Phase Regeneration Research Articles

Regeneration of ozone decomposition catalysts by elimination of O22- from oxygen vacancies

The deactivation of ozone decomposition catalysts is a big drawback for its industrial application, and the existing gas phase regeneration methods are not universally applicable while the operability conditions are harsh. Thus, there is a pressing need to develop a mild and universal regeneration approach. Based on the fact that the deactivation of ozone decomposition catalysts is mainly due to the accumulation of O22- in the surface oxygen vacancies, increasing the catalyst metal valence state. Herein, we propose a liquid phase method by elimination of O22- from oxygen vacancies for regenerating inactivated ozone decomposition catalysts. This method worked well for regenerating ozone decomposition catalysts by using the reducing solution with oxidation reduction potential (ORP) less than −163 mV. Experimental results indicate that even after ten cycles of deactivation and regeneration, surficial oxygen vacancies and metal valence states of the ozone decomposition catalyst e.g. MnFe0.25Ox can be well restored and the ozone conversion rate decreased by less than 5 %.

Miniaturizable Phase-Sensitive Amplifier Based on Vector Dual-Pump Structure for Phase Regeneration of PDM Signal

Miniaturizable Phase-Sensitive Amplifier Based on Vector Dual-Pump Structure for Phase Regeneration of PDM Signal

From nickel waste solution to hydrogen storage alloys – An excellent example of circular economy implementation

In light of the need to protect the environment from hazardous heavy metals, waste management is becoming not just a proposal but a necessity for the reduction of wastewater toxicity and, additionally, a value-added substitute for processes of extracting raw materials from primary sources. This article demonstrates the feasibility of using critical and hazardous element as Ni(II) from industrial nickel waste solutions to produce hydrogen storage alloys (HSA), perfectly fulfilling the circular economy assumptions. The hydrometallurgical process proposed for the preparation of the Ni-containing electrolyte (NiE) from the waste solution included the following stages: diffusion dialysis, Cr(III) and Al(III) hydroxide precipitation, extraction to separate Co(II) from Ni(II), and the organic phase regeneration by Co(II) stripping with dialysate. The raffinate after extraction performed as NiE (∼10–15 g/dm3 Ni(II), 0.1 g/dm3 Co(II)) for the preparation of HSA. However, to improve the quality of Ni deposit on NiCo foam or steel plates, NiE should be modified with an ammonia solution (to pH ∼ 12). A better voltammetric characteristic of the modified electrodes (25–30 percentage points higher peaks resulting from NaBH4 electrooxidation), compared to those unmodified was reported. It was proven that the electroactive materials obtained showed high catalytic performance for the borohydride oxidation reaction.

Towards a photonic integrated all-optical phase regenerator.

All-optical phase regeneration aims at restoring the phase information of coherently encoded data signals directly in the optical domain so as to compensate for phase distortions caused by transceiver imperfections and nonlinear impairments along the transmission link. Although it was proposed two decades ago, all-optical phase regeneration has not been seen in realistic networks to date, mainly because this technique entails complex bulk modules and relies on high-precision phase sensitive nonlinear dynamics, both of which are adverse to field deployment. Here, we demonstrate a new, to the best of our knowledge, architecture to implement all-optical phase regeneration using integrated photonic devices. In particular, we realize quadrature phase quantization by exploring the phase-sensitive parametric wave mixing within on-chip silicon waveguides, while multiple coherent pump laser tones are provided by a chip-scale micro-cavity Kerr frequency comb. Multi-channel all-optical phase regeneration is experimentally demonstrated for 40 Gbps QPSK data, achieving the best SNR improvement of more than 6 dB. Our study showcases a promising avenue to enable the practical implementation of all-optical phase regeneration in realistic long-distance fiber transmission networks.

Improving the economical efficiency of a simulated-moving-bed process for biofuel production from agarose in red algae

A four-zone simulated-moving-bed (SMB) process has recently been applied to the recovery of galactose (biofuel-convertible monosugar) from agarose-hydrolysis output, which is part of agarose-based biofuel production process. To substantially improve the economical efficiency of the aforementioned biofuel production process, a new SMB process based on a three-zone advanced mode using fewer columns, pumps, and port-switching valves was proposed in this study. Its configuration and operation strategy were devised in a way to facilitate the complete regeneration of SMB solid phase against highly adsorbed impurities in the agarose-hydrolysis output while enhancing the separation margin between a key-impurity band front and a galactose product port in a feed-loaded separation zone. To investigate the advantages of such proposed SMB over the previous SMB, the two processes were optimized under equal conditions. It was found that the proposed process could significantly outperform the previous process in terms of processing rate, solvent usage, and galactose product yield while being in an advantageous position in the aspects of the equipment and maintenance costs and the potential for further acquisition of an industrially useful side-product. Furthermore, such advantage of the proposed process became greater as the required level of purity or processing rate increased.

Phase Regeneration of QPSK Signals Based on Kerr Soliton Combs

We demonstrate a phase-sensitive and amplification-based all-optical phase regenerator by utilizing on-chip Kerr soliton combs. In the experiment, we demonstrate the direct generation of a Kerr soliton comb in a silicon nitride micro-ring at the receiver side of optical communication systems by applying the transmitted signal as a pump light. The mutual coherence between the signal and the regenerated Kerr comb is excellent, and the all-optical phase regeneration of a 20 GBaud/s QPSK signal is achieved. In contrast to the traditional scheme, our solution shows better SWaP (size, weight, and power) factors. Our study will enhance the relay and reception performance of all-optical communication systems.

Integrated CO2 capture and reduction catalysis: Role of γ-Al2O3 support, unique state of potassium and synergy with copper

Carbon dioxide capture and reduction (CCR) process emerges as an efficient catalytic strategy for CO2 capture and conversion to valuable chemicals. K-promoted Cu/Al2O3 catalysts exhibited promising CO2 capture efficiency and highly selective conversion to syngas (CO + H2). The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites. The present work aims at more precise understanding of the roles of the potassium and copper and the contribution of the metal oxide support. While γ-Al2O3 guarantees high dispersion and destabilisation of the potassium phase, potassium and copper act synergistically to remove CO2 from diluted streams and promote fast regeneration of the active phase for CO2 capture releasing CO while passing H2. A temperature of 350℃ is found necessary to activate H2 dissociation and generate the active sites for CO2 capture. The effects of synthesis parameters on the CCR activity are also described by combination of ex-situ characterisation of the materials and catalytic testing.

Phase regeneration of star-16QAM using phase-sensitive amplification in graphene silicon-based organic hybrid waveguide

We theoretically demonstrate the phase regeneration of the star-16-quadrature-amplitude-modulation(star-16QAM) signal in a graphene-graphene oxide hybrid waveguide. The multi-order dispersion properties of this waveguide are tuned by graphene, where the near-zero-dispersion-point moves to right with increasing applied electrochemistry. The waveguide nonlinearity coefficient is 1.534×106/m/W and the dispersion is flat in the ultra-wide wavelength range of 1310 nm to 1860 nm by filling the waveguide with the high kerr coefficient organic material graphene oxide. The phase regeneration of the star-16QAM signal is achieved by using a dual-conjugate-pump degenerate four-wave mixing (FWM) technique, and the results show that the error-vector -magnitude (EVM) is reduced from 39.25% to 2.14%, the phase noise is effectively compressed.

Boosting efficient and low-energy solid phase regeneration for single crystal LiNi0.6Co0.2Mn0.2O2 via highly selective leaching and its industrial application

The proliferation of energy storage and power devices has led to an explosion in the number of spent batteries needing regeneration or safe and sustainable disposal. However, traditional solid-phase and hydrometallurgical leaching approaches to regeneration are characterized by high energy consumption, long processing routes, and the generation of a lot of waste solvents. To solve these problems, in this paper, we report an efficient and low-energy strategy for regenerating high nickel LiNi0.6Co0.2Mn0.2O2 materials based on selective leaching that is effective even under non-optimal leaching conditions. Leaching repairs the collapsed crystal structure and removes the impurity phases of the spent LiNi0.6Co0.2Mn0.2O2, and the solid–liquid mixture does not need complex treatment, making the process energy-efficient and environmentally friendly. The resynthesized single crystal LiNi0.6Co0.2Mn0.2O2 displays an initial specific discharge capacity of 179.2 mAh·g−1 and retains 90.7% of its capacity at 0.2C after 150 cycles, which is comparable to the performance of commercial materials. This method can accurately replenish the lithium lost from spent materials and repair the damaged crystal structure, improving lithium-ion transport and recycling the spent battery for industrial applications.

Phase regeneration of 8PSK signal using phase-sensitive amplification based on an organic-Ge hybrid waveguide.

We numerically demonstrate the phase regeneration of eight-phase-shift keying (8PSK) in an organic-Ge hybrid waveguide with 10µm length. Through filling graphene oxide with a high Kerr coefficient and engineering of waveguide dimensions, an ultrahigh nonlinear coefficient with 5.86×106W-1m-1 is attained at 1550 nm. The phase regeneration of 8PSK signal is achieved by using phase-sensitive amplification of the dual-conjugated-pump degenerate four-wave mixing scheme. The error-vector magnitude (EVM), optical signal-to-noise ratio, as well as constellation diagrams of 8PSK signal are also used to evaluate the phase regeneration capacity quantitatively. A reduction of EVM from 39.25% to 1.34% for 8PSK signal is found. The results show great phase regeneration and noise-squeezing ability, which indicate that such a phase-sensitive amplifier of a waveguide can find critical promising applications in all-optical signal processing.

Fractionation of Transition Metals by Solvent Extraction and Precipitation from Tannic Acid-Acetic Acid Leachate as a Product of Lithium-Ion Battery Leaching

Solvent extraction and precipitation schemes are applied to isolate copper, cobalt, manganese and nickel from leachate, produced from spent lithium-ion battery leaching using tannic acid-acetic acid as lixiviant. The metal separation and purification were developed based on a ketoxime (LIX® 84-I) and a phosphinic acid (Cyanex® 272) extraction system. Aside from the leachate’s initial pH, which dictates the metal isolation flowsheet, other parameters affecting metal extraction rate, such as phase ratio, extractant concentration, and acid stripping will be evaluated. Copper was selectively removed from leachate at pH 3, using LIX® 84-I 10% v/v followed by cobalt and manganese co-extraction from the raffinate using Cyanex® 272 10% v/v at pH 5. After both metals were stripped using sulfuric acid 0.2 M, manganese was quantitatively precipitated out from the strip solution using potassium permanganate or sodium hypochlorite. Nickel was isolated using LIX® 84-I from raffinate at pH 5, producing a lithium- rich solution for further treatment. No third phase was formed during the extraction, and sulfuric acid was proved suitable for organic phase regeneration.

Potential use of synergist D2EHPA/Cyanex 302 in kerosene system for reactive extraction: Zinc recovery and organic phase regeneration

The extraction of Zn(II) from aqueous solution was studied using extractants mixture in organic base kerosene by reactive extraction. The extraction process was conducted by evaluating some base and synergistic extractants, followed by back-extraction using several types of stripping agents. Around 99% of zinc extraction was achieved at pH 9 using 9 mM D2EHPA as a base and 1 mM Cyanex 302 as a synergistic extractant with a synergistic coefficient of 2.9. Such findings proof to the intensification of reactive extraction compared to the single system. So, the mixture system produced synergistic and productive extraction with minimum use of extractants. The reaction between Cyanex 302-D2EHPA and Zn was studied, and its stoichiometry, as well as the possible structure of Zn(II)-extractant complexes in the extract phase, were investigated. FTIR and the slope analysis method both produced similar findings that Zn•A2•2HB is the zinc form complex with 2 mol D2EHPA (HA) and 2 mol Cyanex 302 (HB) extracted species. Meanwhile, the back-extraction revealed that 0.45 M acidic thiourea is the most effective stripping agent, which achieved almost 100% stripping efficiency. For recycling, the organic phase can be recycled/reused successfully up to 4 times with almost 100% stripping performance.

Sulfur-resistant methane combustion invoked by surface property regulation on palladium-based catalysts

Improving sulfur resistance of palladium-based catalysts is crucial for the sustained and efficient methane combustion. Herein, the surface property of catalysts was rationally tailored to tune the dynamic behavior of sulfur species on active sites and supports, which was qualitatively and quantitatively studied through a combination of in-situ and on-line characterizations. Results reveal that the content of accumulated sulfur species in catalysts increased linearly (0.20–0.59 mmol SO2·g−1) with the rise of the surface basic sites, while it was restrained in catalysts with high surface acidity. The zirconium doped alumina supported palladium catalyst exhibited a moderate surface acidity/basicity, meanwhile it showed an excellent catalytic activity in the presence of SO2 and after regeneration. Its enhanced sulfur resistance derived from the proper interaction between supports and sulfur species, the facile decomposition of zirconium sulfates, the suppressed formation of surface/bulk aluminum sulfates, as well as the effective regeneration of PdO phase. The established quantitative correlation between accumulated sulfur species, surface acidity/basicity and catalytic performance paves the way to develop sulfur-resistant palladium-based catalysts for oxidation reactions.

Boosting Efficient and Low-Energy Solid Phase Regeneration for Single Crystal Lini0.6co0.2mn0.2o2 Via Highly Selective Leaching and its Industrial Application

Boosting Efficient and Low-Energy Solid Phase Regeneration for Single Crystal Lini0.6co0.2mn0.2o2 Via Highly Selective Leaching and its Industrial Application

Mode-division multiplexing phase-sensitive amplification for mode selective and mode equalized phase regenerative amplifications

In this work, mode-division multiplexing (MDM) phase-sensitive amplification (PSA) for all-optical mode selective and mode equalized phase regeneration is presented and investigated. MDM PSA relies on reasonable phase-matching conditions, which makes intramode four-wave mixing in the fiber much stronger than that of cross-mode. It enables multimode signals to interact mainly with the same spatial mode pumps and idlers. Thus, MDM signals can obtain synchronous phase regeneration and avoid cross talk with different mode signals. To achieve this, we designed an appropriate few-mode fiber by an inverse design method based on a neural network for obtaining the desired phase mismatch and low modal dispersion. The results show that effective phase regeneration can be achieved for the degraded 40 Gbit/s binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) signals. For BPSK signals, error vector magnitudes (EVMs) of the regenerated signal on two modes are reduced from − 8.013 d B and − 8.068 d B to − 24.867 d B , and − 26.090 d B , respectively. For QPSK signals, the EVMs are reduced from − 16.767 d B and − 16.583 d B to − 24.867 d B and − 24.822 d B , respectively.

All-optical simultaneous amplitude and phase regeneration for MPSK signal with ASE noise based on two-wave PSA

A phase sensitive amplification (PSA) regeneration model for M-ary phase shift keying (MPSK) signals with amplified spontaneous emission (ASE) noise based on the interference between signal and its (M+1)th harmonic is proposed. Compared with the existing models based on different combinations of signal and harmonics, the new regeneration model is optimal in theory to deal with the MPSK signal degraded by ASE noise. The QPSK format is taken as an example for simulation verification and two existing classic models are also performed with the same parameters for comparison. The regeneration performance is evaluated by input–output constellations, phase and amplitude regeneration factors, and the relay distance at the bit error rate (BER) of 3.8×10−3 by measuring the transmission reach after the regenerator. The results show that the new model has the optimal relay performance for ASE-noise MPSK format, which is promising to be applied in large-capacity, flexible, and reliable optical transport networks.

Effect of treadmill exercise on pain-related Wnt/β-catenin signaling pathway in dorsal root ganglion neurons at the early phase regeneration of the injured sciatic nerve.

The purpose of this study was to determine whether treadmill walking exercise can improve mechanical allodynia through regulation of Wnt/β-catenin signaling in dorsal root ganglion (DRG) neurons at the early stage of regeneration after sciatic nerve injury (SNI). The experimental rats were divided into seven groups: the normal control, sedentary groups for 3-, 7-, and 14-day post crush (dpc), and exercise group for 3, 7, and 14 dpc. The rats in exercise groups performed treadmill walking exercise at a speed of 8 m/min for 20 min once a day according to experiment duration. For evaluating neuropathic pain-like behavior after SNI, the mechanical allodynia was examined by von Frey apparatus. And the expression levels of pain-related protein were identified in the cytoplasm or nucleus of DRG neurons using Western blot techniques. Mechanical allodynia was significantly ameliorated in the exercise group at 7 and 14 dpc. Treadmill exercise further decreased Wnt3a expression at 3, 7, and 14 dpc compared to in the sedentary group. Also, phosphorylated-low-density lipoprotein receptor 6 was decreased in exercise groups at 3 and 14 dpc. Beta-catenin was significantly decreased in exercise groups at 3 and 14 dpc compared to sedentary groups as well as treadmill exercise decreased translocation of β-catenin towards the nucleus of DRG neurons at 14 dpc. Our findings indicate that treadmill walking exercise may be an important regulator of neuropathic pain after peripheral nerve injury through delayed Wnt/β-catenin signaling pathway in DRG neurons.

Electrospun polyvinylpyrrolidone (PVP) hydrogels containing hydroxycinnamic acid derivatives as potential wound dressings

Polyvinylpyrrolidone (commonly known as povidone or PVP) rapidly dissolves in water. This significantly hinders its use in sustained release formulations developed for the biomedical field. Electrospun fibers of PVP dissolve even faster due to larger surface to volume ratio. In this work, we propose a way to circumvent this problem by developing and using functional fibrous materials in hydrogel form. In particular, we demonstrate that ethanolic solutions of PVP containing two hydroxycinnamic acid derivatives, namely p-coumaric and ferulic acids could be electrospun into functional hydrogel fiber mats. After electrospinning, the formed composite mats were first thermally treated at 130 °C for 20 h and subsequently were immersed in aqueous media, where they turned into hydrogels. Thermal annealing did not degrade hydroxycinnamic acid derivatives, preserving their functionality. We propose these hydrogel fiber mats as potential wound dressings and to that end, in vitro tests showed up to 8 days of antioxidants’ release, and consequent protection of A549 epithelial cells against oxidative stresses. Biocompatibility tests using human red blood cells, A549 and HaCaT cell lines indicated no adverse effects. Model studies of mice skin burns induced by UV-B radiation showed that the hydrogel fiber dressings significantly reduced the levels of matrix metallopeptidase, (MMP-9), and glutathione peroxidase 1 (GPX-1), which are usually upregulated by reactive oxidative species on burnt skin. Finally, ex-vivo human skin investigations demonstrated skin regeneration and control of the inflammatory phase as indicated by low levels of pro-inflammatory cytokines (IL-6 and IL-8). Therefore, our outcomes indicate that the developed PVP-based fiber hydrogels, produced using a simple protocol, are promising candidates for active wound dressings.

N-doped carbon nanofibers encapsulated Cu2-xSe with the improved lithium storage performance and its structural evolution analysis

With the porous feature, high aspect ratio and high electronic conductivity, nitrogen-doped one-dimensional carbon nanofibers can effectively shorten ionic transport pathways and enhance the intrinsic electronic conductivity of metal selenides electrodes, showing a great potential as anode material for the next-generation lithium-ion batteries (LIBs). In this work, we have synthesized nitrogen-doped carbon nanofibers encapsulated Cu2-xSe (N-CNFs@Cu2-xSe) with an average particle size of 20 nm, via electrospinning and in-situ selenization process, giving an excellent lithium storage capability. Specifically, such electrodes delivered a specific capacity of 1079.1 mA h g−1 at 0.1 A g−1 after 100 cycles, while 639.4 mA h g−1 at 2 A g−1 after 1000 cycles, exhibiting an ultralong cycle life. The gradually increased capacity was attributed to phase transformation of Cu2-xSe from crystalline to amorphous state, which leads to the capacity improvement from increased capacitive behavior. The in-situ X-ray diffraction harvest at the real time state of battery demonstrated the phase transition of Cu2-xSe with lithium and phase regeneration among cycles, verifying copper selenide has the features of the high reversibility of conversion reaction and superior thermostability. The high capacity and long cycling life of NCNFs@Cu2-xSe make it possible for great application potentials for high-performance lithium-ion batteries.

Plasma-Assisted Catalyst Active Phase Regeneration in Formate-Selective Carbon Dioxide Electroreduction

Electrochemical carbon dioxide conversion to more valuable products such as formate (its protonation leads to formic acid, a versatile liquid fuel) is an appealing approach to mitigating the greenhouse gas emission and storing a surplus of renewable energy, but the catalysts developed to date are typically plagued by rapid deactivation. Catalyst deactivation often results in a very low selectivity, in the form of a multitude of products, including H2, formate, methanol, CO, and hydrocarbons instead of more preferably a single product, which normally originates from CO-induced phase transformation of hydride catalyst active phases (e.g., Pd hydride). This phase transformation is typically manifested by a high sensitivity of Faradaic Efficiency (FE) and catalyst active phase to small changes of potentials, pH, and temperature. Despite recent developments in catalysts for electrochemical CO2 conversion, least effort has been devoted to regenerating catalyst active phases, especially for Pd-based catalysts when they are targeted for converting CO2 to formate. Effective regeneration of the catalyst active phase would allow enhanced efficiency and catalytic activity in CO2 conversion, greater supply of formate as a fuel, and reduced greenhouse effect. To address the above issues, non-thermal plasma has been utilized to regenerate the hydride catalyst active phase by exacting H from water and assisting in H sorption, and thus eliminate the CO-induced phase transformation through the repulsive interaction between CO and H. This work intends to establish a new framework of multi-electron/proton and heterogeneous electrochemical kinetics driven/mediated by free charged species in plasma.