Rapid optimized separation of bromide in serum samples with capillary zone electrophoresis by using glycerol as additive to the background electrolyte

After decades of neglect, bromide has recently been re-introduced in therapy as an effective anti-epileptic drug. The present paper describes the methodological optimization and validation of a method based on capillary zone electrophoresis for the rapid determination of bromide in serum using a high-viscosity buffer and a short capillary (10 cm). The optimized running buffer was composed of 90 mM sodium tetraborate, 10 mM sodium chloride, pH 9.24 and 25% glycerol. The separation was carried out at 25 kV at a temperature of 20 °C. Detection was by direct UV absorption at 200 nm wavelength. The limit of detection (signal-to-noise ratio = 5) in serum was 0.017 mM. The precision of the method was verified in blank serum samples spiked with bromide, obtaining intra-day and day-to-day tests, relative standard deviation values ≤0.2% in terms of migration times and values <2% in terms of peaks areas, respectively.     

Ultrasound-assisted fast encapsulation of metal microparticles in SiO2 via an interface-confined sol-gel method

Although the traditional Stoˇber process-based methods are widely used for encapsulation of metal nanoparticles in SiO₂, these time-consuming methods are not effective for coating metal microparticles with a uniform SiO₂ layer of desired thickness. Herein, an ultrasound-assisted, interface-confined sol–gel method is proposed for fast encapsulation of metal microparticles in SiO₂, and the encapsulation of Sn microparticles is chosen as an example to illustrate its feasibility. The proposed method involves covering metal microparticles with liquid films that contain water, alcohol, surfactant (Span-80) and catalyst (NH₄F) and then ultrasonically dispersing these particles into cyclohexane, where tetraethylorthosilicate (TEOS) is added. To ensure the hydrolysis-condensation reactions of TEOS occurring at the particle-cyclohexane interface so that the formed SiO₂ is coated on the particles, the microparticles should be well dispersed into cyclohexane with the liquid films being not broken away from their surfaces. It is found that the assistance of probe sonication and the addition of surfactant are crucial to achievement of a good dispersion of metal microparticles in cyclohexane. And using high-viscosity alcohol (namely glycerol), controlling the volume ratio of water to alcohol and the amount of water, and choosing a suitable ultrasonic power are essential for preventing the formation of free SiO₂ (namely SiO₂ that is not coated on the particles), which is a result that the liquid films escape from the particle surfaces under ultrasonic cavitation. Our results have also revealed that the thickness of SiO₂ layer can be adjusted by changing the reaction time or the total amount of water. In particular, the thickness of SiO₂ layer can be easily raised by simply repeating the encapsulation procedure. Compared with the traditional Stoˇber process-based methods, the proposed method is time-saving (reaction time: about 30 min vs. more than 12 h) and extremely effective for coating microparticles with a continuous, uniform SiO₂ layer of desired thickness.     

Addendum to “Volumetric properties of binary liquid-phase mixture of (water + glycerol) at temperatures of (278.15 to 323.15) K and pressures of (0.1 to 100) MPa” [J. Chem. Thermodyn. 79 (2014) 135–158]: Effect of pressure on excess thermodynamic characteristics of mixture water + glycerol

Experimentally determined volumetric properties of the liquid binary mixture of {water (1) + glycerol (2)} were processed to calculate the changes of the following thermodynamic parameters with pressure: excess molar Gibbs free energy, ${\mathrm{\Delta }}_{P_o\to P}{G}_m^E$, excess molar entropy, ${\mathrm{\Delta }}_{P_o\to P}{S}_m^E$, excess molar enthalpy, ${\mathrm{\Delta }}_{P_o\to P}{H}_m^E$, as well as the enthalpy of mixing of water and glycerol, $H_m^E$, at 100 MPa. The mixing enthalpies of water and glycerol, $H_m^E$, became more exothermic with pressure increasing at all temperatures studied.     

载体表面酸碱性质对无碱水溶液中Au催化的甘油氧化反应产物选择性的调控作用

甘油(GL)是一种重要的生物平台分子,通过催化选择氧化反应将其转化为具有高附加值化学品是可持续发展化学化工的重要课题之一.以Au为催化剂的GL水相选择氧化反应可以生成甘油酸(GLA)、二羟基丙酮(DHA)、羟基丙二酸(TTA)、羟基乙酸(GCA)和乳酸(LA)等多种产物.通常,该反应需要碱(NaOH)存在时才能进行,产物往往以GLA为主(选择性40%-70%),副产物主要有GCA, TTA和草酸(OA).一般认为,可溶性碱(OH-)是通过夺取GL分子中羟基上的质子而诱发反应的.尽管在Au催化的反应体系中从未检测到有甘油醛(GLD)生成, GLD和/或DHA被认为是该反应的中间物种.本课题组前期工作表明,氧化物(TiO2, Al2O3, ZrO2, CuO等)负载的纳米Au催化剂能够在无碱(无外加OH-)水溶液中选择性催化GL氧化生成DHA(而不是GLA).因此, OH-的存在与否很可能会改变水溶液中Au催化剂上GL氧化反应的途径.本文试图回答当GL的水溶液中不存在NaOH时, Au催化剂载体的表面酸碱性质是否也会对GL氧化反应的选择性产生调控作用.我们选用Mg/Al比(x)不同的MgO-Al2O3样品为Au催化剂的载体,以尿素为沉淀剂,采用沉积沉淀法制备了相应的Au/MgO-Al2O3(x)催化剂样品.采用X射线衍射、电感耦合等离子体-原子发射光谱仪、透射电镜以及N2吸附-脱附等温线等对MgO-Al2O3(x)和/或Au/MgO-Al2O3样品的物相、元素组成、Au颗粒大小以及比表面积等进行了表征分析;采用NH3和CO2程序升温脱附(TPD)分别对MgO-Al2O3(x)载体表面的酸、碱性进行了测定. NH3-TPD和CO2-TPD结果表明,随着Mg/Al比x从0增加至4.8, MgO-Al2O3(x)的表面酸量从0.94降到0.20μmol/m2,而其表面碱量却从0.05剧增至0.80μmol/m2.因此,载体中MgO含量越多或Mg/Al比越大,其酸性越弱而碱性越强.在无碱水溶液中的催化反应结果表明, Au/MgO-Al2O3(x)上GL氧化反应的主要产物为DHA, GLA以及GCA等.随着x值(催化剂表面碱性)不断增大,产物DHA的选择性从约80%下降到10%左右,而GLA的选择性却从约4%增加至约50%.当载体为酸性最强的Al2O3(x =0)时,产物DHA的选择性为最高(80%).由此可见,载体表面的酸碱性质决定了无碱水溶液中Au催化剂上的GL氧化产物的分布. 此外,当保持Au粒子的尺寸基本不变(如3.1或6.6 nm左右),而改变载体的酸碱性质时, Au/MgO-Al2O3催化GL氧化反应的活性(TOF)可相差8-9倍.本文还通过改变Au/MgO-Al2O3样品焙烧温度,制备了表面酸碱性质相同而颗粒大小不同的三个Au/MgO-Al2O3(0.2)催化剂,考察了Au粒径对GL氧化反应选择性的影响.在这三个催化剂上, Au颗粒的平均尺寸分别为2.8,3.2和6.6 nm, GL氧化反应的产物选择性近乎相同(DHA和GLA的选择性分别为65%和15%左右),但平均尺寸为6.6 nm Au粒子的催化活性(TOF)是3.2 nm Au粒子的1.6倍,2.8 nm Au粒子的2.7倍.因此,本文建立了载体表面酸碱性质与无碱水溶液中GL氧化产物选择性之间的关系,通过改变载体表面酸碱性质实现了对无碱水溶液中Au催化剂上GL氧化反应选择性的调控.尽管载体酸碱性质和Au粒子尺寸都对Au/MgO-Al2O3催化剂的本征活性有重要影响,但载体酸碱性质的影响更显著.     

VLE of CO2 + glycerol + (ethanol or 1-propanol or 1-butanol)

Vapour-liquid equilibrium of CO₂ + [0.00871 glycerol + 0.99129 (ethanol or 1-propanol or 1-butanol)] mixtures was measured at the temperatures of 313.15 K and 333.15 K, and close to the critical line, at pressures up to 12 MPa. On the liquid side, the bubble points measured for these ternary mixtures follow closely the behaviour of VLE reported by several authors for the corresponding binary mixtures without glycerol. On the vapour side, however, dew points for the ternary mixtures deviate significantly from VLE results for the binaries. A correlation of the results obtained for the CO₂ + glycerol + ethanol mixture with the Peng-Robinson equation of state, admitting quasi-binary behaviour, equally yields good agreement on the liquid side, and significant deviations on the vapour side.     

Synthesis of (Z)-organylthioenynes using KF/Al2O3/solvent as recyclable system

PEG-400 and glycerol were successfully used as recyclable solvents for the synthesis of several organylthioenynes in good to excellent yields and high selectivity using solid supported catalyst (KF/Al₂O₃). This easy, general and improved method furnishes the corresponding alkenyl sulfides preferentially with Z configuration. The catalytic system and the glycerol or PEG-400 can be reused up to three times without previous treatment with comparable activity.     

Valorization of Rice Straw via Hydrotropic Lignin Extraction and Its Characterization

Rice straw hydrotropic lignin was extracted from p-Toluene sulfonic acid (p-TsOH) fractionation with a different combined delignification factor (CDF). Hydrotropic lignin characterization was systematically investigated, and alkaline lignin was also studied for the contrast. Results showed that the hydrotropic rice straw lignin particle was in nanometer scopes. Compared with alkaline lignin, the hydrotropic lignin had greater molecular weight. NMR analysis showed that β-aryl ether linkage was well preserved at low severities, and the unsaturation in the side chain of hydrotropic lignin was high. H units and G units were preferentially degraded and subsequently condensed at high severity. High severity also resulted in the cleavage of part β-aryl ether linkage. ³¹P-NMR showed the decrease in aliphatic hydroxyl groups and the increasing carboxyl group content at high severity. The maximum weight loss temperature of the hydrotropic lignin was in the range of 330–350 °C, higher than the alkaline lignin, and the glass conversion temperature (T_g) of the hydrotropic lignin was in the range of 107–125 °C, lower than that of the alkaline lignin. The hydrotropic lignin has high β-aryl ether linkage content, high activity, nanoscale particle size, and low T_g, which is beneficial for its further valorization.     

The Use of Laser Induced Breakdown Spectroscopy (LIBS) to Study Catalyst Deactivation of V2O5/γ‐Al2O3 as Compared to Inductively Coupled Plasma Optical Emission Spectrometry

Laser Induced Breakdown Spectroscopy (LIBS) method is introduced as a novel approach in this work to study catalyst deactivation of V₂O₅/γ‐‐Al₂O₃ for gas‐phase dehydration of glycerol and producing acrolein. The LIBS results of V₂O₅/γ‐Al₂O₃ samples are compared with those data that are obtained by Inductively Coupled Plasma Optical Emission Spectrometry (ICP‐OES). Experimental data of LIBS data specify that line intensities of vanadium are decreased by deactivation of V₂O₅/γ‐Al₂O₃ catalyst. A comparison between the results of LIBS test as well as ICP‐OES analysis shows that the amount of vanadium is decreased in the catalyst. Moreover, coke formation changes the surface of the catalyst. The results of deactivation of V₂O₅/γ‐Al₂O₃ are also compared with Pd/C catalyst deactivation.     

γ-Valerolactone (GVL) as a green and efficient dipolar aprotic reaction medium

The great challenge for modern research is to define the most efficient tools to make more sustainable the industrial production and manufacturing. Among the different aspects that require attention the replacement of toxic and/or non-renewable solvents it is certainly playing a crucial role. Dealing with widely used dipolar aprotic solvents, among the different alternatives proposed in the literature γ-valerolactone (GVL) plays a pivotal role covering different application area. In this contribution, the benefits derived from the use of GVL as a circular, safe, biomass-derived reaction medium are highlighted covering most recent publications (2021). The presentation has been divided into three major sections: (i) biomass valorization, (ii) materials synthesis, manufacturing and recycle and (iii) new synthetic methodologies.     

Au促进Pt/WO3催化甘油氢解制1,3-丙二醇

近年来, 以生物质为基础的生物柴油得到了迅速发展, 导致了粗甘油过剩. 通过甘油选择性氢解制1,3-丙二醇, 进而被用于合成高价值的聚对苯二甲酸丙二醇酯被认为是最具工业应用潜力的反应之一, 对于提高生物柴油的利用效率有着极其重要的意义. 但由于反应空间位阻和热力学上的限制给甘油氢解制1,3-丙二醇带来了很大的挑战, 因此需要设计高活性的金属-酸双功能催化剂以降低甘油第二个C-O键断裂的活化能和减少其他副反应的发生. 目前Pt-W和Ir-Re双功能催化剂可高选择性制得1,3-丙二醇, 但仍需较严苛的反应条件实现对氢气的活化和解离. 本课题组曾将准单原子/单原子Pt高度分散于具有大量氧空位和酸位点的WOx载体上, 十分有利于甘油选择性氢解制1,3-丙二醇反应; 在Au-Pt/WOx催化剂中添加Au可促进B酸产生, 进而提高了甘油转化率和1,3-丙二醇的选择性.为了进一步研究Au对Pt/WOx催化剂结构和催化性能的影响, 本文利用CTAB辅助吸附法制备了Au/WO3, 再浸渍Pt制得Pt/Au/WO3双金属催化剂. 在甘油选择性氢解制1,3-丙二醇反应中, 所制催化剂表现出比Au-Pt/WOx更好的催化活性, 1,3-丙二醇时空收率为0.078 g1,3-PDO/(gcat·h), 是后者的1.95倍. 值得一提的是, Au-Pt/WOx催化剂在低压时活性较高, 而Pt/Au/WO3催化剂活性则在压力的升高而提高; 另外反应温度的升高导致副产物正丙醇的选择性上升, 1,3-丙二醇的选择性降低. 因此, 适宜的反应条件为155℃和5 MPa. 与Pt/WO3和Pt/WOx相比, Pt/Au/WO3表现出了更优异的催化性能, 其1,3-丙二醇的时空收率是Pt/WO3的2.36倍和Pt/WOx的4倍.为了探究Au的掺入对Pt/WOx催化剂性能的影响, 通过XRD, TEM, H2-TPR和XPS等技术对催化剂进行了深入表征. 结果表明, 与Pt/WO3相比, Pt/Au/WO3-600催化剂的XRD衍射峰向小角度偏移, 其原因是Au3+离子半径(0.85 ?)比W6+的(0.60 ?)大, Au3+以取代晶格W6+形式进入WO3晶格中; 对H2-TPR前300 ℃耗氢量的计算可知:Pt/WO3可被还原至Pt/WO2.96, 而Pt/Au/WO3可被还原至Pt/Au/WO2.91. 因此与Pt/WO3相比, Pt/Au/WO3表面氧空位更加丰富. TEM和XPS表征可知, 添加0.1 wt%Au后, 促进了更低价态的Pt均匀分散在WO3载体上, 其平均粒径为2.36 nm.综上所述, Au的掺杂改变了Pt/Au/WO3双金属催化剂的结构, 不仅降低了Pt和W的还原温度, 削弱了Pt和W之间的相互作用, 也促进了更低价态的Pt均匀分散于WO3载体上, 使得Pt/Au/WO3双金属催化剂在甘油氢解制1,3-丙二醇反应中具有更为优异的活性和产物选择性. 该催化剂有望被广泛运用于其他生物质平台化合物加氢脱氧的反应中.