α-萘乙酸与β-萘酚在含夹带剂超临界CO2中溶解度的研究

采用流动法，以乙醇、丙酮、环己烷为夹带剂，测定了固体溶质α-萘乙酸在超临界CO2中的溶解度，并与相应的β-萘酚的溶解度进行了对比研究。试验结果表明，溶质溶解度随压力的升高而增大；高压下高温萃取有利，低压下低温萃取有利；无论何种夹带剂的加入，均能在一定程度上增加溶质的溶解度，但对于极性溶质，极性夹带剂对其溶解度的提高作用更加显著。     

关于超临界萃取过程中使用夹带剂的研究

建立了一套研究夹带剂的超临界萃取装置。在胡罗卜素及罗汉果糠甙的萃取中,分别使用丙酮和乙醇做夹带剂,研究它们对溶解度、收率及选择性的影响。     

夹带剂对超临界CO2萃取重结晶岩白菜素的影响

以70%的岩白菜素为原料,采用超临界CO2萃取重结晶岩白菜素,考察了甲醇、乙醇、丙酮和乙酸乙酯4种夹带剂对超临界CO2萃取重结晶岩白菜素的结晶率、纯度、形貌和IR图谱等的作用规律.结果表明,在萃取结晶压力为15 MPa、萃取温度为55℃、萃取时间为50 min、CO2流量为15 L·min-1的条件下,乙醇作夹带剂时重结晶纯化岩白菜素的综合效果最好,结晶率达60%以上、重结晶纯度达92%以上,且能保持晶体的优良晶型和结晶品质,综合评价后优选乙醇为夹带剂.     

聚谷氨酸高吸水树脂的表征

对聚谷氨酸高吸水树脂进行了IR1、HNMR、热稳定性、吸水性能的分析,结果表明:在3 305 cm-1为O—H伸缩振动带,1 646 cm-1为羧基中—C O的伸缩振动带,1 593 cm-1为NH弯曲和C—N伸缩振动的偶合,1 111 cm-1为侧链脂肪醚C—O—C的非对称伸缩振动,2 876 cm-1为γ-PGA主链上—CH2的C—H键的对称伸缩振动;3.628处出现了聚乙醇缩水甘油醚上的H的化学位移,说明聚乙二醇缩水甘油醚与聚谷氨酸已充分交联;聚谷氨酸高吸水树脂具有良好的热稳定性及吸水性能。     

对羟基苯甲酸甲酯在含夹带剂超临界CO2中溶解度的研究

采用流动法测定了对羟基苯甲酸甲酯在含和不舍夹带剂的超临界CO2中的溶解度,实验所用夹带剂分别为正己烷、乙醇、丙酮及混合夹带剂正己烷 丙酮(摩尔比为1：1),夹带剂的摩尔分数均为0．035。论述了温度、压力和夹带剂对固体溶解度的影响,然后用化学缔合模型关联了实验数据,实验值与计算值吻合良好。     

应用光谱分析技术研究榕树叶吸附铀的机理

为了了解榕树叶吸附铀的过程机制,改善榕树叶吸附能力,提高铀的去除率,采用红外光谱仪、扫描电镜仪、X射线衍射仪、X射线光电子能谱仪等现代分析仪器探讨榕树叶吸附铀的机理。结果表明:榕树叶主要由碳水化合物、木质素及纤维素等组成,其吸收峰是由C=O的伸缩振动峰、苯环的骨架振动峰、苯羟基中C—O的伸缩振动峰构成;吸附UO22+后,榕树叶细胞的表面形态发生了改变,表面上分布的空隙和空洞减少,呈现出较多电子不透明的微小颗粒,相互黏合在一起,但没有形成新晶形结构,只是吸附过程中部分晶相转变为非晶相,其基本结构仍保持完整;因此榕树叶吸附铀的机理为表面络合吸附机理,UO22+主要与细胞表面上—OH、C=O、P—O及Si=O等基团螯合,形成配合物。     

CYPERM/MCT-β-CD超分子包合物的制备及光谱研究

借助计算化学分析手段,将包合物的IR和Raman光谱与B3LYP/6-31G(d)水平下的计算光谱对比,研究分析可用于棉织物防蚊驱虫整理的1-氯均三嗪-β-环糊精(MCT-β-CD)与高效氯氰菊酯的包合物。包合单体由环糊精的大口端插入其内腔。在实验谱图与计算谱图中观测到C=O伸缩振动峰,说明包合物分子的一氯均三嗪基团不是以C-O-盐的形式存在,而是以C=O双键的形式存在。     

不同类型层状硅酸盐宝玉石矿物的近红外光谱研究

目前宝石红外光谱的研究主要集中在中红外波段,对近红外区间的研究相对较少.以层状硅酸盐宝玉石矿物为研究对象,测试分析了该类宝玉石矿物的近红外光谱特征,得出以下结果:1:1型矿物Si-O基团伸缩振动倍频峰主要位于4600 cm-1附近;2:1型矿物Si-O基团伸缩振动倍频峰主要位于4500 cm-1附近;而2:1:1型矿物由于Si-O基团与[OH]基团合频振动,峰值主要位于4400 cm-1附近.高岭石、蛇纹石、滑石、叶腊石、绿泥石、葡萄石中H2 O弯曲和伸缩振动组合频位于5150 cm-1附近.此类合频峰在层状硅酸盐宝玉石矿物的三种类型中均存在.羟基O-H伸缩振动的倍频位于滑石7223 cm-1、叶蜡石7201 cm-1处,这里主要存在于2:1型的矿物中.     

排斥萃取过程初探及其应用

研究了向水中加入盐类形成的复合萃取剂对丙酮 乙酸乙酯、乙醇 水 乙酸乙酯、水 丁酮三组体系的萃取分离效果，并与水萃取剂的分离效果相比较，发现盐组分可以增大萃取剂对溶质的选择性系数２６～１３００倍，达到强化萃取的目的。提出其强化萃取过程为排斥作用，并探讨排斥作用机理。进一步比较了本研究方法与传统方法对三组体系的分离能耗     

傅立叶变换近红外光谱技术应用于聚氯乙烯质量分析的可行性研究

近红外光是指介于可见光与中红外光之间的电磁波 ,美国ASTM规定其波长范围为 :780～ 2 5 2 6nm。物质分子中C -H ,N -H ,O -H和C =O等基团振动频率的合频与倍频的吸收在近红外区 ,因此近红外技术比较适合于分析与这些基团有直接或间接关系的成分。聚氯乙烯粘数、表观密度和白度     

Study on elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide

The elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide has been studied. Some factors influencing elution recovery, including entrainer, temperature, pressure and the flow rate of supercritical fluid CO₂ are discussed in this work. The addition of a small amount of entrainer, such as ethanol, triethanolamine and their mixture to supercritical CO₂ can cause dramatic effects on the elution ability. The results show that the salicylic acid can be only slightly eluted from the resin with supercritical CO₂ alone with temperatures ranging from 307.15 to 323.15 K and pressures ranging from 10 to 30 MPa. Meanwhile, with the same T, P conditions, 40.58% and 73.08% salicylic acid can be eluted from the ion exchange resin with ethanol and ethanol + triethanolamine as the entrainer, respectively. An improved PR equation of state with VDW1 mixing rules is used to calculate the elution recovery of salicylic acid in supercritical CO₂ and the results agree well with the experimental data.     

EFFECTS OF ENTRAINERS ON THE PHASE EQUILIBRIUM OF SUPERCRITICAL FLUID EXTRACTION PROCESS

A flow apparatus was set up for measuring the solubility of a solid solute in a supercritical fluid withthe presence of a small amount of entrainer.The solubilities of biphenyl,diphenylamine and benzoic acid insupercritical carbon dioxide with one of the selected entrainers which were ethanol,acetone and n-hexanerespectively,were obtained in the pressure range of 10—32 MPa and the temperature range of 308—318K.Asolvolytic association theory has been proposed to explain the mechanism of entrainer effect,and theexperimental results were reasonably analysed.According to the solvolytic association theory,the association equa-tion of state was adopted to correlate the experimental data with good accuracy.     

Measurement of entrainer effects of water and ethanol on solubility of caffeine in supercritical carbon dioxide by FT-IR spectroscopy

The solubilities of caffeine in supercritical CO₂, supercritical CO₂ + water, supercritical CO₂ + ethanol, and supercritical CO₂ + water + ethanol were measured with a circulation-type apparatus combined with an on-line Fourier transform infrared (FT-IR) spectrometer at 313.2 K and 15.0 MPa. The solubilities of caffeine were determined with the peak absorbances of caffeine at 1190 cm⁻¹. The solubilities of caffeine increase until water is saturated in supercritical CO₂. The maximum increase rate is 22%. In CO₂ + caffeine + ethanol system, the solubilities of caffeine increase with increasing the concentration of ethanol. The solubility of caffeine becomes five times when 1000 mol m⁻³ of ethanol is added. In CO₂ + caffeine + water + ethanol system, the solubilities of caffeine are smaller than those with single entrainer of water or ethanol. The shape of the peaks of two CO stretching bands for caffeine were changed by the addition of ethanol. It was confirmed that the interaction species of caffeine interacting with ethanol are produced by deconvolution of the CO stretching bands. The enhancement of solubility for caffeine in supercritical CO₂ by the addition of ethanol is due to the hydrogen bonding between caffeine and ethanol.     

SO~(2-)_4 改性交联蒙脱土固体酸催化合成水杨酸正丁酯

制备了SO2-4改性硅锆双组分交联蒙脱土固体酸催化剂(SO2-4/SiZrM),用于水杨酸(C7H6O3)和正丁醇(C4H10O)的酯化反应,与传统酯化反应催化剂浓硫酸、磷钨酸、硫酸铁铵以及其他单组分交联剂交联的蒙脱土做酯化反应的催化剂相比,SO2-4/SiZrM有更好的催化活性。考察了带水剂的选择、酸醇量比〔n(C7H6O3)∶n(C4H10O)〕、催化剂用量〔w(SO2-4/SiZrM)〕、反应时间(t)、反应温度(θ)对催化合成水杨酸正丁酯(C11H14O3)的影响,并对合成的产物进行了折光率、红外光谱分析。酯化反应的最佳条件为:C4H10O为带水剂、n(C7H6O3)∶n(C4H10O)=1∶1 65、催化剂占酸投料质量的百分比为w(SO2-4/SiZrM)=6 5%、t=6h、θ=120～135℃,水杨酸的转化率可达88 22%,产物中w(C11H14O3)>99 9%。     

Supercritical CO2 extraction of pigment components with pharmaceutical importance from Chlorella vulgaris

BACKGROUND: Chlorella vulgaris is a green microalgae that contains various pigment components of carotenoids and chlorophylls. Supercritical CO₂ is widely used for extraction of pharmaceutical compounds because it is non‐oxic and easily separated from extracted material by simply depressurizing. In this work, pharmaceutical compounds from Chlorella vulgaris have been extracted using supercritical CO₂ with or without entrainer at various extraction conditions. RESULTS: Based on high performance liquid chromatography (HPLC) analysis, the extracts contained pigment components, such as lutein, β‐carotene, chlorophyll a and b. Higher extraction pressure and temperature promoted higher lutein extraction by supercritical CO₂. The optimum pressure and temperature for extraction were obtained as 50 MPa and 80 °C. Ethanol as an entrainer was more effective than acetone for the extraction of pigment components. Pigment components in the extract obtained by supercritical CO₂ with and without entrainer were compared with the extract obtained by a conventional extraction method. CONCLUSION: Supercritical CO₂ has been successfully applied for the extraction of pigment components from Chlorella vulgaris. Supercritical CO₂ enabled high selectivity for lutein extraction; however, the lutein yield was lower than that obtained by extraction using supercritical CO₂ with ethanol and soxhlet. Copyright © 2008 Society of Chemical Industry     

Modeling of drug solubility in supercritical carbon dioxide using equation of state based on hole theory with molecular surface charge density

Equation of state based on hole theory with molecular surface charge density was developed for the modeling of drug solubility in supercritical carbon dioxide. In the hole theory, the density change of supercritical carbon dioxide can be represented by the number of holes in the system. The molecular interaction energy parameter was estimated using the interactions of segments on the molecular surface given by a quantum calculation using conductor-like screening model. The only one parameter, coordination number around a molecule was fitted to the experimental data of the drug solubility in supercritical carbon dioxide. The solubilities of the eighteen drugs in supercritical carbon dioxide were modeled by the equation of state with the molecular surface charge density. The effect of the molecular pair for the coordination number on the correlated results was investigated. It is found that the results using the fitted parameter of the solute–solute pair coordination number result in the modeling performance better than those of carbon dioxide–solute coordination number. The results of the modeling of drug solubility in supercritical carbon dioxide are compared with the experimental data. The average absolute relative deviation between the experimental and calculated results of the solubility for the drug composed of C, H and O atoms acetylsalicylic acid, benzoic acid, ferulic acid, (S)-naproxen, p-benzoquinone, propyl gallate, salicylic acid and vanillic acid is 0.38 smaller than those for compounds including N, F, I and S atoms, amical-48, benzocaine, caffeine, carbamazepine, (±)-flurbiprofen, methimazole, phenazopyridine, theobromine, theophylline and uracil, 0.59.     

Supercritical fluid extraction of sunflower seed oil with CO2-ethanol mixtures

The effect of ethanol addition to supercritical carbon dioxide (SC-CO₂), up to 20%, on sunflower seed oil extraction over the range of 150 to 350 bars and 42 to 80°C was studied. A nonrecirculating home-made bench-scale system was used as extraction equipment. The oil-SC-CO₂-ethanol mixture was reduced to atmospheric pressure in a test tube, where two phases, oil and ethanol, were obtained and ethanol-saturated CO₂ was liberated to the atmosphere. Results show that sunflower oil solubility in SC-CO₂ greatly increases with addition of ethanol as entrainer over the whole range of pressure and temperature conditions. Some phospholipids are co-extracted at levels directly proportional to the added ethanol. Moreover, a large amount of phospholipids was recovered in the ethanolic phase. Acidity of the extracted oil with ethanol as entrainer was lower than that without alcohol. Part of the free fatty acids was found in the ethanolic phase.     

Optimization of supercritical fluid extraction of phytosterol from roselle seeds with a central composite design model

Recovery of phytosterol from roselle (Hibiscus sabdariffa L.) seeds via supercritical carbon dioxide extraction modified with ethanol was investigated at pressures of 200–400 bar, temperatures from 40 to 80 °C and at supercritical fluid flow rates from 10 to 20 ml/min. It was found that an entrainer such as ethanol could enhance the solubility and extraction yield of roselle seed oil from the seed matrix, compared to values obtained using supercritical CO₂. After a typical run (holding period of 30 min, continuous flow extraction of 3 h), the results indicate that the oil recovery was optimal with a recovery of 108.74% and a phytosterol composition of 7262.80 mg kg^?1 at relatively low temperature of 40 °C, a high pressure of 400 bar and at a high supercritical fluid flow rate of 20 ml/min in the presence of 2 ml/min EtOH as entrainer. The solubility of roselle seed oil increased with temperature at the operating pressures of 200, 300 and 400 bar. Supercritical fluid extraction involved a short extraction time and the minimal usage of small amounts of entrainer in the CO₂.     

Supercritical carbon dioxide extraction of astaxanthin from Paracoccus NBRC 101723: Mathematical modelling study

Astaxanthin (AX) is a secondary metabolite that accumulates inside the cell during Paracoccus fermentation. The fermentation biomass was extracted using supercritical carbon dioxide (SC-CO₂). The solubility parameter of AX, CO₂ and entrainer solvents was calculated and validated with experimental results. The pressure and particle size of the biomass had a significant effect on the extraction of AX. A maximum recovery of 963.33 μg/g of AX was obtained after SC-CO₂ extraction at 40ºC, 350 bar and a run time of 60 min with ethanol (20% v/w) as an entrainer. Further, the experimental data has been modelled using non-linear regression analysis method.