbents displayed excellent binding ability for metal ion. MethodsSilica anchored salicylaldehyde modified polyamidoamine dendrimer (G0-S, G1-S, and G2-S) have been prepared for removing these ions. The adsorption behavior and mechanism was systematically reveled via batch experiments and theoretical calculation. Significant findingsG1-S is the most efficient adsorbent that exhibits highest adsorption at pH 6.0 for these ions. Kinetic adsorption is dominated by film diffusion and fitted by pseudo-second-order model. The adsorption of these ions can be enhanced by elevating temperature and concentration. Adsorption isotherm process fits Langmuir model and is spontaneous, endothermic and randomness increased in nature. Adsorption mechanism indicates imino and tertiary amine nitrogen, hydroxyl and carbonyl oxygen participate in the adsorption, and imino nitrogen atoms dominate the coordination.

Corrosion inhibition mechanism of Xanthium sibiricum inhibitor and its comprehensive effect on concrete performance: Experimental analysis and theoretical calculation

• Xanthium coriander corrosion inhibitor can effectively reduce the corrosion current and increase the corrosion potential. Its adsorption behavior conforms to the Frumkin adsorption theory. • The corrosion inhibition mechanism is as follows: the adsorption active site of 1,5-dicaffeoylquinic acid is phenolic hydroxyl oxygen, and the phenolic hydroxyl oxygen on the surface of Fe (1 1 0) hybridizes with the 3d empty orbital of Fe to form a covalent bond. • Carboxylic acid group of 1,5-dicaffeoylquinic acid is ionized, and there is a tight bond between the oxygen atom in the –COOå − group and the calcium ion to form a coordination complex. • Xanthium cocklebur corrosion inhibitor has the functions of retarding, strengthening and rusting, and the optimal concentration is 2 g/L. • Under the optimal concentration, the proportion of residual strength of steel fiber reinforced concrete is about 10% higher than that of steel fiber reinforced concrete without corrosion inhibitor. Aiming at the corrosion inhibition mechanism of Xanthium japonica corrosion inhibitor and its comprehensive influence on concrete performance, this paper carried out in-depth exploration through potentiodynamic polarization curve method, XPS and SEM and other detection methods, combined with quantum chemical calculation and molecular dynamics simulation. The study found that the Xanthium cocklebur corrosion inhibitor can effectively reduce the corrosion current and increase the corrosion potential. It is a composite corrosion inhibitor. Its adsorption behavior conforms to the Frumkin adsorption theory, and can form a relatively stable adsorption film on the surface of carbon steel, with global adsorption characteristics. The corrosion inhibition mechanism is as follows: the phenolic hydroxyl oxygen of 1,5-dicaffeoylquinic acid hybridizes with the 3d empty orbital of Fe to form a covalent bond; the hydroxyl hydrogen and the hydroxyl oxygen on the surface of γ-FeOOH (0 1 0) are connected by hydrogen bond. Xanthium cocklebur has the functions of retardation, enhancement and rust inhibition, and the optimal concentration is 2 g/L. The mechanism of retardation is that phenolic acid molecules contain complex forming groups, which can form coordination complexes with calcium ions in an alkaline environment, and control the concentration of calcium ions in the pore liquid of steel fiber reinforced concrete in the early stage of hydration.

Syntheses, crystal structures and fluorescent properties of imidazole based mixed-ligand nickle and cadmium complexes

Four novel mixed-ligand nickle and cadmium complexes [Cd(tolu)2(imi)3] (1) [CdCl2(imi)2]n (2), [Ni(imi)6](tolu)2 (3) and [Ni(mand)2(imi)2]·H2O (4) (imi = imidazole, Htolu = o-toluic acid, Hmand = mandelic acid) were synthesized and isolated in solid state based on nickle and cadmium salts, imidazole and different carboxylic acids. These complexes were characterized by FT-IR, elemental analyses, thermogravimetric (TG) analyses, UV–vis, X-ray structural analyses and fluorescence spectra. Complexes 1 and 4 are neutral mixed-ligand molecules. Complex 2 exhibits a 2D chain constructed by [CdCl2(imi)2] units. Complex 3 possesses [Ni(imi)6]2- anions with uncoordinated tolulate anions. In complexes 1–4, each imidazole ligand provides one nitrogen atom for coordination. Tolulate and mandelate ligands coordinate to the metal through carboxyl oxygen or hydroxyl oxygen atoms. Plenty of intramolecular hydrogen bonds as N–H⋯O and O–H⋯O interactions are observed in these complexes. Fluorescence properties of the complexes have been deeply investigated and the result reveals that Fe3+ ion has the greatest effect on fluorescence intensity of complex 3. The fluorescence intensity decreases with the increase of iron concentration.

Enhanced the synergistic degradation effect between active hydroxyl and reactive oxygen species for indoor formaldehyde based on platinum atoms modified MnOOH/MnO2 catalyst

Maintaining high activity during prolonged catalysis is always the pursuit in catalytic degradation of organic pollutants. For indoor formaldehyde (HCHO) degradation, the accumulation of intermediates is the major factor limiting the conversion of HCHO to final product CO2 (HCHO-to-CO2 conversion) and long-lasting catalysis. Herein, a three-dimensional radialized nanostructure catalyst self-assembled by MnOOH/MnO2 nanosheets anchored with Pt single atoms (PtSA-MnOOH/MnO2 with a trace platinum loading amount of 0.09%) is developed by thermally assisted two-step electrochemical method, which achieves enhanced CO2 production in catalytic HCHO degradation at the room temperature by the collaborative action of active hydroxyl (OH*) and active oxygen species (O2*). By boosting intermediates’ decomposing, the catalyst implements real-time HCHO-to-CO2 conversion (∼85.7%) and long-term continuous HCHO removal (∼98%) during 100 h in a 15 ppm HCHO atmosphere at 25 °C under a weight hourly space velocity of 30000 mL/gcat∙h. Density functional theory calculation shows that the formation energy of O2* from O2 over PtSA-MnOOH/MnO2 is nearly half lower than that over Pt-MnO2 catalyst. And decomposing accumulated intermediates gives the credit to OH* species sustainably generated by the combined action of MnOOH and O2*. The synergistic action between PtSA and MnOOH contributes to the continuous production of O2* and OH* for enhancing CO2 production in indoor catalytic formaldehyde degradation.

Ceria-promoted heterogeneous Fenton-like oxidation of polyvinyl alcohol, Rhodamine-B, and Reactive Red X-3B over Fe/Cu@γ-Al2O3 microspheres under neutral conditions

To improve the catalytic activity and stability of a copper-iron-based Fenton-like system, the element cerium was added to the Cu-Fe-based catalyst via spray drying-calcination method. Polyvinyl alcohol (PVA) was chosen as the target pollutant to evaluate the properties of the ceria-promoted Fe/Cu@γ-Al2O3 (Ce-Fe/Cu@γ-Al2O3) microspheres. The experimental results showed that the PVA removal rate reached 99.74% in the Ce-Fe/Cu@γ-Al2O3/H2O2 system. After 10 consecutive catalytic reactions, the PVA removal rate was still maintained above 96%. Comparative experimental results showed that the addition of Ce significantly improved the catalytic activity and stability of the Cu-Fe-based catalyst. In addition, this catalytic system also showed good degradation efficiency for Rhodamine-B and Reactive Red X-3B dyes, with removal rates reaching 99.97% and 99.94%, respectively. The mechanism of the synergistic effect of Cu, Fe, and Ce was established, and electron paramagnetic resonance (EPR) experiments revealed that hydroxyl (·OH), superoxide (O2·-), and singlet oxygen (1O2) radicals were involved in the catalytic degradation of PVA. This study demonstrates a novel spray drying-calcination method for the preparation of Ce-Fe/Cu@γ-Al2O3 microspheres with outstanding catalytic activity and stability in Fenton-like systems. The Ce-Fe/Cu@γ-Al2O3 catalyst prepared in this research provides a potential alternative for the efficient removal of organic pollutants in wastewater.

Electrochemical oxidation of lamivudine using graphene oxide and Yb co-modified PbO2 electrodes: characterization, influencing factors and degradation mechanisms

In this work, a new type of graphene oxide and Yb co-modified PbO2 electrode (Yb-GO-PbO2) was prepared by the electrodeposition method. Lamivudine was selected as the model contaminant to evaluate the electrochemical performance of the Yb-GO-PbO2 electrode, and it was found that the Yb-GO-PbO2 electrode could obviously enhance the degradation of lamivudine compared with the PbO2 electrode. Meanwhile, the Yb-GO-PbO2 electrode was systematically characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), which showed that the Yb-GO-PbO2 electrode processed a denser surface, smaller crystal size, and a greater proportion of hydroxyl oxygen species. Electrochemical measurements demonstrate that the Yb-GO-PbO2 electrode processes many prominent features compared to the PbO2 electrode, such as larger electrochemically active surface area, smaller charge transfer resistance, and higher oxygen evolution potential. The effects of lamivudine initial concentration, current density, electrolyte concentration, and initial pH on the degradation of lamivudine were studied and analyzed. The removal rates of lamivudine and COD reached 99.6% and 65.1%, respectively, when treated for 120 min under optimal process conditions. The electrochemical degradation of lamivudine fitted pseudo-first-order reaction kinetics. The intermediates of lamivudine degradation were determined using UPLC-MS, and possible degradation pathways of lamivudine were proposed. This paper provides a promising approach for enhancing the electrochemical oxidation performance of PbO2 electrodes by introducing GO and Yb.