Stability and Thermal Property Optimization of Propylene Glycol-Based MWCNT Nanofluids

Propylene glycol-based MWCNT(multi-walled carbon nanotubes)nanofluids were prepared in the framework of a two-step method and by using a suitable PVP(polyvinyl pyrrolidone)dispersant.The BBD(Box-Behnken design)model was exploited to analyze 17 sets of experiments and examine the sensitivity of the absorbance to three parameters,namely the concentration of MWCNT,the SN ratio(mass ratio of carbon nanotubes to sur-factants)and the sonication time.The results have revealed that,while the SN ratio and concentration of MWCNT have a strong effect on the absorbance,the influence of the sonication time is less important.The sta-tistical method of analysis of variance(ANOVA)was further used to determine the F-and p-values of the model.Five experiments were run to validate this approach.Since sample 2 was found to display the greatest absorbance,it was selected for stability monitoring as well as thermal conductivity and viscosity measurements.This sample has been found to be stable;the viscosity decreased with increasing temperature;the addition of MWCNT nano-particles was more effective in improving the thermal conductivity of propylene glycol than other methods in the literature.Moreover,the MWCNT nanofluid based on propylene glycol exhibited higher thermal conductivity at low temperatures.

Manipulating Zn^(2+)solvation environment in poly(propylene glycol)-based aqueous Li^(+)/Zn^(2+)electrolytes for high-voltage hybrid ion batteries

Compared with aqueous single-ion batteries,rechargeable aqueous hybrid ion batteries,especially Li^(+)/Zn^(2+)hybrid ion batteries,are receiving extensive interest owing to their low cost,high operating voltage,and energy density.However,their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites.Herein,detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol)(PPG)-based hybrid ion electrolyte[(1 m Zn(TFSI)2+10 m LiTFSI)in PPG/H2O].The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen-bond in water but also tailor the solvation sheath of Zn2+as revealed by synchrotron X-rays.The participated solvation of PPG with Zn^(2+)can weaken Zn-H_(2)O interactions and redistribute Zn^(2+)flux on the surface of the Zn anode,thus inducing favorably even deposition of Zn.In addition,the decomposition of TFSI-contributes a ZnF_(2)-enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites.The PPG-based electrolyte enables 2.1 V LiMnO_(2)//Zn batteries to deliver high specific capacities(121.7 mAh g^(-1)for a coin cell and 90 mAh g^(-1)for a pouch cell),and maintain 80%of the capacity over 700 cycles at 0.5 C,suggesting a promising pathway for highly reversible aqueous hybrid ion batteries.

Kinetics of Hydrogenolysis of Glycerol to Propylene Glycol over Cu-ZnO-Al2O3 Catalysts

A series of Cu-ZnO-Al2O3 catalysts with various metal compositions of Cu/Zn/Al were prepared by the co-precipitation method,and screened for glycerol hydrogenolysis to propylene glycol.The catalyst with a Cu/Zn/Al molar ratio of 1:1:0.5 exhibited the best performance for glycerol hydrogenolysis,and thus selected for kinetic investigation.Under elimination of external and internal diffusion limitation,kinetic experiments were performed in an isothermal fixed-bed reactor at a hydrogen pressure range of 3.0-5.0 MPa and a temperature range of 493-513 K. Based on a dehydration-hydrogenation two-step hydrogenolysis mechanism,a two-site Langmuir-Hinshelwood kinetic model taking into account competitive adsorption of glycerol,acetol and propylene glycol was proposed and successfully fitted to the experimental data.The average relative errors between observed and predicted outlet concentrations of glycerol and propylene glycol were 6.3%and 7.6%,respectively.The kinetic and adsorption parameters were estimated by using the fourth-order Runge-Kutta method together with the Rosenbrock algorithm.The activation energies for dehydration and hydrogenation reactions were 86.56 and 57.80 kJ·mol-1,respectively.

Preparation and shaping of solid acid SO_4^(2-)/TiO_2 and its application for esterification of propylene glycol monomethyl ether and acetic acid

The solid acid SO_4^(2-)/TiO_2 was prepared by immersion method and applied for synthesis of propylene glycol methyl ether acetate(PMA) through esterification reaction of propylene glycol monomethyl ether(PM)and acetic acid(HAc). The optimal catalyst preparation condition was determined by orthogonal analysis of parameters in a five-factor and four-level test. The obtained solid acid catalysts were characterized in detail by means of X-ray powder diffraction, thermogravimetry, pyridine adsorbed IR analysis, scanning electron microscopy, and BET surface area method. Synthesis of PMA was studied in this paper through experimental investigation of reaction conditions such as temperature, molar ratio of reactants, catalyst dosage and agitation speed. Based on its possible reaction mechanism, a pseudo-homogeneous kinetic model was established and its activation energies E_a^+ and E_a^-,65.68 × 10~3J·mol^(-1) and 57.78 × 10~3J·mol^(-1), were estimated. To prepare shaped solid acid catalyst SO_4^(2-)/TiO_2, the shaping method of impregnation–shaping–impregnation was applied. The optimal molding formulation of solid acid catalyst, obtained from the orthogonal test, was found to be binder 7 wt%, reinforcing agent 20 wt%, pore forming material 2.5 wt%, and lubricant 4 wt%.The results of performance test of catalyst demonstrated that the shaped solid acid catalyst exhibited high activity and stability.

Synthesis of 2-methylpyrazine from cyclocondensation of ethylene diamine and propylene glycol over promoted copper catalyst

The 2-methylpyrazine was synthesized by catalytic reaction of ethylene diamine and propylene glycol at 380 ℃. The alumina supported copper catalysts with promoter were prepared by impregnation method, characterized by ICP-AES, BET and TPR. The results demonstrated that the dehydrogenation was improved by addition of chromium promoter. The selectivity of 2-methylpyrazine reached 84.75%, while the conversions of reactants were also enhanced.

Zn–Ca–Al mixed oxide as efficient catalyst for synthesis of propylene carbonate from urea and 1,2-propylene glycol

A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.

IMPROVE OPTICAL CLEARING OF SKIN IN VITRO WITH PROPYLENE GLYCOL AS A PENETRATION ENHANCER

In order to enhance the optical clearing effect of topically applied optical clearing agents(OCAs),we evaluated the effect of propylene glycol(PG)as a chemical penetration enhancer(PE)on optical clearing of skin in vitro by observation and measurement of optical-transmittance and diffuse-reflectance spectra.Three OCAs,i.e.,glycerol,D-sorbitol and PEG400,and two other penetration enhancers,Azone and Thiazone,were used in this study.The results indicated that the decrease of reduced scattering coefficient caused by OCA/PG was larger than that by pure OCA,and the change by OCA/water was the least after the same treatment time.There were significant differences for the reduced scattering coefficient at 630 nm after 120 min application of agents between OCA and OCA/PG.The efficacy of optical clearing caused by OCA/PG depended on the OCA itself.When PEG400 was mixed with three different PEs,we found the optical clearing were different.The penetration enhancing ability of PG was much better compared to Azone,and suboptimal to Thiazone.Also,this study provides evidence for the use of PG as a PE in order to improve skin optical clearing.

Design and optimization of an integrated process for the purification of propylene oxide and the separation of propylene glycol by-product

It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed as extractant and 1,2-propylene glycol(MPG)that is formed from the PO hydrolysis reaction is recovered,is presented in this work.The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol(DPG)are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column.In addition,the ionic liquid(IL)extractant is screened through the conductorlike screening model for segment activity coefficient(COSMO-SAC)and the comparisons of separation efficiency between the IL and normal octane(nC_(8))extractant for the separation of PO and 2-methylpentane are made.With the non-random two-liquid(NRTL)thermodynamic model,the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio,theoretical stages,feeding stage etc.on separation efficiency are detailedly discussed.The results show that the mass purity and the mass yield of PO can be up to 99.99%and 99.0%,and the condenser duty,reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%,30.21%and 78.86%compared to ones with nC_(8).The total annual cost(TAC)calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC_(8) for the investigated process.The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.

Preparation, Characterization and Pharmacokinetics of Fluorescence Labeled Propylene Glycol Alginate Sodium Sulfate

A rapid and sensitive fluorescence labeling method was developed and validated for the microanalysis of a sulfated polysaccharide drug,namely propylene glycol alginate sodium sulfate(PSS), in rat plasma. Fluorescein isothiocyanate(FITC) was selected to label PSS, and 1, 6-diaminohexane was used to link PSS and FITC in order to prepare FITC-labeled PSS(F-PSS) through a reductive amination reaction. F-PSS was identified by UV-Vis, FT-IR and 1H-NMR spectrum. The cell stability and cytotoxicity of F-PSS were tested in Madin-Darby canine kidney(MDCK) cells. The results indicated that the labeling efficiency of F-PSS was 0.522% ± 0.0248% and the absolute bioavailability was 8.39%. F-PSS was stable in MDCK cells without obvious cytotoxicity. The method was sensitive and reliable; it showed a good linearity, precision, recovery and stability. The FITC labeling method can be applied to investigating the absorption and metabolism of PSS and other polysaccharides in biological samples.

Simulation and design of a heat-integrated double-effect reactive distillation process for propylene glycol methyl ether production

A double-effect reactive distillation(DERD)process was proposed for the production of propylene glycol methyl ether from propylene oxide and methanol to overcome the shortcoming of low selectivity and high-energy consumption in the tubular plug-flow reactor.A single-column reactive distillation(RD)process was conducted under optimized operating conditions based on sensitivity analysis as a reference.The results demonstrated that the proposed DERD process is able to achieve more than 95%selectivity of the desired product.After that,a design approach of the DERD process with an objective of the minimum operating cost was proposed to achieve further energy savings in the RD process.The proposed DERD configuration can provide a large energy-savings by totally utilization of the overhead vapor steam in the high-pressure RD column.A comparison of the single-column RD process revealed that the proposed DERD process can reduce the operating cost and the total annual cost of 25.3%and 30.7%,respectively,even though the total capital cost of DERD process is larger than that of the RD process.

Waste Management in Propylene Epoxidation Process with the Use of Supercritical Fluid Media

Experimental results on solubility of the styrene, phenol, methylphenylcarbinol, acetophenone, ethyl benzene, propylene glycol and molybdenum as a complex with Trilon B in supercritical CO2 obtained using a dynamic (flow) method are presented. The obtained data are described in the framework of Peng-Robinson equation. The results of the experients on the extraction of organic components from waste formed in the olefin epoxidation process at Nizhnekam-skneftekhim Inc., on the analysis of extract composition, and on the testing of the extract as an epoxidation catalyst are presented. The supercritical water oxidation (SCWO) process of epoxidation process waste was conducted in periodical and continuous mode. The analysis results of reaction product are given. Pilot experiments on dry sediment formation were conducted using Radio Frequency (RF) Inductively Coupled Plasma (ICP) of low pressure.

负载碳酸钙的水包油包固乳液稳定性及相互作用研究

碳酸钙由于分散稳定性差,很难在食品基质中传递。水包油包固(solid-in-oil-in-water,S/O/W)三相载体乳液作为食品营养素的载体,具有制备成本低、工艺简单等优点。为提高碳酸钙在液态食品中的分散稳定性,实现较高品质利用,该文以黄原胶(xanthan gum,XG)和海藻酸丙二醇酯(propylene glycol alginate,PGA)复凝聚为水相,精制猪油为油相,通过高速剪切分散构建负载碳酸钙的S/O/W钙-脂质乳液,考察PGA和XG复凝聚的界面活性和相互作用,研究不同配比PGA-XG复合物制备乳液的物理稳定性、Zeta电位、表观黏度、粒径分布及微观结构。结果表明,PGA与XG以氢键的方式产生相互作用,复凝聚后显著降低了XG在油水界面的表面张力;m(PGA)∶m(XG)=4∶6时,乳液Zeta电位为(-43.3±0.1)mV,平均粒径为(1.59±0.08)μm,有较好的物理稳定性和流变学特性,碳酸钙位于油相内部。该研究结果可丰富构建S/O/W传递系统理论,为开发新型营养素输送载体提供参考。

三嵌段共聚物临界胶束浓度与分子横截面积测定

采用双毛细管最大泡压法装置测定了25℃条件下不同浓度非离子表面活性剂聚乙二醇-聚丙二醇-聚乙二醇三嵌段共聚物(PEG-PPG-PEG;Pluronic L-64)对溶液表面张力的影响。采用Origin软件对数据进行处理分析,计算得到其临界胶束浓度(CMC)。基于吉布斯(Gibbs)与朗格缪尔(Langmuir)吸附等温式,对溶液表面张力与浓度关系进行一步非线性拟合,计算获得吸附分子的横截面积。该实验扩展了最大泡压法测定表面张力的应用,提高了学生分析处理实验数据的能力。

葵盘果胶与海藻酸钠丙二醇酯复配在搅拌型酸奶中的应用

将葵盘果胶与海藻酸钠丙二醇酯(PGA)进行复配并应用在酸奶中以弥补单独葵盘果胶在搅拌型酸奶中应用时的不足。本研究以单因素实验结果为基础,将葵盘果胶、PGA添加量作为变量因素,以酸奶的感官评价得分、表观黏度、脱水收缩敏感性、持水能力、凝胶强度为响应值,通过响应面法建立分析模型确定两者复配在酸奶中应用的最佳优化配方。结果表明,响应面优化的亲水性胶体添加量为:0.22g/100 g葵盘果胶,0.10 g/100g PGA。本实验为葵盘果胶及葵盘果胶与PGA复配胶在搅拌型酸奶工业的应用提供了理论依据。

新型保润剂丙二醇吡咯酯的制备及其对再造烟叶保润效果研究

为克服传统保润剂丙二醇在加热烟草制品中吸湿性过强的缺点,制备了一种新型保润剂丙二醇吡咯酯,并利用热重-微商热重-差示扫描量热法、热裂解气相色谱/质谱和低场核磁共振技术考查其热行为及其在再造烟叶中的保润效果。结果表明:丙二醇吡咯酯的热失重区间为149.9~400.0℃,在298.7℃时质量损失率达最大(77.39%);在200℃、300℃和350℃下的主要裂解产物为吡咯酸和丙二醇,其中丙二醇可以起到协调和降低烟气干燥感的作用;在低湿环境下添加丙二醇吡咯酯的再造烟叶丝保润能力高于空白组,但低于丙二醇组;丙二醇组、丙二醇吡咯酯组和空白组中再造烟叶丝内部结合水占比分别为75%、70%、68%,即丙二醇吡咯酯可以降低再造烟叶丝的强吸湿性,同时保持一定的保润能力。

Implementation of a New Solution for the Preservation of Anatomical Specimens Made of Non-Toxic Substances

The preservation of anatomical pieces in Veterinary Anatomy is essential since it is not possible to dissect all domestic species. Most techniques use reagents with high levels of toxicity such as formaldehyde. The objective of this work was to develop a new preservation technique that uses reagents with zero toxicity and that allows obtaining preserved pieces suitable for anatomical studies. The alcohol propylene glycol technique was developed, the method of which uses a fixation step with alcohol, sodium chloride, commercial vinegar and subsequently the impregnation of the preservation solution made from propylene glycol and commercial vinegar, which are non-toxic. As a result of this work, adequately preserved sheep hearts were obtained that preserved their morphology with slight changes in size and weight, which did not affect their external and internal anatomical structure. Its coloration was not substantially affected, remaining a little lighter. The pieces obtained showed flexibility which allowed dissections to be carried out. The time to develop the technique was 20 days. A comparative study was carried out with the phenolated glycerin technique that uses toxic reagents (formaldehyde and phenol) and the pieces obtained with the alcohol propylene glycol technique were of better quality, observing that the pieces with phenolated glycerin tend to darken and are more rigid. And the time to develop the technique is 24 days. In conclusion, a preservation technique for anatomical pieces was developed that allowed the preservation of the organs under study, which allow their use for anatomical studies, and which have been preserved without changes until the time of this publication (8 months) and there are pieces preserved with this technique for 2 years.

聚醚酯消泡剂在白水中的性能研究

本研究表征了以不同官能度的聚醚(脂肪醇聚醚、丙二醇聚醚、甘油聚醚,官能度分别为1、2、3)和脂肪酸为原料合成的聚醚酯结构,着重探讨了3种官能度聚醚酯的消泡性能。结果表明,硬脂酸为优选脂肪酸,起始剂为十八醇、环氧乙烷(EO)与环氧丙烷(PO)物质的量比为3∶7时,合成的脂肪醇聚醚酯消泡剂的消泡性能最佳;POEO或EOPOEO嵌段的丙二醇聚醚酯(EO在聚醚链段末端)具有良好的消泡效果;相对分子质量3 000的甘油聚醚合成的甘油聚醚酯消抑泡效果最佳。优选的十八醇聚醚酯在低温生活用纸白水中消抑泡效果好,丙二醇聚醚酯和甘油聚醚酯分别在高温箱纸板和文化用纸白水中消抑泡效果好。3种聚醚酯溶液浓度增至0.6 g/L时,表面张力均为27.0 mN/m。

气液萃取精馏分离乙二醇中的高碳数杂醇

二元醇混合物的分离是生物质基乙二醇工业应用的重要环节,但传统精馏技术的分离效率较低。通过引入气态萃取剂,使其与特定组分之间发生相互作用,选择性地促进这些组分的气化,从而提高精馏的分离效率。实验结果表明:一方面气态正丁醇与气膜内部及相界面处的丙二醇、丁二醇分子发生较强的相互作用,有效地促进了丙二醇、丁二醇从液相到气相的传质过程;另一方面,由于正丁醇与乙二醇的极性相差较大、相互作用较弱,其对乙二醇分子从液相到气相的迁移的促进作用较弱,故无助于乙二醇的气化。这种选择性促进作用使塔顶的丙二醇、丁二醇浓度得以提升,从而强化了精馏分离效果。在气态正丁醇的作用下,初始馏出物中丙二醇的质量分数从43%提高到50%,丁二醇的质量分数从14%提高到17%。与传统的萃取精馏技术相比,气液萃取精馏的萃取剂夹带量少,且所夹带的萃取剂易于去除,设备简单,能耗较低。本研究为特种精馏技术的发展提供了新思路。

共沸法回收废稀释剂中PGMEA和PGME的研究

丙二醇甲醚醋酸酯(PGMEA)和丙二醇甲醚(PGME)的混合物是电子行业使用的一种优良稀释、清洗溶剂,稀释、清洗后产生含有PGMEA、PGME和水等物质的废稀释剂,PGMEA和PGME与水都会形成共沸物,采用普通精馏法难以得到较高的回收率。以环己烷为共沸剂,利用环己烷与水产生的共沸物沸点更低的特性,通过共沸精馏法回收废稀释剂中的PGMEA和PGME。应用流程模拟分析剂/水比、回流比等操作参数对原料脱水及产品回收率的影响,结果表明:共沸塔剂/水比为10∶1、PGME成品塔回流比为8、PGMEA成品塔回流比为0.45时,回收的PGME产品质量分数为99.01%,PGMEA产品质量分数为99.04%。与普通精馏回收工艺相比,共沸法的PGME产品回收率从40.57%提升至81.15%,PGMEA产品回收率从99.68%提升至99.90%,精馏系统吨产品的能耗从6.30MJ/t增加至7.76MJ/t。