Liquid-phase Method Research Articles

Scalable Structural Coloration of Carbon Nanotube Fibers via a Facile Silica Photonic Crystal Self-Assembly Strategy

The coloration of carbon nanotube (CNT) fibers (CNTFs) is a long-lasting challenge because of the intrinsic black color and chemically inert surfaces of CNTs, which cannot satisfy the aesthetic and fashion requirements and thus significantly restrict their performance in many cutting-edge fields. Recently, a structural coloration method of CNTFs was developed by our group using atomic layer deposition (ALD) technology. However, the ALD-based structural coloration method of CNTFs is expensive, time-consuming, and not suitable for the large-scale production of colorful CNTFs. Herein, we developed a very simple and scalable liquid-phase method to realize the structural coloration of CNTFs. A SiO2/ethanol dispersion containing SiO2 nanospheres with controllable sizes was synthesized. The SiO2 nanospheres could self-assemble into photonic crystal layers on the surface of CNTFs and exhibited brilliant colors. The colors of SiO2 nanoparticle-coated CNTFs could be easily changed by tuning the sizes of SiO2 nanospheres. This method provides a simple, effective, and promising way for the large-scale production of colorful CNTFs.

Platinum-Tellurium Alloy Metallene Toward Formic Acid Oxidation Reaction

Open AccessRenewablesRESEARCH ARTICLES14 Jan 2023Platinum-tellurium alloy metallene towards formic acid oxidation reaction Ya-Nan Li, Qing-Ling Hong, Bo-Qiang Miao, Tian-Jiao Wang, Yu Ding and Yu Chen Ya-Nan Li Google Scholar More articles by this author , Qing-Ling Hong Google Scholar More articles by this author , Bo-Qiang Miao Google Scholar More articles by this author , Tian-Jiao Wang Google Scholar More articles by this author , Yu Ding Google Scholar More articles by this author and Yu Chen Google Scholar More articles by this author https://doi.org/10.31635/renewables.022.202200005 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Engineering the composition and/or morphology is highly effective strategy for enhancing the electrocatalytic performance of noble metal nanocrystals. Recently, metallenes with specific chemical and physical properties have attracted increasing attention in electrocatalysis field. In this work, two-dimensional ultrathin platinum-tellurium alloy metallene (PtTe A-ML) is synthesized by using a conventional liquid-phase chemical reduction method. The high atom utilization as well as alloy effect endow PtTe A-ML with preeminent electrocatalytic activity for the formic acid oxidation reaction (FAOR). Specifically, the direct oxidation pathway of FAOR can be completely achieved at PtTe A-ML, which suppresses the production of toxic carbon monoxide (CO) intermediates and improves the reaction kinetics of FAOR. Accordingly, the FAOR activity of PtTe A-ML in acidic media is 43 and 5.6 times higher than that of commercial Pt and Pd nanocrystals, respectively. Meanwhile, PtTe A-ML exhibits also excellent electrocatalytic activity for CO oxidation reaction because of the introduction of oxygenophilic Te atoms and electron transfer between Pt and Te, which elevates the durability of PtTe A-ML for FAOR. The study provides a simple synthesis strategy of PtTe A-ML and shows PtTe A-ML has a promising practical prospect in direct formic acid fuel cells. Download figure Download PowerPoint Next article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2023 Chinese Chemical Society Downloaded 4 times PDF downloadLoading ...

Microwave drying method investigation for the process and kinetics of drying characteristics of high-grade rutile TiO2

Titanium dioxide has been extensively applied in aviation, cosmetics, the chemical industry, and coatings. Currently, the primary way to prepare high-grade rutile TiO2 is the chlorination method, which mainly uses ilmenite or titanium slag as raw material through the chlorination process and then reacts it in an oxidation furnace to prepare titanium powders. However, the TiO2 material produced by the liquid-phase method contains a large amount of water, which makes the equipment vulnerable to corrosion in the subsequent process. Meanwhile, the sharp temperature change will lead to the accumulation of water vapor, which may lead to explosion and severe agglomeration, resulting in high research costs and reduced product performance. Therefore, drying equipment with high drying efficiency, high product quality, and low carbon is urgently needed. This paper used microwave drying equipment to assist in drying rutile TiO2 powders. Results indicated that the microwave power, moisture content, and initial mass positively related to the drying rate. The drying process was simulated and analyzed using four common thin-layer kinetic models. A good agreement was that the Modified Page model was in good agreement with the actual drying process of TiO2. The effective diffusion coefficient was calculated. After calculation, the activation energy of microwave-drying TiO2 was 8.22 g/W. This article offers a kinetic theoretical basis and abundant data guidelines for actual products to reinforce the drying of high-grade TiO2 powders.

Removal of Hexavalent Chromium in Aqueous Solution by Cellulose Filter Paper Loaded with Nano-Zero-Valent Iron: Performance Investigation and Numerical Modeling.

Cr(VI) pollution in water bodies is very harmful to human health and the environment. Therefore, it is necessary to remove Cr(VI) from water. In this study, the composite (FP-nZVI) was prepared by loading nano-zero-valent iron (nZVI) onto cellulose filter paper (FP) using a liquid-phase reduction method to improve the dispersibility and oxidation resistance of nZVI. In batch experiments, the effects of iron loading of FP-nZVI, initial concentration of Cr(VI), temperature, and pH on Cr(VI) removal were particularly investigated. The maximum removal rate of 98.6% was achieved at 25 °C, pH = 5, initial concentration of Cr(VI) of 20 mg/L, and FeCl3·6H2O solution concentration of 0.8 mol/L. The removal of Cr(VI) by FP-nZVI conformed to a pseudo-second-order kinetic model and Langmuir isotherm model. The mechanism of Cr(VI) removal was a multi-step removal mechanism, involving adsorption, reduction, and coprecipitation. Column experiments investigated the effect of flow rate (1 mL/min, 3 mL/min, and 5 mL/min) on Cr(VI) removal. We found that increasing flow rate slightly decreased the removal rate of Cr(VI). The transport of Cr(VI) in composite porous media was simulated using HYDRUS-1D, and the results show that the two-site model can well simulate the reactive transport of Cr(VI). This study may provide a useful reference for the remediation of groundwater contaminated with Cr(VI) or other similar heavy metals using FP-nZVI.

Simultaneous fluorescence sensing of vitamin B2 and sulfur ions based on fluorescent copper nanoparticles

In this study, the F-CuNPs were synthesized by a modified liquid-phase chemical reduction method. Throughout the preparation process, anhydrous copper sulfate was used as the copper source, and ascorbic acid in the NaOH solution served as the reducing and protective agent. Förster resonance energy transfer (FRET) may exist between F-CuNPs and vitamin B2 due to the large spectral overlap between the fluorescence emission spectra of F-CuNPs and the UV–vis absorption spectra of vitamin B2. Therefore, the detection of vitamin B2 was designed based on a FRET system between F-CuNPs and vitamin B2. With S2− into the F-CuNPs&VB2 system, the fluorescence intensity of vitamin B2 was quenched, while the fluorescence intensity of F-CuNPs was almost unchanged. There may be a specific reaction between S2− and vitamin B2. Therefore, the research system can be further used to detect S2− based on ratiometric fluorescent probe. The research findings show that the linear range of vitamin B2 was 0.51 nM–34.64 nM with a detection limit of 0.25 nM (S/N = 3), the linear range of S2− was 0.64 μM–60.00 μM with a detection limit of 0.32 μM (S/N = 3). Furthermore, the simultaneous fluorescent sensing system has high sensitivity and selectivity. Therefore, this system was designed and successfully used to detect the content of vitamin B2 and S2− in actual samples to find a new effective method to detect analytes.

Effect of different exfoliation solvents on the saturable absorption properties of germanene and silicene nanosheets prepared by the liquid-phase exfoliation

Germanene and silicene, as graphene analogs of germanium and silicon, have similar structures and properties to graphene, exhibiting exciting nonlinear optical absorption properties. Herein, 2D germanium nanosheets and 2D silicon nanosheets were successfully prepared by liquid-phase exfoliation method using ethanol, isopropanol, and N-methylpyrrolidone as exfoliation solvents, respectively. The dual-arm detection technique was used to systematically research the saturable absorption properties of the nanosheets prepared with different exfoliation solvents from the same material under the excitation of a picosecond pulsed laser. The nonlinear experiment results show that the saturable absorption properties of 2D germanium nanosheets and 2D silicon nanosheets are affected by different exfoliation solvents, and these influences from different exfoliation solvents have their advantages and disadvantages. In addition, the difference in saturable absorption properties of germanium nanosheets and silicon nanosheets under the same experimental conditions is compared. The saturable absorption behavior of germanium nanosheets in the near-infrared band is better than that in the visible band, while the silicon nanosheets have stronger saturable absorption behavior in the visible band. Both germanium nanosheets and silicon nanosheets exhibit superior SA properties, which have a wide range of application prospects in generating ultrashort pulses in ultrafast lasers as saturable absorbers. Our work provides a new idea for the study of nonlinear absorption properties of 2D materials and provides a reference and basis for further optimization and improvement of the properties parameters of saturable absorbers. Additionally, it inspires further research on the nonlinear absorption properties of semiconductor materials.

Ambient Electrosynthesis of Urea with Nitrate and Carbon Dioxide over Iron-Based Dual-Sites.

The development of efficient electrocatalysts to generate key *NH2 and *CO intermediates is crucial for ambient urea electrosynthesis with nitrate (NO3 - ) and carbon dioxide (CO2 ). Here we report a liquid-phase laser irradiation method to fabricate symbiotic graphitic carbon encapsulated amorphous iron and iron oxide nanoparticles on carbon nanotubes (Fe(a)@C-Fe3 O4 /CNTs). Fe(a)@C-Fe3 O4 /CNTs exhibits superior electrocatalytic activity toward urea synthesis using NO3 - and CO2 , affording a urea yield of 1341.3±112.6 μg h-1 mgcat -1 and a faradic efficiency of 16.5±6.1 % at ambient conditions. Both experimental and theoretical results indicate that the formed Fe(a)@C and Fe3 O4 on CNTs provide dual active sites for the adsorption and activation of NO3 - and CO2 , thus generating key *NH2 and *CO intermediates with lower energy barriers for urea formation. This work would be helpful for design and development of high-efficiency dual-site electrocatalysts for ambient urea synthesis.

Remediation and its biological responses to Cd(II)-Cr(VI)-Pb(II) multi-contaminated soil by supported nano zero-valent iron composites

Multi-metal contaminated soil has received extensive attention. The biochar and bentonite-supported nano zero-valent iron (nZVI) (BC-BE-nZVI) composite was synthesized in this study by the liquid-phase reduction method. Subsequently, the BC-BE-nZVI composite was applied to immobilize cadmium (Cd), chromium (Cr), and lead (Pb) in simulated contaminated soil. The simultaneous immobilization efficiencies of Cd, Cr(VI), Crtotal, and Pb were achieved at 70.95 %, 100 %, 86.21 %, and 100 %, respectively. In addition, mobility and bioavailabilities of Cd, Cr, and Pb were significantly decreased and the risk of iron toxicity was reduced. Stabilized metal species in the contaminated soil (e.g., Cd(OH)2, Cd-Fe-(OH)2, CrxFe1-xOOH, CrxFe1-x(OH)3, PbO, PbCrO4, and Pb(OH)2) were formed after the BC-BE-nZVI treatment. Thus, the immobilization mechanisms of Cd, Cr, and Pb, including adsorption, reduction, co-precipitation, and complexation co-exist with the metals. More importantly, bacterial richness, bacterial diversity, soil enzyme activities (dehydrogenase, urease, and fluorescein diacetate hydrolase), and microbial activity were enhanced by applying the BC-BE-nZVI composite, thus increasing the soil metabolic function. Over all, this work applied a promising procedure for remediating multi- metal contaminated soil by using the BC-BE-nZVI composite.

Galvanostatic stimulated Na3Mn2(P2O7)(PO4) as a high-voltage cathode material for aqueous zinc-ion batteries

To meet the application requirements of different scenarios, expanding the selection of cathode materials is a crucial step for the development of aqueous zinc-ion batteries (AZIBs). Manganese phosphates are a type of important and representative cathodes for rechargeable batteries, but they are rarely reported in AZIBs due to their electrochemical sluggishness in aqueous zinc electrolyte. Herein, carbon coating technic and galvanostatic stimulation process are combined to solve the issue and obtain an electrochemically active Na3Mn2(P2O7)(PO4) as cathode material for AZIBs. Carbon coated Na3Mn2(P2O7)(PO4) (NMPP@C) is synthesized by using a liquid-phase method assisted with freeze-drying process. After galvanostatic stimulation (100 mA g−1 for 5 cycles and following at 10 mA g-1), the originally inactive NMPP@C cathode shows a peak capacity of 150 mAh g-1 and then stabilizes at 90 mAh g−1 with a discharge plateau at 1.45 V vs. Zn2+/Zn. It is found that the NMPP@C cathode undergoes a structural decomposition during stimulation process, then α-MnO2 and Zn2P2O7•5H2O jointly serve as electrochemical reaction agents eventually. The electron/proton host (α-MnO2) and the Zn2+ host (Zn2P2O7•5H2O) are generated from the same conductive matrix of NMPP@C, which guarantees a satisfactory rate ability and a decent cycle performance in AZIBs.

Physicochemical properties of different crystal forms of manganese dioxide prepared by a liquid phase method and their quantitative evaluation in capacitor and battery materials.

Although there are many studies on the preparation and electrochemical properties of the different crystal forms of manganese dioxide, there are few studies on their preparation by a liquid phase method and the influence of their physical and chemical properties on their electrochemical performance. In this paper, five crystal forms of manganese dioxide were prepared by using manganese sulfate as a manganese source and the difference of their physical and chemical properties was studied by phase morphology, specific surface area, pore size, pore volume, particle size and surface structure. The different crystal forms of manganese dioxide were prepared as electrode materials, and their specific capacitance composition was obtained by performing CV and EIS in a three-electrode system, introducing kinetic calculation and analyzing the principle of electrolyte ions in the electrode reaction process. The results show that δ-MnO2 has the largest specific capacitance due to its layered crystal structure, large specific surface area, abundant structural oxygen vacancies and interlayer bound water, and its capacity is mainly controlled by capacitance. Although the tunnel of the γ-MnO2 crystal structure is small, its large specific surface area, large pore volume and small particle size make it have a specific capacitance that is only inferior to δ-MnO2, and the diffusion contribution in the capacity accounts for nearly half, indicating it also has the characteristics of battery materials. α-MnO2 has a larger crystal tunnel structure, but its capacity is lower due to the smaller specific surface area and less structural oxygen vacancies. ε-MnO2 has a lower specific capacitance is not only the same disadvantage as α-MnO2, but also the disorder of its crystal structure. The tunnel size of β-MnO2 is not conducive to the interpenetration of electrolyte ions, but its high oxygen vacancy concentration makes its contribution of capacitance control obvious. EIS data shows that δ-MnO2 has the smallest charge transfer impedance and bulk diffusion impedance, while the two impedances of γ-MnO2 were the largest, which shows that its capacity performance has great potential for improvement. Combined with the calculation of electrode reaction kinetics and the performance test of five crystal capacitors and batteries, it is shown that δ-MnO2 is more suitable for capacitors and γ-MnO2 is more suitable for batteries.

Li10GeP2S12 solid electrolytes synthesised via liquid-phase methods.

Li10GeP2S12 solid electrolytes for all-solid-state batteries were synthesised through liquid-phase shaking, which is a suspension synthesis method, in 1 d. Additionally, Li10GeP2S12 solid electrolytes were prepared in 7.5 h, which is the fastest synthesis time, through solution synthesis using excess sulfur and a mixed solvent of acetonitrile, tetrahydrofuran, and ethanol. These Li10GeP2S12 solid electrolytes exhibited an ionic conductivity of 1.6 × 10-3 S cm-1, which is the highest ionic conductivity of previous studies of liquid phase synthesis. Therefore, Li10GeP2S12 solid electrolytes with high ionic conductivity can be rapidly synthesised via liquid-phase methods.

The effects of calcination on the electrochemical properties of manganese oxides.

Three different crystalline forms of Mn3O4 were successfully prepared by a liquid phase method with different additives. Using XRD, SEM, EDS, BET, compacted density and electrochemical analysis, the effects of different additives on the morphology, phase composition, surface characteristics, specific surface area, electrochemical and other physical and chemical properties of manganese oxides were investigated. The results showed that the rod type Mn3O4 was prepared by mixing ammonia water and anhydrous ethanol in a 1 : 1 ratio and an appropriate amount of cetylmethyl ammonium bromide as the additive. The rod-type Mn3O4 showed a maximum specific surface area of 63.87 m2 g-1 and has the advantages of low compaction density, no introduction of other impurities, and high adsorption potential. It also has excellent electrochemical performance and an impedance of 240 Ω. The specific capacity was as high as 666.5 mA h g-1 at 1C current density and 382.2 mA h g-1 after 200 cycles. The results also showed that the electrochemical performance of Mn2O3 prepared at 700 °C from the rod-type Mn3O4 was the best. When it was used as the anode material of a lithium-ion battery, it showed a high specific capacity of 712.1 mA h g-1 after 200 cycles. Therefore, the rod-type Mn2O3 material has the characteristics of high capacity, low cost and environmental friendliness and is a promising candidate anode material for lithium-ion batteries.

Method of Liquid-Phase Fluorination of Polymers to Increase the Selectivity of the Air Separation

The one-sided modification of homogeneous polymer films of polyvinyltrimethylsilane (PVTMS), poly(2,6-dimethylphenyl-1,4 oxide) (PPO), and polybenzodioxane (PIM-1) was carried out by liquid-phase fluorination method using a fluorine-nitrogen mixture in perfluorodecalin. The fluorination time ranged from 10 to 60 min. For PPO films the amorphous and β-nanocrystalline phase (48%) was found by X-ray diffraction analysis of the original films. It was shown that fluorination does not significantly affect the degree of PPO crystallinity. The effect of fluorination time on the effective coefficients of permeability, diffusion, and solubility of oxygen and nitrogen has been studied. It was found that the fluorination leads to a decrease in both effective diffusion coefficients and effective gas solubility coefficients, while the resulting increase in permeability selectivity ranged from 30% for PVTMS to a 2 times increase in the case of PPO and PIM-1. It has been noted that this improvement in permeability selectivity is achieved mainly by the solubility selectivity increasing. The permeability of O2/N2 mixture for original and modified films was studied. It was found that the achieved values of the separation factors are close to the ideal selectivity. The results obtained demonstrate the possibility of effective application of the liquid-phase modification method not only for the homogeneous polymer films of the studied polymers treatment, but also for membranes with a selective non-porous layer based on them.

SYNTHESIS OF DEUTERIUM-LABELED PYRROLYLCARNOSINE

The effect of temperature on the effectiveness of the introduction of deuterium into pyrrolylcarnosine (PC) has been studied. Deuterium gas and heavy water were used as a source of deuterium. Isotope exchange was carried out using solid-phase and liquid-phase methods. It was found that it is better to use isotope exchange with deuterated water to obtain preparative amounts of labeled pyrrolylcarnosine. When using the solid-phase method, the main label is in pyrrole. The inclusion of deuterium at a higher temperature occurs more evenly. In addition, the use of deuterated water made it possible to reduce the amount of unlabeled isotopomer to almost 0%, obtain a product with a yield of 70% and a content of more than 7 deuterium atoms. It is established that the content of deuterium in the substance can be increased by pretreating the reaction mixture with deuterium gas. This approach opens up additional opportunities for synthesis of labeled compounds.

Effect of the calcination temperature on the characteristics of Ni/Fe-oxide electrocatalysts for application in anion exchange membrane electrolysers

Ni–Fe oxides were prepared by the oxalate pathway and heat-treated at three different temperatures. An outstanding performance was achieved in AEMWE by NiFeOx 450-anode-based MEA.

Platinum-palladium-on-reduced graphene oxide as bifunctional electrocatalysts for highly active and stable hydrogen evolution and methanol oxidation reaction.

In the context of the gradual depletion of global fossil fuel resources, it is increasingly necessary to explore new alternative energy. Hydrogen energy has attracted great interest from researchers because of its green and pollution-free characteristics. Moreover, the methanol oxidation reaction (MOR) can combine the hydrogen evolution reaction (HER), replacing the anode reaction (oxygen evolution reaction-OER) in overall water splitting and efficiently producing hydrogen. In this study, platinum-palladium nanoparticles on reduced graphene oxide (PtPd/rGO) were successfully synthesized as HER and MOR bifunctional electrocatalysts under alkaline conditions by the stepwise loading of Pt and Pd bimetallic nanoparticles on rGO using a simple liquid-phase reduction method. PtPd/rGO-2 with 0.99 wt% Pt and 2.86 wt% Pd in the HER has the lowest overpotential (87.16 mV at 100 mA cm-2), with the smallest Tafel slope (18.9 mV dec-1). The exceptional mass activity of PtPd/rGO-2 in the MOR reaches 10.75 A mg-1PtPd, which is 18.22 and 53.75 times greater than that of commercial Pt/C (Pt/C) and commercial Pd/C (Pd/C), respectively. PtPd/rGO-2 is 0.935 V lower in the coupling reaction of HER and MOR (MOR ∥ HER) compared to the overall water splitting (OER ∥ HER) without methanol (10 mA cm-2). This is probably because appropriate Pt and Pd loading exposes many more catalytic sites, and the synergistic interaction between Pt, Pd, and Pt-Pd enhances the catalytic performance. This strategy can be used for the synthesis of novel bifunctional electrocatalysts.

2D MoS2/BiOBr van der Waals heterojunctions by liquid-phase exfoliation as photoelectrocatalysts for hydrogen evolution.

As a semiconductor used for the photocatalytic hydrogen evolution reaction (HER), BiOBr has received intensive attention in recent years. However, the high recombination of photoexcited charge carriers results in poor photocatalytic efficiency. The combination with other photoactive semiconductors might represent a valuable approach to deal with the intrinsic limitations of the material. Given that BiOBr has a 2D structure, we propose a simple liquid-phase exfoliation method to peel BiOBr microspheres into few-layer nanosheets. By tuning the weight ratio between the precursors, we prepare a series of 2D MoS2/BiOBr van der Waals (vdW) heterojunctions and study their behaviour as (photo)electrocatalysts for the HER, finding dramatic differences as a function of weight composition. Moreover, we found that pristine 2D BiOBr and the heterojunctions, with the exception of the 1% MoS2/BiOBr composition, undergo photocorrosion, with BiOBr being reduced to metallic Bi. These findings provide useful guidelines to design novel 2D material-based (photo)electrocatalysts for the production of sustainable fuels.

Inkjet-printed h-BN memristors for hardware security.

Inkjet printing electronics is a growing market that reached 7.8 billion USD in 2020 and that is expected to grow to ∼23 billion USD by 2026, driven by applications like displays, photovoltaics, lighting, and radiofrequency identification. Incorporating two-dimensional (2D) materials into this technology could further enhance the properties of the existing devices and/or circuits, as well as enable the development of new concept applications. Along these lines, here we report an easy and cheap process to synthesize inks made of multilayer hexagonal boron nitride (h-BN)-an insulating 2D layered material-by the liquid-phase exfoliation method and use them to fabricate memristors. The devices exhibit multiple stochastic phenomena that are very attractive for use as entropy sources in electronic circuits for data encryption (physical unclonable functions [PUFs], true random number generators [TRNGs]), such as: (i) a very disperse initial resistance and dielectric breakdown voltage, (ii) volatile unipolar and non-volatile bipolar resistive switching (RS) with a high cycle-to-cycle variability of the state resistances, and (iii) random telegraph noise (RTN) current fluctuations. The clue for the observation of these stochastic phenomena resides on the unpredictable nature of the device structure derived from the inkjet printing process (i.e., thickness fluctuations, random flake orientations), which allows fabricating electronic devices with different electronic properties. The easy-to-make and cheap memristors here developed are ideal to encrypt the information produced by multiple types of objects and/or products, and the versatility of the inkjet printing method, which allows effortless deposition on any substrate, makes our devices especially attractive for flexible and wearable devices within the internet-of-things.

Влияние условий проведения синтеза на физико-химическое свойства ксерогелей, нанопорошков и керамических материалов в системе СеО2 – Nd2O3

By liquid-phase methods of synthesis: by the method of co-precipitation of hydroxides and co-crystallization of nitrate salts, highly dispersed mesoporous powders of the composition are synthesized: (SeO2)1 – x(Nd2O3)x (х = 0,05; 0,10; 0,15; 0,20, 0,25), having a specific pore volume of 0.030 – 0.111 cm3/g and a specific surface area of 7.40 – 119.26 m2/g. Based on them, ceramic nanomaterials of a given composition with CSR ~ 69 – 88 nm (1300 °С) were obtained. The physicochemical properties of the resulting ceramics have been studied; it was revealed that it is a solid solution with open porosity in the range of 17 – 30 %, high values of relative density of 89 – 96 %. In terms of their physicochemical properties (density, thermal expansion coefficient), the resulting ceramic materials are promising as solid oxide electrolytes for medium-temperature fuel cells.

Analysis of Methamphetamine in Urine by HPLC with Solid-Phase Dispersive Extraction and Solid-Phase Fluorescence Derivatization.

We have developed a fluorescence detection-liquid chromatography (HPLC-FL) method that involves sample pretreatment by solid-phase dispersive extraction (SPDE) and solid-phase fluorescence derivatization for the simple and rapid analysis of methamphetamine (MA) in urine. This method uses a reversed-phase polymeric solid-phase gel to clean up analytes in SPDE, followed by fluorescence derivatization with 9-fluorenylmethyl chloroformate (FMOC) in the solid-phase. The optimal conditions for SPDE and solid-phase fluorescence derivatization were obtained when J-SPEC PEP was used as the solid-phase gel and 0.5 mmol/L FMOC in 50 mmol/L borate buffer solution (pH 10) was used as the fluorescence derivatization reagent. The recovery experiment of MA in urine yielded a clean chromatogram with no interfering peaks, demonstrating the validity of our method; the recoveries were 83.6% when spiked at a low concentration level (100 ng/mL) and 80.7% when spiked at a high concentration level (1000 ng/mL). Compared with the conventional liquid-phase method, the reaction product (FMOC-MA) of solid-phase fluorescence derivatization had higher stability. Reaction rate constants were calculated by changing the temperature conditions, and physicochemical parameters, including activation energy and activation entropy involved in the degradation reaction, were obtained from the Arrhenius plot and analyzed thermodynamically. Taken together, our results suggest that the HPLC-FL method with SPDE and solid-phase fluorescence derivatization for sample pretreatment provides a simple and rapid means of analyzing MA in urine samples.