Resonance Characterization Research Articles

Characterization of a Dual Nonlinear Helmholtz Resonator.

Resonant elements can generate small amounts of energy that make them pertinent for feeding miniaturized accelerometers with the energy needed. Suitable oscillator candidates are Helmholtz resonators, which have been, for a long time, analyzed and designed within the context of linear vibration. This study focuses on extracting nonlinear characteristics of a dual Helmholtz resonator (HR), with a neck-cavity-neck-cavity configuration, mounted on an acoustic waveguide with harmonically oscillating pressure. The mathematical model used for describing the resonator embraces inherent nonlinear air stiffness and the damping nonlinearity of hydrodynamic origin. Numerical solutions for the resonator's nonlinear oscillations are obtained. Bifurcation diagrams are produced, indicating that the dual HR behaves in a deterministic fashion within the engineering practical limits. Phase portraits are drawn for the system, showing a quasi-periodic motion. Frequency response curves (FRC) are found to shift to the left at the lower resonant frequency indicating a softening behavior. FRC keep generally symmetric curves at the higher resonant frequency indicating a mostly linear behavior.

A dual-MOFs (Fe and Co)/g-C3N4 heterostructure composite for high-efficiently activating peroxymonosulfate in degradation of sertraline in water

A dual-MOFs (Fe and Co)/g-C3N4 heterojunction composite was successful constructed and used to activate peroxymonosulfate (PMS) for degrading sertraline (SER). The composite showed outstanding catalytic activity with 100% of SER removal efficiency in 60 min and the degradation rate 0.057 min−1. At the same time, the amount of catalyst, concentration of PMS and environmental pH on the degradation for SER were investigated in detail. The main degradation products and pathways of SER were analyzed by Gaussian theory calculation and high-performance liquid chromatography-mass spectrometry (HPLC-MS). Based on the free radical quenching experiments and electron paramagnetic resonance (EPR) characterization analysis, it was confirmed that •OH and SO4•- were produced in the catalytic reaction process, and explained catalytic mechanism elaborately. This work demonstrates the connection of MOF-Fe nanoparticles, micropores and heterojunction with the catalytic activity, providing an efficient catalytic system that can promote electron transfer and circulation of high activity center.

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.

One-Step Regio- and Stereoselective Electrochemical Synthesis of Orexin Receptor Antagonist Oxidative Metabolites.

Synthesis of drug metabolites, which often have complex structures, is an integral step in the evaluation of drug candidate metabolism, pharmacokinetic (PK) properties, and safety profiles. Frequently, such synthetic endeavors entail arduous, multiple-step de novo synthetic routes. Herein, we present the one-step Shono-type electrochemical synthesis of milligrams of chiral α-hydroxyl amide metabolites of two orexin receptor antagonists, MK-8133 and MK-6096, as revealed by a small-scale (pico- to nano-mole level) reaction screening using a lab-built online electrochemistry (EC)/mass spectrometry (MS) (EC/MS) platform. The electrochemical oxidation of MK-8133 and MK-6096 was conducted in aqueous media and found to produce the corresponding α-piperidinols with exclusive regio- and stereoselectivity, as confirmed by high-resolution nuclear magnetic resonance (NMR) characterization of products. Based on density functional theory (DFT) calculations, the exceptional regio- and stereoselectivity for this electrochemical oxidation are governed by more favorable energetics of the transition state, leading to the preferred secondary carbon radical α to the amide group and subsequent steric hindrance associated with the U-shaped conformation of the cation derived from the secondary α-carbon radical, respectively.

Efficient activation of peroxydisulfate by FeNC for chloramphenicol degradation: Performance and mechanisms

In this study, a green Fe and FeN co-doped carbon nanocomposite catalyst (FeNC) was synthesized by a simple and economical method and applied to activate peroxodisulfate (PDS) for the efficient oxidation of chloramphenicol (CAP). Characterization analysis found that the surface of Fe and FeN nanoparticles supported on nitrogen-doped carbon was wrapped by nitrogen-doped carbon nanosheets, forming a "core-shell" structure. The FeNC@PDS system has good catalytic activity, and the CAP degradation efficiency reaches 91.2% within 60 min. FeNC@PDS system exhibits excellent catalytic degradation performance under a wide pH range (2.4–8.3) and shows good reusability. The calculated % reaction stoichiometric efficiency (RSE) reached values up to 18.86%, which exceeds than those of various reported heterogeneous Fenton-like systems. Quenching experiments and electron paramagnetic resonance characterization confirmed that both free-radicals and non-radicals were involved in the activation of PDS by FeNC. In addition, the possible mechanism of the PDS activation by FeNC was proposed. Finally, the degradation pathway of CAP was determined based on the intermediates. This work provided a novel reference for the design of efficient heterogeneous catalysts to remove organic pollutants efficiently.

Coupling a titanium dioxide based heterostructure photoanode with electroless-deposited nickel-phosphorus alloy coating on magnesium alloy for enhanced corrosion protection

• Covalent organic framework (COF) modified TiO 2 nanoarray composite was prepared. • Composite shows superior photoelectrochemical conversion and cathodic protection. • Achieved 0.42 mA cm −2 photocurrent density and 0.66 V open circuit potential drop. • Formation of a direct Z-scheme heterojunction between COF and TiO 2 is verified. • Synergistic corrosion protection of ni interlayer and composite is discussed. The utilization of photoelectrochemical cathodic protection (PECCP) enables an indirect corrosion protection of metals with low self-corrosion potential by introducing a metallic nickel interlayer. However, the ability to enhance the PECCP efficiency remains challenging because of the inherent property of the semiconductor. Herein, this ability is demonstrated by coupling a covalent organic framework (TpBD) decorated TiO 2 photoanode (TiO 2 /TpBD) with nickel coating on magnesium alloy for an effective corrosion protection. The composite photoanode showed direct PECCP for the nickel interlayer and indirect corrosion protection of the magnesium alloy. The composite structure of the nanotube array and the covalent organic framework for the photoanode were confirmed by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The enhanced photoelectrochemical conversion capability and PECCP performance of the nickel-coated Mg alloy were evidenced by the results from electrochemical and photoelectrochemical measurements including Mott-Schottky curves, photoinduced potential variations, and electrochemical impedance spectroscopy (EIS). Lastly, a corrosion protection mechanism is proposed, where the enhanced PECCP efficiency is attributed to the formation of a direct Z-scheme heterojunction, which is substantiated by the results from valence band (VB) XPS and electron spin resonance characterizations.

Mechanical Properties of High Temperature Vulcanized Silicone Rubber Aged in the Natural Environment.

Composite insulators operate in harsh field environments all year round. Their various properties and states of aging require attention. It is important to study the performance changes of composite insulator sheds after aging to evaluate the life of insulators operating on grids. For this reason, 22 composite insulator sheds from different factories, with different voltage levels and different ages years were selected to conduct mechanical properties testing. The mechanical properties include hardness, tensile strength, and elongation at break, and were investigated by thermogravimetric (TGA) testing, surface morphology, and nuclear magnetic resonance (NMR) characterization. The changes in mechanical properties of high temperature vulcanization (HTV) composite insulator silicone rubber aged in the natural environment were analyzed, including the reasons for these changes. The results showed that the transverse relaxation time T2 of the sample was closely related to its aging state. The more serious the silicone rubber’s aging, the smaller was the T2. The state of the composite insulator can be evaluated by using T2 and aging years simultaneously. With the actual degree of aging in the silicone rubber intensified, its tensile strength and elongation at break generally showed a downward trend.

Insights into the liquid extraction mechanism of actual high-strength phenolic wastewater by hydrophobic deep eutectic solvents

Liquid-liquid extraction using recently developed hydrophobic deep eutectic solvents (HDESs) shows great potential for the removal of phenol from wastewater. But most of the research limited themselves by being focused on the wastewater with phenol concentration lower than 1000 mg·L−1 and most importantly, the extraction mechanism is still lacking in deep understanding. We pilot to remove phenol from actual industrial wastewater containing ultra-high-concentration phenol (∼54,000 mg·L−1) using HDESs, and also carried out a systematic investigation on their extraction mechanism. Eight HDESs composed of dl-menthol (hydrogen bond acceptor, HBA) and various fatty acids (hydrogen bond donor, HBD) were synthesized and the effects of various important conditions, such as HBA/HBD molar ratio, HDES/wastewater mass ratio, and initial concentration of phenol in wastewater, on their extraction efficiencies were evaluated. The experimental results showed that all the prepared HDESs possess excellent extraction capacity for phenol with the best one being obtained from dl-menthol/nonanoic acid (C9) based HDES (molar ratio 2:1) within 5 min at room temperature (97 %). Successive extraction was performed to minimize the amount of solvents used for economic consideration. Regeneration and reuse of HDESs after phenol extraction was achieved by activated carbon recovery. The extraction mechanism was investigated experimentally by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) characterization, together with the predicted activity coefficients of phenol in solvents by COSMO-RS model and experimentally determined distribution coefficient (D) between HDES and aqueous phase. The hydrogen bond formed between HDES and phenol during extraction was experimentally identified. Moreover, quantum computation by DFT method was applied to model the extraction process, and the extraction mechanism was investigated more in-depth by theoretical computation. The results of DFT calculation provided good agreement with the experimental data and a new six-membered ring-like structure formed during the extraction process between HDES and phenol molecule was suggested for the first time to the best of our knowledge. We hope this work will provide guidance on the study of liquid extraction process/mechanism using HDESs and promote their practical application in the future.

Cardiac magnetic resonance characterization and prediction of left ventricular thrombus after ST-segment elevation myocardial infarction

Abstract Background Left ventricular thrombus (LVTh) is an uncommon yet serious complication after ST-segment elevation myocardial infarction (STEMI). Late gadolinium enhancement (LGE) sequences in cardiac magnetic resonance (CMR) imaging allows for accurate detection of LVTh. However, the implications of CMR to predict and characterize LVTh occurrence is this population is unclear. Purpose We aim to characterize the incidence, outcomes, and predictors of LVTh after STEMI by CMR imaging. Methods Our registry comprised 455 patients admitted for a first reperfused STEMI in our university hospital. Baseline characteristics were recorded. All patients underwent early (1-week) and late (6-month) CMR. Left ventricular ejection fraction (LVEF, %), infarct size (% of left ventricular mass) and microvascular obstruction (MVO, number of segments) were measured. LGE sequences were used to analyze the presence of LVTh. Patients with LVTh at 6-month CMR underwent an additional CMR 1 year after admission. Univariate and multivariate comparisons were performed to study the ocurrence of LVTh in the first 6 months after STEMI. Results Mean age was 58.24±11.69 years, most patients were male (82.6%) and anterior infarction occurred in more than half of the cohort (52.7%). LVTh was detected in 36 (7.9%) patients in the first 6 months after STEMI. Anticoagulation was initiated in all cases. Of these, 27 patients had LVTh at early (1-week) CMR, but 9 had LVTh at late (6-month) CMR with no prior evidence of LVTh at early CMR. A total of 6 patients had persisting LVTh at 1-year CMR (37.5% of patients with 6-month LVTh). In multivariable analysis, anterior infarction (HR 6.6 [1.91–22.83], p<0.001) and 1-week CMR-LVEF (HR 0.97 [0.93–0.99], p=0.04) and MVO (HR 1.19 [1.02–1.39], p=0.03) independently predicted the occurrence of LVTh in the first 6 months after STEMI. We computed a risk score of LVTh assigning 1 point to each of these variables (anterior infarction, CMR-LVEF <50% and MVO >3.5 segments), which allowed us to stratify the risk of LVTh in the first 6 months after STEMI (0.6% if 0 points, 3.8% if 1 point, 14.4% if 2 points, and 31.2% if 3 points). Conclusions CMR imaging soon after STEMI can contribute relevant prognostic value regarding LVTh occurrence after the acute event. Patients with anterior infarction, LVEF <50% and MVO in >3.5 segments at early (1-week) CMR have the highest risk of LVTh in the first 6 months after STEMI. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Instituto de Salud Carlos III and “Fondos Europeos de Desarrollo Regional FEDER” and Conselleria de Educaciόn – Generalitat Valenciana.

Z-scheme heterojunction composed of Fe doped g-C3N4 and MoS2 for efficient ciprofloxacin removal in a photo-assisted peroxymonosulfate system

Herein, a series of Z-type heterojunctions FexCN@MoS2-Y were synthesized by a combination of calcination and hydrothermal methods for the removal of ciprofloxacin (CIP) by peroxymonosulfate (PMS) activation under visible light. It was optimized that Fe3CN@MoS2-4 exhibited excellent photocatalytic performance, with the degradation rate of CIP 84 % within 140 min. Besides, its rate constants were 23.74, 3.59, and 3.98 times higher than those of pure g-C3N4, Fe3CN, and MoS2, respectively. Furthermore, the Fe3CN@MoS2-4/PMS/vis system could efficiently degrade other antibiotics (enrofloxacin (ENRO), metronidazole (MNZ) and tetracycline (TC)). The quenching experiments and electron paramagnetic resonance (EPR) characterization showed that reactive substances such as 1O2, h+ and Ovs played a dominant role in this system. We deeply explore the possible mechanisms and CIP degradation pathways for the enhanced CIP degradation efficiency in the Fe3CN@MoS2-4/PMS/vis system. Among them, the exposed Mo (IV) and Fe (II) sites on the catalyst surface accelerated the electron transfer, while the S2- therein promoted the cycling between ions, thus increasing the reaction rate. Finally, Fe3CN@MoS2-4 maintained appreciable performance even after 5 cycles. This study may provide a new approach for the development of metal-doped g-C3N4-based complexes.

A 1D helical eco-friendly Mn(II) halide coordination polymer: Luminescent properties involving resonant energy transfer and magnetic characterization

In the present work, we discuss the synthesis of nontoxic Mn(II) halide coordination polymer and explore the potential light emission properties for solar-cell devises through experimental and computational studies. The crystal structure was unveiled through Single Crystal Diffraction, whereas physical properties were investigated by means of thermal, spectroscopic, magnetic, optical and photoluminescence measurements. The observed left-right handed helical structure is built up from an infinite 1-D chains of Mn(II) octahedra. The polymeric network is stabilized through inter-molecular hydrogen bonding interactions and π···π face-to-face interactions. Furthermore, ferro-antiferromagnetic ordering has been proven through magnetic measurements. A deep investigation of the photoluminescence study reveals the presence of a bright bluish light emission with corresponding CIE color coordinates of (0.27, 0.35), CCT value of 8092 K and a very high CRI value of 96. The origin of this intense light emission is mainly attributed to the occurrence of the resonant energy and charge transfer processes between Triazolate ligand and inorganic Mn–Cl sub-lattices. Such behavior leads to the conversion of Frenkel excitons localized within the organic part to Mott-Wannier excitons localized in inorganic clusters. Based on these results, we strongly believe that the elaborated material can be a promising candidate for eco-friendly electronic applications.

Efficient Charge Transfers in Highly Conductive Copper Selenide Quantum Dot-Confined Catalysts for Robust Oxygen Evolution Reaction.

Defective quantum dots (QDs) are the emerging materials for catalysis by virtue of their atomic-scale size, high monodispersity, and ultra-high specific surface area. However, the dispersed nature of QDs fundamentally prohibits the efficient charge transfer in various catalytic processes. Here, we report efficient and robust electrocatalytic oxygen evolution based on defective and highly conductive copper selenide (CuSe) QDs confined in an amorphous carbon matrix with good uniformity (average diameter 4.25 nm) and a high areal density (1.8 × 1012 cm-2). The CuSe QD-confined catalysts with abundant selenide vacancies were prepared by using a pulsed laser deposition system benefitted by high substrate temperature and ultrahigh vacuum growth conditions, as evidenced by electron paramagnetic resonance characterizations. An ultra-low charge transfer resistance (about 7 Ω) determined by electrochemical impedance spectroscopy measurement indicates the efficient charge transfer of CuSe quantum-confined catalysts, which is guaranteed by its high conductivity (with a low resistivity of 2.33 μΩ·m), as revealed by electrical transport measurements. Our work provides a universal design scheme of the dispersed QD-based composite catalysts and demonstrates the CuSe QD-confined catalysts as an efficient and robust electrocatalyst for oxygen evolution reaction.

2D time-domain nuclear magnetic resonance (2D TD-NMR) characterization of cell wall water of Fagus sylvatica and Pinus taeda L.

2D time-domain nuclear magnetic resonance (2D TD-NMR) characterization of cell wall water of Fagus sylvatica and Pinus taeda L.

A novel partially carbonized Fe3O4@PANI-p catalyst for tetracycline degradation via peroxymonosulfate activation

A novel polyaniline (PANI) partially carbonized core–shell material (Fe3O4@PANI-p) was prepared and used to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. Partial carbonization of the polyaniline layer introduced carbon catalytic sites into the catalyst. The polyaniline/carbon bilayer structure of the catalyst confined the metal oxides in the shell layer, which improved the catalytic performance of the material and reduced the leaching of metal ions. The effect of various influencing factors, such as PMS dosage, pollutant concentration, and initial pH on TC degradation was further investigated. The TC degradation efficiency was positively correlated with PMS dosage and negatively correlated with TC concentration. In the pH range of 3.0–9.0, the degradation efficiency of TC (C0 = 20 mg/L) reached more than 87.0 % within 90 min, and the highest efficiency was 89.8 %. HCO3– promoted the degradation of TC to a higher efficiency (95.9 %), whereas H2PO4− slightly inhibited it (88.1 %). The effect of humic acid (HA) in water on TC degradation was not significant. After three cycles, the degradation efficiency still reached 77.5 % and the degradation efficiency was restored to 83.7 % after pyrolysis regeneration. According to quenching experiments and electron paramagnetic resonance (EPR) characterization, the main reactive oxygen species (ROS) in the degradation process were singlet oxygen (1O2), followed by superoxide radicals (O2·−), sulfate radicals (SO4·−), and hydroxyl radicals (·OH). The above findings provide a reference for the application of new multilayer core–shell composites for antibiotic wastewater treatment.

Electron Paramagnetic Resonance Characterization of Sodium- and Carbonate-Containing Hydroxyapatite Cement.

Ionizing radiation-induced paramagnetic defects in calcified tissues like tooth enamel are indicators of irradiation dose. Hydroxyapatite (HA), the principal constituent in these materials, incorporates a variety of anions (CO32-, F-, Cl-, and SiO44-) and cations (Mn2+, Li+, Cu2+, Fe3+, Mg2+, and Na+) that directly or indirectly contribute to the formation of stable paramagnetic centers upon irradiation. Here, we used an underexploited synthesis method based on the ambient temperature setting reaction of a self-hardening calcium phosphate cement (CPC) to create carbonate-containing hydroxyapatite (CHA) and investigate its paramagnetic properties following γ-irradiation. Powder X-ray diffraction and IR spectroscopic characterization of the hardened CHA samples indicate the formation of pure B-type CHA cement. CHA samples exposed to γ-radiation doses ranging from 1 Gy to 150 kGy exhibited an electron paramagnetic resonance (EPR) signal from an orthorhombic CO2•- free radical. At γ-radiation doses from 30 to 150 kGy, a second signal emerged that is assigned to the CO3•- free radical. We observed that the formation of this second species is dose-dependent, which provided a means to extend the useful dynamic range of irradiated CHA to doses >30 kGy. These results indicate that CHA synthesized via a CPC cement is a promising substrate for EPR-based dosimetry. Further studies on the CHA cement are underway to determine the suitability of these materials for a range of biological and industrial dosimetry applications.

Optimization of Anchor Placement in TPoS MEMS Resonators: Modeling and Experimental Validation

In this paper, a semi-analytical model is derived to calculate the anchor loss of TPoS resonators operating in higher-order length extensional modes. This model provides valuable insights on the effect of order, device dimensions, position and number of anchors on the quality factor (Q) of these resonators. Results from this model are in close agreement with the FEM simulations. The optimum position, dimension, and the number of anchors to deliver the highest Q are also discussed. Predictions of the model are validated through characterization of TPoS resonators fabricated to operate at a resonant frequency of around 1 GHz with different number of anchor pairs and position. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$23^{rd}$ </tex-math></inline-formula> order resonator with a W/L ratio of 1.5 with three pairs of anchors placed at positions suggested by the model gave a loaded Q of 4431, which is 65% more than the conventional case where anchors are uniformly placed towards the edge, and also an improvement in the insertion loss by 5.5 dB compared to the latter. For resonators where the anchor loss is predominant, our results show that the performance can be improved by placing the anchors at the optimum position, closer to the middle of the resonator than the conventional scheme where anchors are uniformly placed towards the edge.

Electromagnetic characterization of mirror symmetric resonator based metamaterial and frequency tuning: a dielectric based multilayer approach

This article presents a novel metamaterial (MTM) with a mirror symmetric resonator that exhibits multiple resonances of transmission coefficient covering the L, S, C, and X bands. The resonating patch is constructed on a low-loss Rogers (RT5880) substrate with a dimension of 20 × 20 × 1.575 mm3. It consists of four equal quartiles with each quartile made with interconnected split-ring resonators; the quartiles are in mirror symmetry with each other. The proposed MTM exhibits resonances at 1.98 GHz, 3.67 GHz, 4.74 GHz, 8.38 GHz, and 10.8 GHz, and electromagnetic characterization is performed through studies of permittivity, permeability, refractive index, and impedances. Power analysis is also performed, and the effect of polarized incident waves is studied. An electromagnetic characterization study reveals that the proposed MTM shows negative permittivity with near-zero permeability and refractive index. It also reveals very little power consumption in the vicinity of the resonances. The dielectric-based frequency tuning is studied by using different dielectric layers over the patch that provides good frequency tuning; this method provides flexibility for adjusting the resonance frequencies in accordance with the application demand. The measured result of the proposed unit cell with the dielectric layer is extracted using a vector network analyzer, and the results exhibit good similarity with the simulated ones. The above-mentioned properties, along with a good effective medium ratio (EMR) of 7.57 indicate that this MTM is suitable for frequency selective applications in microwave devices such as antenna performance improvement and sensing.

Chemical conversion of waste PET to valued-added bis(2-hydroxyethyl) terephthalamide through aminolysis

Polyethylene terephthalate (PET) refers to a widely used thermoplastic polymer that is difficult to degrade naturally. Therefore, large amounts of waste PET need to be recycled. In this study, to achieve a green and efficient method to degrade and recycle waste PET for new functional chemicals, PET waste was first swelled with acetic acid. Then, it was degraded under atmospheric pressure at 70 °C for 4 h using ethanolamine as solvent. The degradation efficiency of PET was higher than conventional methods because of the swelling-induced pores caused by the acetic acid. The aminolysis product bis(2-hydroxyethyl) terephthalamide was confirmed by Fourier transform infrared and nuclear magnetic resonance characterization methods and could be readily separated and recovered from the solvent. Finally, the degradation mechanism was discussed. This research provides a feasible and efficient approach to realize the recycling of PET with high value.

Design of a Scavenging Pyrrole Additive for High Voltage Lithium Ion Batteries

We report 1-(dimethylamino) pyrrole (PyDMA) as an electrolyte additive for high voltage lithium ion batteries based on LiNi0.6Mn0.2Co0.2O2 (NMC622)//Graphite with an upper cutoff voltage of 4.4 V. Density Functional Theory (DFT) modeling indicates that the unique structure of PyDMA could be effective in preventing the hydrolysis of LiPF6 in a carbonate electrolyte, mitigating issues related to HF formation. The calculations also indicated that the additive would oxidize at lower potentials than typical electrolyte solvents, which could lead to protective films at the cathode surface. These expectations were tested using Nuclear Magnetic Resonance (NMR) and extensive electrochemical characterization. NMR studies confirmed the superb dehydrating capability of PyDMA, which successfully prevents HF formation even at high water content. Addition of 0.5 wt% PyDMA resulted in improved capacity retention in full-cells, and also in lower levels of transition metal dissolution from the cathode. Incremental capacity (dQ/dV) analysis indicates that benefits of PyDMA at low concentration (0.5-1 wt%) are associated with decreased rates of Li+-trapping reactions, and that higher concentrations of the additive can lead to isolation of cathode domains. Our study indicates that PyDMA could be a promising electrolyte additive for high voltage lithium ion batteries at a low concentration.

Enhanced removal of phosphonates from aqueous solution using PMS/UV/hydrated zirconium oxide process

Traditional treatment processes cannot completely remove phosphonates in circulating cooling water by one-step method. Herein, we designed peroxymonosulfate/UV irradiation/hydrated zirconium oxide (PMS/UV/HZO) coupling process to enhance the phosphonates removal. In particular, nitrilotris-methylenephosphonic acid (NTMP) removal efficiency by PMS/UV/HZO process was much higher than that of PMS/UV process, UV/HZO process and other processes in comparison experiments. Specifically, almost 97.2% NTMP in water was degraded, and the total phosphorous (TP) reduced from 9.3 mg/L to 0.26 mg/L at pH 7 within 180 min. TP removal efficiency still reached above 90% after 5 cycles adsorption-desorption of HZO. Moreover, Clˉ, NO3ˉ and SO42ˉ ions all had negligible effect on NTMP removal. During the process, NTMP was first destroyed to form phosphates and other intermediates by the reactive oxygen species (ROS), then phosphates were in situ immobilized via HZO adsorption. Sulfate radical (SO4•−) has been confirmed to be the major ROS in the reaction system by quenching experiment and electron paramagnetic resonance (EPR) characterization. And the excellent selective adsorption capacity of HZO for phosphate produced was attributed to the strong inner-sphere coordination between H2PO4ˉ/HPO42ˉ and Zr-OH on the surface of HZO. These results suggest that PMS/UV/HZO process is a promising technique for enhanced phosphonates decontamination.