计算机模拟溶剂对对苯二酚晶习的影响

针对苯二酚的单晶结构,采用BFDH和AE模型对对苯二酚的理论晶习进行了模拟,然后利用分子动力学模拟计算了对苯二酚各晶面在水溶液中与水分子的相互作用能,并利用修正的AE模型对水溶液可能出现的晶习进行了模拟计算,计算结果与实际晶习一致。     

球形和片状氯化钠晶习调控研究

晶习会影响晶体的流动性、堆密度等多种性质,目前氯化钠主要以立方晶习存在,导致其在包装和运输等过程中极易结块。为了解决立方氯化钠的结块问题,开发了多品种食用盐,研究了减压蒸发结晶实验中的多个操作条件对氯化钠晶习的影响,探索了立方氯化钠在甲醇-水混合溶剂中的晶习变化,并研究了小规模液体蒸发对于氯化钠晶体生长的影响。结果表明：在减压蒸发结晶实验中,使用优化的工艺条件能够得到球形化较好的氯化钠球形晶体;当用甲醇质量分数为0.5左右的甲醇-水混合溶剂溶解立方形氯化钠晶体时,可获得球形晶习;而通过使用小规模液体蒸发的方法可以得到粒度较大的片状晶体。     

新型甜味剂纽甜结晶工艺优化研究

通过过程分析和优化,制备了纯A晶型的纽甜长棒状晶体。与细针形晶体比较,长棒晶体在堆密度、水分、收率以及粒度分布等方面占有优势。考察了过饱和度、晶种量、搅拌速率、溶剂配比等对纽甜晶习的影响,确定了纽甜结晶工艺关键影响参数。     

双水相微胶束萃取对苯二酚研究

采用非离子型表面活性剂辛基酚聚氧乙烯醚(Triton X-114)组成的双水相系统(ATPS)萃取对苯二酚,依据胶束分相和分配,实现对苯二酚的萃取和分离。讨论表面活性剂浓度对萃取率的影响,尝试用反萃取方法回收进入微胶束相的对苯二酚。结果表明:双水相微胶束对对苯二酚的萃取率取决于Triton X-114的浓度,双水相微胶束对对苯二酚的萃取率随Triton X-114浓度的增加而增大;反萃取时溶液的pH值等因素对反萃取率的影响很大,通过调节pH值可以使反萃取率增大。     

活性炭对对苯二酚的吸附试验研究

在静态条件下,采用活性炭对对苯二酚废水进行处理,比较了不同条件下活性炭对对苯二酚废水的吸附效果,确定了处理废水的pH值、活性炭用量、振荡时间、温度、废水中对苯二酚浓度、振荡速率以及电解质对吸附效果的影响。试验结果表明:在pH值为6.5、活性炭投加量为35g/L、振荡时间3.5h、温度35℃左右的条件下,对质量浓度为100mg/L的对苯二酚废水的处理效果最好,去除率可达99%。     

《化工学报》2006年第57卷第3期目次

综述与专论子空间模型辨识方法综述热力学溶剂对对苯二酚晶体晶习的影响传递现象板翅式换热器封头结构物流分配的PIV实验研究垂直圆管内液氮流动沸腾的理论模型及数值模拟EHD强化相变换热同轴圆柱特征电极的理论分析一种氨水垂直降膜吸收传质模型恒热流工况下管内对流换热火用传递特性三元混合制冷工质变组成容量控制空调超临界流体萃取天然产物传质模型非共沸混合物微尺度管内流动沸腾特性多相流汽—液—固流动沸腾系统混沌时间序列的遗传算法全局建模下倾管中活塞流液塞长度波动特性上行气固两相流充分发展段流动行为的相似特性用全息…     

阴-阳离子有机坡缕石对对苯二酚的吸附行为

采用微波辅助法制备了一系列阴-阳离子表面活性剂改性坡缕石,研究了改性坡缕石对水中对苯二酚的吸附.结果表明,经阴-阳离子表面活性剂改性后的坡缕石对对苯二酚的吸附能力远大于坡缕石原土及阳离子表面活性剂改性的坡缕石.改性坡缕石对对苯二酚的最大吸附量为137.5 mg/g.等温吸附过程可以用Langmuir方程进行较好拟合,热力学函数计算表明,吸附剂对对苯二酚的吸附是自发的放热过程,吸附热和熵变分别为-93.582 kJ/mol和-299.32 J/mol·K,吸附自由能随温度的升高而增加.     

聚组氨酸修饰玻碳电极的制备及污水中对苯二酚测定的研究

用循环伏安法研究了聚组氨酸修饰玻碳电极的制备及其对对苯二酚(HQ)的电催化作用。讨论了支持底液、pH、扫速等对对苯二酚测定的影响,优化了实验条件。实验表明,在最优条件下,对苯二酚在修饰电极上的峰电流与其浓度在1.0×10-5~2.3×10-4mol/L内呈良好的线性关系,最低检测限为7.2×10-7mol/L。此方法可应用于实际样品的测定。     

硫酸氢氯吡格雷球形结晶工艺及其生长机理

本文测定了硫酸氢氯吡格雷Ⅰ、Ⅱ晶型在仲丁醇中的溶解度,通过过程分析和优化,制备了纯Ⅰ晶型的硫酸氢氯吡格雷球形晶体。与非球形晶体比较,球形晶体在堆密度、流动性、粒度分布以及稳定性等方面均占优势。本文考察了不同温度、残留溶剂对硫酸氢氯吡格雷晶习与晶型的影响,研究了硫酸氢氯吡格雷球形结晶过程晶体的生长机理。     

纳米金修饰电极对对苯二酚的电催化性能研究

本文使用纳米金制备出三种纳米金修饰电极。考察了不同电极对对苯二酚响应特性及响应线性范围。实验结果表明:在pH值=6.0的磷酸盐缓冲溶液中,使用滴涂法制备的纳米金/壳聚糖复合膜修饰电极对对苯二酚的催化响应更为显著,在0.2×10-4~1.6×10~(-4)mol/L浓度范围内,其氧化峰电流与对苯二酚浓度呈良好的线性关系,具有制备对苯二酚传感器的前景。     

Crystal modification of rifapentine using different solvents

Rifapentine crystals with different habits were prepared by recrystallization from selected solvents, such as methanol, ethanol, chloroform, and acetic acid. Scanning electron microscopy, X-ray powder diffractometry, infrared spectrometry, and differential scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The comparative dissolution behaviors of the newly developed crystals and of rifapentine without being treated were also studied. Results show that the newly developed crystals were different from each other with respect to physical properties but were identical chemically. Needle-shaped crystals were obtained from methanol, ethanol, and chloroform solvents, and the block-shaped crystals were obtained from acetic acid solvent. X-ray diffraction spectra and differential scanning calorimetry investigation on those developed crystals clearly indicate that rifapentine has different crystal structure modification. When the crystal was obtained from acetic acid, the change of crystal habit was originated from the crystal structure modification. The dissolution rate of newly developed crystals was found to be higher than that of rifapentine without being treated. However, the modified crystal obtained from acetic acid shows the lower dissolution rate than crystals obtained from other solvents.     

Crystal modification of rifapentine using different solvents

Rifapentine crystals with different habits were prepared by recrystallization from selected solvents, such as methanol, ethanol, chloroform, and acetic acid. Scanning electron microscopy, X-ray powder diffractometry, infrared spectrometry, and differential scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The comparative dissolution behaviors of the newly developed crystals and of rifapentine without being treated were also studied. Results show that the newly developed crystals were different from each other with respect to physical properties but were identical chemically. Needle-shaped crystals were obtained from methanol, ethanol, and chloroform solvents, and the block-shaped crystals were obtained from acetic acid solvent. X-ray diffraction spectra and differential scanning calorimetry investigation on those developed crystals clearly indicate that rifapentine has different crystal structure modification. When the crystal was obtained from acetic acid, the change of crystal habit was originated from the crystal structure modification. The dissolution rate of newly developed crystals was found to be higher than that of rifapentine without being treated. However, the modified crystal obtained from acetic acid shows the lower dissolution rate than crystals obtained from other solvents.     

溶剂与杂质对11α羟基-16α,17α-环氧黄体酮晶习的影响

The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α, 17α-epoxyprogesterone (HEP) grown from solution were studied by scanning electron microscope. Long prismatic crystals were produced when HEP was crystallized from pure acetone and N,N-dimethylformamide, while blocky crystals were produced from pure chloroform by cooling crystallization. One kind of isomorphic impurity, 16α, 17α-epoxyprogesterone (EP)was selected to examine its effect on the HEP crystal habit. When the content of EP in the mother liquor is very high (55.45%, solvent free basis), the habit of produced HEP crystals was greatly modified from prismatic to octahedral. The differential scanning calorimetry and X-ray powder diffraction analyses showed that the change of crystal habit was originated from the crystal structure modification.     

溶剂与杂质对11α-羟基-16α,17α-环氧黄体酮晶习的影响

The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α, 17α-epoxyprogesterone （HEP） grown from solution were studied by scanning electron microscope. Long prismatic crystals were produced when HEP was crystallized from pure acetone and N,N-dimethylformamide, while blocky crystals were produced from pure chloroform by cooling crystallization. One kind of isomorphic impurity, 16α, 17α-epoxyprogesterone （EP） was selected to examine its effect on the HEP crystal habit. When the content of EP in the mother liquor is very high （55.45%, solvent free basis）, the habit of produced HEP crystals was greatly modified from prismatic to octahedral. The differential scanning calorimetry and X-ray powder diffraction analyses showed that the change of crystal habit was originated from the crystal structure modification.     

Effect of mixed solvent on structural,morphological, and optoelectrical properties of spin-coated TiO2 thin films

Nanocrystalline TiO₂ anatase thin films have been synthesized from alkoxide solution via sol–gel spin coating method. The effects of different solvents of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol as well as those of mixed solvents on crystal structure, thermal behavior, morphology, and optoelectrical properties were investigated. It was found that not only the occurrence of rutile with anatase phase was solvent dependent, but also the morphology and optoelectrical properties of the films were strongly affected by solvent type. However, using two different types of alcohols as a single solvent brings the advantages of both solvents. Also, some unique properties in mixed solvent samples could be achieved. The viscosity, gel time, boiling point, possible complexes, dipole moment, and chain length of the solvent affect the packing density, lattice distortion, interfaces, thickness, optical band gap, refractive index, and extinction coefficient.     

A systematic study of solvent effect on the crystal habit of dirithromycin solvates by computer simulation

The crystal habits of five dirithromycin solvates were employed to unravel the solvent effect by using the modified attachment energy (AE) model. Solvents with different polarity and hydrogen bond donor/acceptor ability (acetone, 1-propanol, acetonitrile, water and cyclohexane) were studied. The good consistency between experimental results and predictions confirmed the applicability of modified AE model. Simulation results showed that all solvates underwent a change in morphological importance (MI) of crystal faces except for the cyclohexane trisolvate. A detailed analysis of the results indicated that the polar solvent had a stronger interaction with crystal face than the non-polar solvent due to the formation of hydrogen bond. Furthermore, crystals with similar structure in different solvents exhibited different aspect ratios. The computer-aided study approach in this work could be helpful to control the morphology of crystal by tailor-made solvents or additives.     

Habit modification of tamoxifen crystals using antisolvent crystallizations

The crystal habit of tamoxifen was modified using antisolvent crystallization techniques. Tamoxifen was crystallized from organic solvents using two different antisolvents (water and carbon dioxide). The habit of the precipitated crystals was modified by changing the process conditions, such as the solution and antisolvent mixing rate, the organic solvent, the presence of ultrasonic waves, and the addition of external additives. Particle size, crystal habit, particle aspect ratio and powder XRD patterns of the precipitated tamoxifen crystals were measured. With water as the antisolvent, the particle size of tamoxifen was significantly reduced compared to that of the raw material. When the antisolvent was carbon dioxide, the particle size was an order of magnitude greater than that of the raw material. The average aspect ratio of the tamoxifen crystals ranged from 1.8 to 16.2. The presence of ultrasonic waves caused a significant reduction in the aspect ratio, as well as the particle size. Furthermore, the addition of external additives was found to influence the crystal habit of tamoxifen.     

Solvent effect on microstructure of yttria-stabilized zirconia (YSZ) particles in solvothermal synthesis

Using methanol or methanol/2-propanol mixtures as reaction media, yttria-stabilized zirconia (YSZ) particles were synthesized with a solvothermal route. The particles were characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser diffraction technique, and nitrogen adsorption isotherms. Results indicated that cubic/tetragonal YSZ nanocrystals with crystal size lower than 5 nm were obtained and the crystal size depends on solvent composition, reaction temperature and reaction time. For the same reaction temperature and reaction time, the solvent composition also controls YSZ crystal agglomeration behaviour. According to the DLVO theory and analysis of experimental results, the solvent effect on microstructures of YSZ particles in solvothermal synthesis has been discussed. In addition, the mechanism of particle microstructure evolution during solvothermal synthesis has been suggested.     

Recrystallization of sulfathiazole and chlorpropamide using the supercritical fluid antisolvent process

The supercritical antisolvent (SAS) process was used to modify the solid–state properties of sulfathiazole and chlorpropamide. Acetone, methanol, and ethyl acetate were employed as solvents for the pharmaceutical compounds, and carbon dioxide was used as an antisolvent. The effects of process parameters on the precipitate crystals such as carbon dioxide injection rate, type of solvent, and temperature were investigated. The SAS processed crystals show more ordered appearances with clean surfaces and sharp angles compared with the unprocessed particles. The crystal habit changed from tabular to acicular when the carbon dioxide injection rate increased. The X-ray diffraction patterns of the two compounds revealed variations of crystallinity and crystal orientations depending upon the injection rate, where the degree of crystallinity was found to be inversely proportional to the rate of injection. The analysis of differential scanning calorimetry indicated that both the injection rate and temperature influence the crystal's thermal stability which is related to the solid–solid transition and fusion. The crystal size significantly increased when the nucleation and crystal growth took place at a slow rate.