Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

yb3＋/Dy3＋ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3＋, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3＋ and Dy3＋ is discussed.

In-situ Characterization of Non-aqueous Nano-dispersion Systems by Freeze-etching TEM and Comparative Study with Laser Scattering Method

In-situ characterization of non-aqueous nano-dispersion systems（NANDS） by freeze-etching transmission electron microscope（FETEM） was reported.To improve just-for-once successive rate of specimen preparation and get good characterization results,an improving specimen preparation method of freezing etching was developed.Size,distribution and morphology of NANDS were directly visualized.Some information of particle dispersion feature and particle density can also be obtained.Reproductivity of the FETEM characterization is excellent.Comparing with laser scattering method,which is liable to give positive error especially for small size particle anchoring disperser,FETEM characterization can give more accurate measurement of particle size.Moreover,FETEM can give dispersion feature of nanoparticle in non-aqueous medium.

Stoichiometry and Stability Constant Values for Copper (II) Chelates with Ethylene Diamine in Deep Eutectic Solvents (DES) (Ethaline) Solutions

In this study we used the deep eutectic solvents (ionic liquids) to investigate the reaction between copper (II) with ethylene diamine (en). Two of the existing methods for analyzing spectrophotometric measurements have been applied for establishing, the stoichiometry and whenever possible, the stability constants of the chelates formed. The method of continuous variations was necessary to determine first whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the wavelength and for meaningful conclusions the wavelengths were carefully selected. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also studied. The stability constants, K1 and K2 for the copper (II) chelates were calculated, though reliable, and are comparable to literature values.

Preparation of PLA and PLGA nanoparticles by binary organic solvent diffusion method

The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.

Synthesis and Characterization of Alumina-Zirconia Powders Obtained by Sol-Gel Method: Effect of Solvent and Water Addition Rate

The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.

Thermodynamic solvation of a series of homologous α-amino acids in non-aqueous mixture of ethylene-glycol and N,N-dimethyl formamide

Standard free energies (ΔG0t(i) ) and entropies (ΔS0t(i)) of transfer of some homologous α-amino acids viz. glycine (gly), dl-alanine (ala), dl-α-amino butyric acid (aba) and dl-nor-valine (nor-val) from protic ethylene glycol (EG) to dipolar aprotic N,N-dimethyl formamide (DMF) have been evaluated from solubility measure-ments at five equidistant temperatures i.e from 15 to 350C. The observed ΔG0t(i) and TΔS0t(i) Vs composition profiles are complicated because of the various interaction effects. The chemical effects of the transfer Gibbs energies (ΔG0t.ch(i)) and entropies of transfer (ΔS0t.ch(i)) have been obtained after elimination of cavity effect, estimated by the scaled particle theory and dipole-dipole interaction effects, estimated by the use of Keesom-orientation expression. The chemical contributions of transfer energetics of homologous α-amino acids are guided by the composite effects of increased dispersion interaction, basicity and decreased acidity, hydrogen bonding effects and solvophobic solvation of ethylene glycol and N, N-dimethyl formamide mixed solvent as compared to that of reference solvent (ethylene glycol).

STUDY ON SLOW-RELEASE CHARACTERISTICS OF MICROCAPSULES WITH EMULSION NON-SOLVENT ADDITION METHOD

An O / W emulsion non-solvent addition method was used to prepare ethyleellulose (EC) microcapsules of water soluble pharmaceutical (theophylline). The solvent and non-solvent reagents used in this work were toluene and cyclohexane. The effects of polymer concentration, core wall ratio and particle size on the kinetics as well as the dissolution rate of the drug were investigated. The results show that the dissolution rate increases with the increasing of polymer concentration and core wall ratio. The release of microcapsules prepared with different procedures can be selectively profiled with first order and Higuchi matrix kinetic models.

超声有机溶剂法提取茶树花精油工艺优化及其成分分析

以茶树花为原料,采用超声有溶剂法提取茶树花精油。以茶树花精油得率为指标,在单因素试验的基础上通过响应面法优化提取工艺,并与索氏抽提法对比分析茶树花精油得率及其挥发性成分。结果表明:超声有机溶剂法提取茶树花精油的最佳工艺为超声功率240W、超声时间50min、石油醚添加量160mL、浸泡时间6h,在此条件下,茶树花精油得率为3.34%,而索氏抽提法的茶树花精油得率为1.59%。成分分析显示,在超声有溶剂法提取的茶树花精油中共检出23种挥发性成分,而在索氏抽提法提取的茶树花精油中只检出18种挥发性成分。

金银花总黄酮低共熔溶剂提取工艺优化

目的优化金银花总黄酮低共熔溶剂提取工艺。方法在单因素试验基础上,以1,3-丁二醇与氯化胆碱比例、液料比、超声时间为影响因素,总黄酮得率为评价指标,响应面法和BP神经网络优化提取工艺。结果BP神经网络优化总黄酮得率高于响应面法优化。最优条件为1,3-丁二醇与氯化胆碱比例2.7∶1,液料比27∶1,超声时间29 min,总黄酮得率为7.85%。结论该方法稳定可靠,可用于低共熔溶剂提取金银花总黄酮。

溶剂法提纯硫磺的工艺研究

为了解决天然气净化过程中副产物硫磺提纯难度大、提纯后硫磺纯度低的问题,结合溶剂萃取法操作简单、成本低等优势,利用相似相溶的原理,以CS2为溶剂设计了一种用溶剂法提纯硫磺的工艺。通过干燥时间考察了硫磺渣中的含水量,以硫磺产率为指标,考察了硫磺渣干燥时间、液固比、浸取时间、浸取温度和球磨粉碎对硫磺产率的影响,并通过XRD及ICP分析了纯化后硫磺的纯度。结果表明,硫磺渣干燥时间为60 min、液固比(体积质量比,m L/g)为8∶1、浸取时间为30 min、浸取温度为30℃及球磨成粉时,硫磺产率最佳。相较于传统的熔融法(85.7%)和气化法(85.37%)工艺,溶剂法工艺提纯硫磺后产率高达87.8%,提高了2.5%左右,且提纯后硫磺的纯度高达99.89%。该溶剂法提纯硫磺的工艺具有产率较高且纯度高、操作简单的优势,为有效处理硫磺提纯提供了技术路线,同时在硫磺纯化方面具有广阔的应用前景。

超声辅助低共熔溶剂法提取太白贝母总黄酮及其抗氧化活性研究

采用超声辅助低共熔溶剂法提取太白贝母总黄酮,以太白贝母总黄酮提取率为考察指标,通过单因素实验和响应面法对提取工艺进行了优化,并通过DPPH自由基清除实验和ABTS自由基清除实验研究了其抗氧化活性。结果表明,在超声功率为69 W、料液比为1∶18(g∶mL)、超声温度为79℃、超声时间为27 min的最优工艺条件下,太白贝母总黄酮提取率可以达到17.7004%,与预测值相差极小;太白贝母总黄酮是一种强抗氧化剂,对DPPH自由基、ABTS自由基具有较强的清除能力,在浓度为16 mg·mL^(-1)时,清除率分别达到82.15%、90.42%,与VC无明显差异。超声辅助低共熔溶剂法操作简便、提取率高,适用于太白贝母总黄酮的提取。该研究为太白贝母药材资源的开发利用提供了参考。

响应面法优化有机溶剂提取虾青素的工艺研究

为确定有机溶剂提取虾青素的最佳条件,本研究选用破壁后的雨生红球藻,提取选用有机溶剂,以物料比、皂化液浓度、皂化时间、虾青素提取时间为指标,采用单因素和响应面法优化实验条件。结果表明,最佳工艺参数为:提取溶剂为乙酸乙酯-乙醇(1∶1)、料液比为1∶288(g∶mL)、皂化液浓度为0.05mol·L^(-1)、皂化时间为12h,虾青素平均提取率为3.32%。采用响应面法优化有机溶剂提取虾青素的工艺具有可行性,且提取的虾青素纯度较高,杂质少,可用于虾青素的提取。

天然产物提取技术的实验设计与优化

针对我校应用化学专业实验部分教学内容单一性较强,授课过程学生参与的主动性较差,不能有效践行以学生为本的教育理念,开发了从西红柿、菠菜、橙皮、红辣椒等天然产物中提取有用成分的综合设计性实验技术。学生可以自由选择天然产物,组成2~3人团队,通过文献查阅、实验方案设计、有用成分的提取与分离、产品检测、数据分析等教学环节,培养学生运用应用化学专业的理论知识来解决生活实际问题的能力。将生活实际转化为综合性设计性实验内容,强化专业实验技能培养,增强应化专业学生实践能力,从而满足工程教育专业认证背景下对于人才培养的要求。

银耳多糖对麦醇溶蛋白纳米体系的影响及复合物的特性研究

该研究是以提高麦醇溶蛋白(gliadin,Gli)纳米颗粒(gliadin nanoparticles,GNPs)稳定性为目标,利用银耳多糖(Tremella fuciformis polysaccharides,TFPs)的乳化性能,探究TFPs添加量对GNPs稳定性的影响。采用反溶剂法制备银耳多糖和麦醇溶蛋白复合载体颗粒(gliadin-Tremella fuciformis polysaccharides composite nanoparticles,G/T NPs),并利用纳米粒度仪、傅里叶变换红外光谱仪、热场发射扫描电镜对G/T NPs的粒径和电位、相互作用、微观结构进行分析。结果表明,TFPs和Gli之间通过静电作用力和氢键作用力相结合,形成GNPs在内、TFPs外层附着的复合颗粒;TFPs的添加能够有效提高GNPs体系的稳定性,减少颗粒之间的聚集,制得的G/T_(4∶1)NPs的平均粒径、多分散指数(polydispersion index,PDI)、ζ-电位分别为(198.5±2.6)nm、0.269±0.005、(36.7±0.6)mV,且具有pH响应性。该研究为后续构建疏水营养成分的包埋和运载体系奠定了基础。

黄连生物碱超声辅助低共熔溶剂提取工艺优化

目的优化黄连生物碱超声辅助低共熔溶剂提取工艺。方法以葡萄糖-乳酸(1∶5)为低共熔溶剂。在单因素试验基础上,以提取时间、含水量、液料比为影响因素,生物碱得率为评价指标,Box-Behnken响应面法优化提取工艺。结果最佳条件为提取时间35 min,含水量26%,液料比33∶1,生物碱得率为7.22%。结论该方法稳定可靠,切实可行,可为黄连开发利用提供参考。

盐酸艾司洛尔残留溶剂测定方法优化

目的:优化盐酸艾司洛尔残留溶剂检测方法,以便于内部质量控制。方法:使用气相色谱顶空进样方式,选择合适的顶空平衡温度和时间,降低样品对仪器的污染,优化溶剂比例,降低基质效应,调整了载气流速和分流比,采用极性毛细管柱程序升温的方法,延长了高温段保持时间等,并进行方法学验证。结果:乙醚、乙酸乙酯、甲醇、甲苯均能得到有效分离,精密度良好,峰面积和质量浓度均呈很好的线性关系,分别考察样品加标50%、100%、150%3个浓度的准确度,平均回收率均能在94.8%~105.6%。结论:该方法准确,灵敏度高,克服了《中国药典》方法的缺陷,可用于盐酸艾司洛尔残留溶剂检测。

超声辅助低共熔溶剂制备咖啡果皮可溶性膳食纤维

为进一步探索制备咖啡果皮中可溶性膳食纤维的绿色新方法。本研究建立了一种省时、高效、环保的超声辅助低共熔溶剂(UAE-DESs)制备咖啡果皮可溶性膳食纤维(SDF)的方法,并通过单因素试验和响应面试验优化了其工艺参数。采用加热法制备了8种氯化胆碱基的DESs作为提取溶剂,并与传统水提法作对比。结果表明:氯化胆碱与尿素摩尔比为1∶2的DES体系制备的咖啡果皮SDF得率最高,为10.10%±0.11%,显著高于传统水提法(6.50%±0.22%)。通过单因素实验,探讨了DES组成(摩尔比、含水量、液固比)和超声波处理(超声功率、超声时间)对咖啡果皮SDF得率的影响。在此基础上,采用响应面法(RSM)结合Box-Behnken设计(BBD)对SDF得率进行优化,考察DES含水量、液固比、超声功率和超声时间对SDF得率的影响。根据RSM的优化结果,确定最佳制备条件为:DES含水量为39.91%,液固比为32.37 mL/g,超声功率为305.20 W,超声时间为33.80 min,在此条件下,咖啡果皮SDF得率最大,为10.74%±0.14%,与其预测值10.80%接近。因此,DES作为一种高效、无污染的绿色溶剂,可用于咖啡果皮SDF的制备。本研究结果将为咖啡果皮可溶性膳食纤维的制备提供新思路和理论参考,并在咖啡副产物的增值利用、生产新型高附加值产品以及开发天然功能性食品等方面具有潜在的应用前景。

溶剂热法合成NiFe_(2)O_(4)纳米颗粒及其光催化降解亚甲基蓝实验

本文以3种溶剂合成了不同形貌特征的尖晶石型NiFe_(2)O_(4)纳米颗粒,并利用紫外-可见分光光度计测试了其对工业标准染料亚甲基蓝(MB)的降解效率。结果表明,使用乙二醇为溶剂合成的NiFe_(2)O_(4)纳米颗粒,催化剂用量为4g·L^(-1)、亚甲基蓝初始浓度为20mg·L^(-1)、pH值为2~4、温度为50℃、H_(2)O_(2)投加量为20mL·L^(-1),在紫外光源照射60min左右时,超过95.4%的亚甲基蓝染料被降解。表征结果表明,使用乙二醇为溶剂合成的NiFe_(2)O_(4)有着轮廓清晰的纺锤体性质,伴随着多孔性以及高透明度,可以有效地对紫外光进行吸收,更快地形成电子-空穴对,对亚甲基蓝进行分解。通过自由基淬灭实验对制备的NiFe_(2)O_(4)纳米粒子的光催化机理进行了研究,并通过重复循环实验研究了制备的NiFe_(2)O_(4)纳米粒子的稳定性。

赤泥中稀土提取与分离技术研究进展

稀土元素被誉为“工业维生素”,具有优异的磁、光、电性能。随着新能源汽车等新兴行业对稀土需求量的不断增加,稀土资源日益紧缺,从二次资源中回收稀土已成大势所趋。作为一种重要的二次资源,赤泥的产量高、堆存量大、稀土含量较高。本文介绍了赤泥中稀土元素的赋存状态,概述了从赤泥中提取分离稀土元素的湿法浸出工艺和火法-湿法联合工艺;介绍了溶剂萃取法和离子交换法两种分离工艺的研究现状,对比分析了不同处理工艺的优缺点,并通过比较不同工艺的优劣,指出降低回收成本、提高环境效益是未来赤泥资源化利用研究的重要方向。

包覆低共熔溶剂的聚苯乙烯微胶囊吸附Li^(+)的性能研究

为实现绿色、低成本从海水中提锂的目标,采用同轴共流微流体技术结合溶剂挥发法制备包覆有低共熔溶剂(甲基三辛基氯化铵/癸酸)的聚苯乙烯微胶囊。所制备的微胶囊颗粒呈均一的球形。将该微胶囊用作萃取Li^(+)吸附剂,系统研究了吸附时间、吸附温度、溶液pH、初始锂浓度和固液比对Li^(+)吸附量和萃取率的影响。结果表明在吸附Li^(+)水溶液时,微胶囊对Li^(+)的最大吸附量为32 mg·g^(-1)。碱性条件时微胶囊对模拟海水中的Li^(+)吸附分配比为10.22 L·g^(-1)。