Supercritical Synthesis of Ethyl Esters via Transesterification from Waste Cooking Oil Using a Co-Solvent

Biofuels became more promising alternative to the fossil fuels because of the depletion of fossil resources, renewability, environmental benefits, and energy security. Ethanolysis of waste cooking oil with hexane as co-solvent was carried out for the production of fatty acid ethyl ester (FAEE). This process reduced the severity of process parameters with high purity biodiesel yield. Process variables such as co-solvent ratio, ethanol to oil molar ratio, reaction temperature and reaction time were optimized. The maximum biodiesel yield of 88% was obtained at ethanol/oil molar ratio of 40:1, co-solvent (hexane) to oil ratio of 0.2% (v/v), reaction temperature of 300°C in 20 min of reaction time. Fatty acid ethyl ester (biodiesel) samples produced from this process were measured and evaluated using GC-MS analytical instrument. Thermo gravimetric analysis (TGA) was also performed to examine the thermal stability of waste cooking oil, ethyl esters and fuel blends. Fuel properties of ethyl esters were determined and compared with the ASTM standards for biodiesel, regular diesel and ethyl esters from different feedstock.

Enhancement of Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquid with DMSO Co-solvent

Caffeic acid phenethyl ester(CAPE) is a natural and rare ingredient with several biological activities, but its industrial production using lipase-catalyzed esterification of caffeic acid(CA) and 2-phenylethanol(PE) in ionic liquids(ILs) is hindered by low substrate concentrations and long reaction time. To set up a high-efficiency bioprocess for production of CAPE, a novel dimethyl sulfoxide(DMSO)–IL co-solvent system was established in this study.The 2%(by volume) DMSO–[Bmim][Tf2N] system was found to be the best medium with higher substrate solubility and conversion of CA. Under the optimum conditions, the substrate concentration of CA was raised 8-fold,the reaction time was reduced by half, and the conversion reached 96.23%. The kinetics follows a ping-pong bi-bi mechanism with inhibition by PE, with kinetic parameters as follows: Vmax= 0.89 mmol · min-1· g-1, Km,CA=42.9 mmol · L-1, Km,PE= 165.7 mmol · L-1, and Ki,PE= 146.2 mmol · L-1. The results suggest that the DMSO cosolvent effect has great potential to enhance the enzymatic synthesis efficiency of CAPE in ILs.

Optimization of Biodiesel Production from Waste Vegetable Oil Assisted by Co-Solvent and Microwave Using a Two-Step Process

The two-step catalyzing process for biodiesel production from waste vegetable oil was assisted by both co-solvent and microwave irradiation. Central composite design (CCD) was employed to optimize the reaction conditions. Optimal reaction conditions of the first step were alcohol to oil molar ratio of 9:1, catalyst (H2SO4) amount 1 wt%, reaction temperature 333 K, and reaction time 7.5 minutes;while for the second step, optimal reaction conditions were alcohol to oil molar ratio 12:1, catalyst (NaOH) amount 1 wt%, reaction temperature 333 K, and reaction time 2.0 minutes. The total reaction time was 9.5 min and the conversion rate of fatty acid methyl esters (FAMEs) achieved was 97.4%. The total reaction time was shorter than previous studies. Therefore, the co-solvent and microwave assisted two-step catalyzing process has a potential application in producing biodiesel from waste vegetable oil.

Effect of Co-solvent and Pressure on the Thermal Decomposition of 2,2′Azobis-(isobutyronitrile) in Supercritical CO_2

The thermal decomposition of 2, 2'-azobis (isobutyronitrile) (AIBN) in supercritical CO2 with cosolvent methanol or cyclohexane has been studied by using UV/Vis spectroscopic method at 335.15 K and at 12.0 MPa and 14.0 MPa. Both of the cosolvents can accelerate the decomposition rate, and the effect of methanol is more significant than that of the cyclohexane.

Influence of Co-Solvent on the Extraction Behaviour of Uranium and Thorium Nitrates with Organophosphorous Compounds

Supercritical Fluid Extraction (SFE) is emerging as a powerful technique in the extraction of metal ions. In the present study, the extraction of nitrates of uranium and thorium was carried out using supercritical carbon dioxide (Sc-CO2) modified with various organophosphorous compounds such as dialkylalkyl phosphonates, trialkyl phosphates and trialkyl phosphine oxides in the presence of co-solvents such as methanol, dichlormethane and n-hexane. The influence of ligand and co-solvent on the extraction of the metal nitrates was studied in detail. These studies have established that co-solvent plays an important role in the extraction as well as fractionation of uranium and thorium nitrates. Polar co-solvent, methanol provided faster extraction without fractionation whereas the non-polar solvent, e.g. n-hexane provided some fractionation of metal nitrates though the extraction kinetics was slower.

Dispersion of ZnO Nanocrytals in Co-solvent and Its Application in Photovoltaic Material

To overcome the aggregation of nanocrystals in a blend of inorganic material with conjugated polymers to prepare photovoltaic material, we used a co-solvent blend of CHCl3 with MeOH at a certain volume fraction to disperse inorganic nanocrystals. The results show that when the volume fraction of MeOH is 50%, ZnO nanocrystals with an average diameter of 30 nm disperse well in the co-solvent solution. Its application in photovoltaic material was investigated in this work, and the photoluminescence（PL） spectra show that when ZnO was 50%（volume fraction） in solution and 25%（volume fraction） in film, the fluorescence quenching reached the maximum values 83.34% and 64.4%, respectively, indicating that electron could transfer from conjugated polymer to electron-acceptor ZnO effectively.

Effects of Water-Soluble Co-Solvent on Properties of W/O Pickering Emulsions

Effects of water-soluble co-solvents （WSCs）on the properties of water/oil Picketing emulsions were investigated. Picketing emulsions were prepared in the system of 1,2,4-trimethylbenzene （TMB）/hydrophobic sil- ica/water with varied concentrations of WSCs （ethanol, acetic acid and glycerin）. Mean droplet diameter distribu- tions of the obtained emulsions were studied to investigate the effects of WSCs types and concentrations. The results demonstrated that mean droplet diameter distributions decreased at first and then increased with the increase of WSC concentration. Moreover, the effect of WSC concentration on the phase inversion locus was further investi- gated. At the same time, infrared radiation （IR）spectrometer was used to investigate the mechanism. The results showed that the WSC attaching on hydrophobic silica changed the wettability of the particles, which facilitated the formation and phase inversion of the emulsion. The hydrogen bonds between the co-solvent groups attaching on the solid particles made a great effect on the droplet size of the emulsion and strengthened the interaction among emulsifiers. Overall, proper WSC was in favor of the stability of Picketing emulsion.

牛血清白蛋白乳酸-羟乙酸共聚物微球的制备

目的 以牛血清白蛋白为模型蛋白,以乳酸羟乙酸共聚物(PLGA)为包裹材料,探索粒径小于10 μm的微球的制备方法并优化工艺。方法 采用复乳溶剂挥发法制备蛋白质微球,以BCA法及微量BCA法测定微球的蛋白含量及蛋白从微球的释放。考察BSA浓度、内外相体积比、PLGA浓度、超声功率、匀浆转速、PVA浓度、PVA体积、PLGA分子量等因素对微球包封率、粒径、载药量及突释量的影响。结果 通过控制不同的因素,可以得到较高的载药量及包封率、粒径在5 μm左右的微球。结论 采用复乳溶剂挥发法通过控制不同的因素,可得到粒径5 μm左右不同载药量及突释量的具有较高包封率的微球。

乙醇柴油的物化性质研究

分析了乙醇柴油的相溶性、十六烷值、密度、运动粘度、凝点和冷滤点、腐蚀性、闪点和馏程等性质。考察了乙醇含量及助溶剂对乙醇柴油物化性质的影响。结果表明,乙醇体积分数升高相溶性变差,在50%左右相溶性最差;加入助溶剂能明显改善乙醇和柴油的相溶性。十六烷值随乙醇体积分数升高而减小,乙醇体积分数为10%时十六烷值减小约5个单位;加入乙醇后,柴油的密度、运动粘度都有不同程度的减小;腐蚀性和凝点变化不大。乙醇柴油的闪点接近乙醇的闪点,初馏点接近乙醇的沸点。最后对乙醇柴油产品标准的制定提出了建议。

顶空气相色谱法测定药品中残留溶剂的影响因素考察

目的:考察顶空气相色谱法测定药品中残留溶剂时常见的共出峰干扰和热降解干扰,提出减少这些干扰的对策。方法:采用不同极性的毛细管色谱柱测定吡柔比星、头孢氨苄中的残留溶剂,考察共出峰对残留溶剂测定的干扰;在不同的顶空条件下测定头孢西丁钠等药品中的甲醇残留量,考察分子结构中有甲氧基的药品在顶空条件下的热稳定性。结果:用不同极性的色谱柱可以排除吡柔比星、头孢氨苄中的共出峰干扰;含甲氧基的药品在较高顶空温度下降解产生甲醇。结论:用顶空气相色谱法测定药品中残留溶剂时应排除共出峰和热降解干扰。

An effective'salt in dimethyl sulfoxide/water'electrolyte enables high-voltage supercapacitor operated at-50℃

Compared with organic electrolytes,aqueous electrolytes exhibit significantly higher ionic conductivity and possess inherent safety features,showcasing unique advantages in supercapacitors.However,challenges remain for low-salt aqueous electrolytes operating at high voltage and low temperature.Herein,we report a low-salt(0.87 m,m means mol kg^(-1))'salt in dimethyl sulfoxide/water'hybrid electrolyte with non-flammability via hybridizing aqueous electrolyte with an organic co-solvent of dimethyl sulfoxide(hydrogen bond acceptor).As a result,the 0.87 m hybrid electrolyte exhibits enhanced electrochemical stability,a freezing temperature below-50℃,and an outstanding ionic conductivity of 0.52mS cm~(-1)at-50℃.Dimethyl sulfoxide can anchor water molecules through intermolecular hydrogen bond interaction,effectively reinforcing the stability of water in the hybrid electrolyte.Furthermore,the interaction between dimethyl sulfoxide and water molecules diminishes the involvement of water in the generation of ordered ice crystals,finally facilitating the low-temperature performance of the hybrid electrolyte.When paired with the 0.87 m'salt in dimethyl sulfoxide/water'hybrid electrolyte,the symmetric supercapacitor presents a 2.0 V high operating voltage at 25℃,and can operate stably at-50℃.Importantly,the suppressed electrochemical reaction of water at-50℃further leads to the symmetric supercapacitor operated at a higher voltage of 2.6 V.This modification strategy opens an effective avenue to develop low-salt electrolytes for high-voltage and low-temperature aqueous supercapacitors.

水相循环对乙醇-水体系液化蜈蚣草产油特性和砷富集影响

砷富集植物的生态友好处置是实现植物修复产业化发展的关键环节,对土壤重金属污染治理高质量发展起到了制约作用。该研究以蜈蚣草为原料,采用乙醇-水作为反应共溶剂体系,考察了乙醇占比和水相循环次数对蜈蚣草水热产油及重金属砷分布的影响。研究结果显示:在乙醇浓度60%、水相循环3次的条件下,蜈蚣草液化生物油产率最高可达51.08%,其热值为29.15 MJ/kg。生物油主要由酯(>80%)、酚、醇、酮、烃等组成。随水相循环次数的增加,生物油中的酯类和酚类物质增加,高沸点化合物会减少,生物油产率和能量回收率分别提高了58%和32.23%;经过水相循环液化后,超过80%的重金属砷主要分布在水相,且砷的浓度增加至215.05 mg/kg,该结果可为砷富集植物无害化后处置提供参考。因此,水相循环利用是砷富集植物液化处置制取高产率生物油与砷富集的有效途径,为富集植物生态友好处置提供了新的思路。

柔性压电复合材料的研究进展

柔性压电复合材料常被应用于医学和航空航天等多个领域,具有广阔的工程应用前景和巨大的商业价值。因此,综述了柔性压电复合材料,介绍了以聚二甲基硅氧烷(PDMS)为代表的柔性基体和纳米填料。随后分析了制备工艺以及在制备中出现的团聚问题。同时,总结了物理与化学分散法以及双亲助溶剂促进分散的机理。最后归纳了机器学习(ML)、分子模拟和宏观试验3种研究方法。

Fabricating low-temperature-tolerant and durable Zn-ion capacitors via modulation of co-solvent molecular interaction and cation solvation

Aqueous Zn-based energy-storage devices have aroused much interest in recent years.However,uncontrollable dendrite growth in the Zn anode significantly limits their cycle life.Moreover,the poor low-temperature performance arising from the freezing of aqueous electrolytes at sub-zero temperatures restricts their practical applications in cold regions.Here,we fabricated low-temperature-tolerant and durable Zn-ion hybrid supercapacitors(ZHSCs)via modulating a co-solvent water/ethylene glycol electrolyte.The interaction of intermolecular hydrogen bonds between water and ethylene glycol as well as cation solvation was systematically investigated by tuning the co-solvent composition.The results illustrate that the ZnSO_(4)/water/ethylene glycol(65%)electrolyte possesses high ionic conductivity at low temperatures and effectively prevents the dendrite formation of the Zn anode.The as-fabricated ZHSCs exhibit long-term cyclability and are capable of working at sub-zero temperatures as low as -40℃.The present ZHSCs are anti-freezing and cost-effective,which may find new applications in the fields of next-generation electrochemical energy storage devices.

锂离子电池低温电解液的挑战及研究进展

近年来,锂离子电池(LIB)已广泛应用于便携式电子设备、电动汽车、储能领域,是目前最有前景的新能源应用技术之一。然而低温条件下,LIB仍面临循环寿命和能量/功率密度衰减过大等诸多挑战,严重限制了其在极端工况下的实际应用。其主要原因包括:Li+在电极材料中的扩散及其界面处的电荷传递和去溶剂化过程较为缓慢;电解液粘度增大,对材料和隔膜的润湿性变差;石墨负极嵌锂时容易形成锂枝晶等。基于多年来低温锂离子电池的开发经验和相关文献报道,从电解液的角度综述了提高低温锂离子电池的策略,重点介绍了低粘度、宽液程的共溶剂,高电导率、低去溶剂化能的新型锂盐以及形成薄且致密固体电解质中间相(solid electrolyte interphase,SEI)的成膜添加剂对低温性能的影响及其挑战,并对未来低温电解液的发展方向进行了展望。

7-羟乙基白杨素聚乳酸-羟基乙酸共聚物纳米粒的制备及体外释放评价

目的:制备和评价7-羟乙基白杨素(7-HEC)聚乳酸-羟基乙酸共聚物(PLGA)纳米粒。方法:采用乳化溶剂挥发法制备7-HEC/PLGA纳米粒,以粒径、多分散系数(PDI)、包封率、载药量及Zeta电位为评价指标,通过单因素考察结合Box-Behnken响应面法优化处方。采用甘露醇作为冻干保护剂制备冻干粉,对最优处方制备的7-HEC/PLGA纳米粒进行表征及体外释放研究。结果:经Box-Behnken响应面法优化后的最优处方为:药载比2.12∶20,油水体积比1∶14.7,乳化剂为2.72%大豆磷脂。最优处方条件制备的7-HEC/PLGA纳米粒的平均粒径为(240.28±0.96)nm、PDI为0.25±0.69、包封率为(75.74±0.80)%、载药量为(6.98±0.83)%、电位为(-18.17±0.17)mV。体外释放48 h内累积释放度达到50%以上。结论:优化所得处方工艺稳定、操作简便。所得7-HEC/PLGA纳米粒粒度均匀,包封率较高。相对于7-HEC原料药,7-HEC/PLGA纳米粒的溶出度显著提高。

聚丁二酸-共-对苯二甲酸丁二醇酯/氧化镁复合薄膜的制备及性能

以聚丁二酸-共-对苯二甲酸丁二醇酯(PBST)为基体,纳米氧化镁(MgO NPs)为抗菌剂,通过溶剂挥发法制备了PBST/MgO纳米复合薄膜,并探讨了复合薄膜在食品包装中的应用。研究了MgO NPs对纳米复合薄膜的机械性能、水蒸汽透过率(WVP)、氧气透过率(OTR)和紫外阻隔性能的影响。结果表明:MgO NPs的加入改善了PBST基体的力学性能和阻隔性能。与PBST薄膜相比,复合膜的拉伸强度和断裂伸长率分别提高了43.7%和32.2%,水蒸汽透过率和氧气透过率分别降低了28.1%和23.6%,并具有良好的紫外阻隔性能。当MgO NPs质量含量为5%时,复合膜的性能最佳。

细乳液法合成无溶剂水性聚氨酯

以聚丙二醇(PPG-1000)、4,4-二环己基甲烷二异氰酸酯(HMDI)、二羟甲基丙酸(DMPA)、三乙胺(TEA)、聚四氢呋喃醚二醇(PTMG650)、1,4-丁二醇(BDO)以及液体石蜡(CS)为主要原料,PTMG650为反应型助稳定剂并改变其用量,采用细乳液法合成了一系列无溶剂水性聚氨酯(WPU),并研究了反应型助稳定剂的比例对水性聚氨酯性能的影响。结果表明,随着PTMG650比例的增加,聚氨酯胶膜分子链的柔顺性越来越好;胶膜的拉伸强度从26.7 MPa降低到7.2 MPa,杨氏模量从144.4 MPa降低到19.8 MPa。此外,所有胶膜具有良好的耐热性和耐水性。

星点设计-效应面法优化万古霉素-聚富马酸丙二醇酯/聚乳酸-羟基乙酸共聚物微球的制备工艺

背景:万古霉素为骨髓炎治疗首选抗生素之一,局部给药不仅能发挥其抗菌作用,而且还能大幅减少全身不良反应。目的:优选万古霉素-聚富马酸丙二醇酯/聚乳酸-羟基乙酸共聚物微球的制备工艺,并考察其体外释放行为及细胞毒性。方法:采用复乳溶剂挥发法(W1/O/W2)制备万古霉素-聚富马酸丙二醇酯/聚乳酸-羟基乙酸共聚物微球,以微球的包封率和载药量为评价指标,应用星点设计-效应面法考察聚富马酸丙二醇酯和聚乳酸-羟基乙酸共聚物质量比、聚富马酸丙二醇酯和聚乳酸-羟基乙酸共聚物与万古霉素的质量比、二氯甲烷浓度对制备工艺的影响,对结果进行多元线性回归和二项式拟合,效应面法优选最佳工艺条件,测量微球的粒径、ζ电位、体外释放行为及细胞毒性。结果与结论:(1)成功制备了微球,优选聚合物微球的最佳制备工艺为:聚富马酸丙二醇酯与聚乳酸-羟基乙酸共聚物的质量比=2.41、聚富马酸丙二醇酯/聚乳酸-羟基乙酸共聚物与药物质量比=3.56、CH2Cl2浓度为129.73 g/L,实测平均包封率为83.38%,与预测值相比偏差为0.63%;实测平均载药量为18.19%,与预测值相比偏差为0.55%;(2)最佳工艺制得微球的平均粒径为103.902μm,ζ电位为-21.5 mV;微球体外3 d后累计释药量为(22.90±0.55)%,28 d后累计释放量达(43.57±1.02)%,28 d后微球释药明显增快,42 d时累计释放量为(97.89±1.39)%;微球细胞毒性分级为1级;(3)星点设计-效应面法优化微球制备工艺预测性良好,所优化的制备工艺重现性好、简单易行,所制备的微球具有较好的体外缓释特性和生物相容性。

共溶剂对聚乳酸相对分子质量及热性能的影响

以超临界二氧化碳(SC-CO2)为载体,分别以丙酮、无水乙醚、六氟异丙醇为共溶剂,合成聚乳酸(PLLA),并采用FT-IR、GPC和DSC等对所获得的聚合物进行了相对分子质量测定和结构性能表征,探讨了3种共溶剂对用SC-CO2为溶剂合成的PLLA相对分子质量及热性能的影响。结果表明,共溶剂对PLLA的相对分子质量、相对分子质量分布指数以及热性能影响较大;以丙酮为共溶剂时,可以获得最高相对分子质量为47 690且热性能较好的PLLA。