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Continuous crystallization of adipic acid with ultrasound 总被引:1,自引:0,他引:1
The application of a novel continuous cooling crystallization system coupled with ultrasound technology to crystallize adipic acid from an aqueous solution was investigated. Both continuous ultrasound irradiation and silent (control) regimes were used in order to elucidate the effects of unstable cavitation on the duration of the transient period, steady state operating conditions, crystal habit, and particle size distribution.The results reveal that under continuous ultrasonic irradiation the steady state particle size distribution is achieved after shorter times, with a consistent reduction of the steady state supersaturation resulting in increased product yields relative to silent continuous crystallization experiments. Continuous crystallization with ultrasonic irradiation results in significantly smaller crystal sizes, reduced agglomeration and an improved habit of crystals. Furthermore, the influence of mean residence time using continuous ultrasound produces a smaller change in particle size and size distribution. Finally, the experiments reveal a noticeable reduction of the fouling on non-cooling surfaces and underline the need for intermittent discharge to prevent classification on withdrawal product. 相似文献
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In this study, the impact of agitated drying on the physical and bulk powder properties of an active pharmaceutical ingredient (API) is presented. The effects of different agitated drying conditions such as agitation rate, drying temperature, drying time pre-agitation, drying time during agitation and number of solvent wash cycles on the bulk density, millability, flow and specific surface area is reported. The crystal morphology is altered from fibrous needles to agglomerates when switching from tray to agitated drying. An increase in bulk density and specific surface area was evident when using agitated drying compared to tray drying as hard coarse granules were produced with an increase in the number of fine particles < 10 μm. The bulk density was found to increase with an increase in agitation speed, drying time and number of solvent wash cycles used during filtration. Controlling both fine and coarse particle size of the granules for this API during agitated drying was difficult to achieve due to the fibrous crystal habit. However, the increase in the bulk density observed has the potential to facilitate improvements in the ease of drug product development. In the case of this system further particle size control was required through the use of dry milling. 相似文献
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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. 相似文献
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H. Liu C. G. Biliaderis R. Przybylski N. A. M. Eskin 《Journal of the American Oil Chemists' Society》1994,71(4):409-415
The effects of various factors on sediment formation in canola oil were studied. The crystallization temperature of sediment
varied with cooling rate, whereas the melting temperature depended on heating rate as well as the cooling rate during sediment
formation. The final crystal size depended on cooling rate. The crystal habit of sediment was generally rod-like but could
change to a round and leaf-like shape at low cooling rates (<0.5°C/min). Crystal nucleation occurred in the initial stage
of crystallization, while crystal growth was observed during the whole crystallization process, decreasing as cooling proceeded.
Crystal growth rate of the sediment was proportional to the crystal surface area Lecithin did not affect the phase transition
temperatures of sediment, but retarded crystal growth. 相似文献
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Wen J. Liu Cai Y. Ma Jing J. Liu Yang Zhang Xue Z. Wang 《American Institute of Chemical Engineers》2017,63(3):967-974
For reactive crystallization of pharmaceuticals that show a rapid reaction rate, low solubility of active pharmaceutical ingredient and hence a large supersaturation, it was found in a recent study that a process design which integrates an impinging jet mixer and batch stirred tank produces high quality crystals. The current investigation examines if the short processing time of reactive crystallization permits the impinging jet mixer—stirred tank design to be modified to operate in a continuous mode. The new design combines an impinging jet mixer for feed introduction and reaction with a continuous stirred tank reactor (CSTR) and tubular reactor for crystal growth. A study of reactive crystallization of sodium cefuroxime (an antibiotic), using first a 1L CSTR then scaling to a 50L CSTR, found that the new design produces crystals of higher crystallinity, narrower particle size, and improved product stability, than batch crystallizers. © 2016 American Institute of Chemical Engineers AIChE J, 63: 967–974, 2017 相似文献
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结晶过程是化工单元操作中一种高效节能的固液分离与提纯技术,广泛应用于食品、医药、染料等生产过程。结合超声法、图像法和光学浊度法研究了无水醋酸钠的结晶过程,通过超声模型结合最优正则化反演算法求解晶体颗粒粒度分布,在线测量了不同降温速率和搅拌速率下的析晶温度、晶体尺寸和形貌变化。结果表明:较快的降温速率可促进晶体生长,搅拌速率较快初期晶体尺寸较大,但后期由于颗粒磨损致平均尺寸减小;相同条件下光学浊度法较超声法较早测得析出晶体,实验中析晶温度偏差低于15%;图像法直观观察到了晶体生长过程并较好表征了晶粒形貌,与超声法具有接近的晶粒增长趋势,当晶体稳定析出后两者体积中位径偏差在15%以内,均较好地反映了实验条件对结晶晶体尺寸的影响。光学方法可更精细体现结晶初期特征,而在结晶后期超声法仍可对粒径进行有效测量。 相似文献
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相比于传统的溶液相结晶,凝胶用作结晶介质时,由于能抑制对流和减慢溶质分子的扩散,除了能提供较大的过饱和度且不会导致爆发成核,以及使溶质分子在生长面上连续地生长之外,还可以通过设计特定的凝胶剂为溶质分子提供模板或者活性成核位点,这使得凝胶相结晶成为了一种有效的结晶控制手段,引起了研究人员的广泛关注。综述了高分子凝胶、超分子凝胶以及无机凝胶如何有效地控制结晶成核和生长的速度,调控晶型、晶习和晶体粒度,简单介绍了微凝胶在溶液相结晶中的作用,以及凝胶相结晶未来的发展趋势。 相似文献
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采用平衡法研究了七水硫酸亚铁在黑钛液中的溶解度,通过拟合得到了其溶解度方程,并利用FBRM在线监测溶液结晶情况,测量了其结晶介稳区.通过间歇动态法研究了七水硫酸亚铁的结晶动力学,采用矩量变化法求解了粒数衡算方程,并利用最小二乘法对动力学实验数据进行多元线性回归后得到七水硫酸亚铁成核速率和生长速率方程,结果表明:搅拌速率和降温速率对七水硫酸亚铁结晶过程影响显著,因此,针对搅拌速率和降温速率对结晶工艺的影响进行了分析,并对优化前后七水硫酸亚铁产品进行了对比,发现优化后晶体呈规则的棱形,产品粒度明显增大,小颗粒晶体显著减小. 相似文献
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《分离科学与技术》2012,47(10):1402-1410
Antisolvent crystallization was performed to precipitate roxithromycin particles from organic solutions. Roxithromycin was dissolved in acetone at different concentrations and each solution was injected into an aqueous antisolvent leading to prompt particle formation. The effects of various experimental variables (solution injection rate, solution concentration, and temperature) on the particle size of roxithromycin were investigated. In addition to these variables, the effect of ultrasound on the resulting particle size was investigated by changing process parameters such as wave intensity (power output), sonication time, and the moment of ultrasonic application. When the drug solution was rapidly injected into the antisolvent, smaller crystals were obtained. Smaller crystals were obtained when solutions with high drug concentrations were used and also when the crystallization took place at lower temperatures. The particle size decreased with the increasing power output of ultrasound and with the increasing sonication time. It was also found that the ultrasonic wave induced the reduction of the particle size only when the ultrasound was applied to the solution at the initial stage of crystallization. 相似文献
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With the aim of simulating the product crystal size, which is one of the important physical properties for active pharmaceutical ingredients, an antisolvent crystallization model is proposed, including only six experimentally determined kinetic parameters to develop a concise model. As a first step, the methodology to assess the growth rate parameters, which are some of the six kinetic parameters, is discussed. An approach for appropriately treating the size distribution data obtained by means of the laser diffraction/scattering method is suggested. The determined growth rate parameters could be used to simulate the crystal size indicating that the simulation by crystallization modeling is a practical application for the pharmaceutical industry. 相似文献
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结晶法是工业上生产对二甲苯的主要方法之一。现有对二甲苯结晶动力学参数均单纯由结晶母液的温度和浓度变化通过非线性优化法而获得,未检测对二甲苯的晶体粒度数据,因而其准确性难以得到保证。本文利用超声在线粒度仪(OPUS)检测对二甲苯晶体的粒度分布,通过添加晶种的间歇悬浮熔融结晶实验,应用矩量变换法测定82%(质量)对二甲苯-间二甲苯体系中的对二甲苯结晶动力学。利用最小二乘法对动力学实验数据进行多元线性回归后得到了对二甲苯结晶动力学方程,研究结果表明,在对二甲苯悬浮熔融结晶过程中,溶液相对过饱和度对对二甲苯晶体成核速率的影响大于对晶体生长速率的影响,搅拌速率对成核过程影响明显,而晶浆悬浮密度对成核速率的影响不大。 相似文献
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采用聚焦光束反射测量技术(FBRM)考察了氯化钾(KCl)间歇冷却结晶过程中晶体成核和生长规律,重点研究了降温速率对KCl水溶液冷却时产生过饱和度的影响,以及添加晶种的相关条件(如晶种粒径和添加量等因素)与KCl晶体产品粒度的关系。同时,采用直接冷却刺激起晶产生“晶种”,并控制其生长达到控制晶体产品粒度的目的。结果表明,在添加晶种条件下,程序降温过程产生的低过饱和度不易引起爆发成核,且晶种的添加量决定着晶体产品的平均粒度与理想生长模型的偏差。另外,降温速率是冷却刺激起晶产生“晶种”粒径的关键因素。 相似文献
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针对头孢他啶结晶产品聚结、晶习差、粒度分布不均匀等问题,设计了双股进料结晶工艺,并将结晶环境控制在介稳区,有效避免自发成核,操作简单,容易控制。采用单因素法研究了结晶液初始浓度、料液流加速率、搅拌速率、温度以及养晶时间对结晶产品收率、晶习及粒度分布的影响,确定了优化的工艺参数:结晶液初始浓度(溶质质量/溶剂质量) 0.33 g·g-1,料液流加速率0.14 mL·min-1,温度27℃,养晶时间60 min,搅拌速率为250 r·min-1可以得到均匀的片状头孢他啶晶体,晶习完整,中值粒径达到184μm,径距为1.290,收率可以达到80%。 相似文献
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晶体的颗粒尺寸分布和形状是结晶产品的两个关键质量指标,不仅影响结晶产品的性质,还影响下游的过滤、干燥及运输存储等过程。利用超声粒度分析仪、衰减全反射傅里叶红外光谱仪、浊度仪与二维成像系统等分析仪器在线测量了不同搅拌速率和不同降温速率下阿司匹林乙醇溶液结晶过程中温度、浓度、颗粒尺寸分布和形状的变化情况。实验结果表明:较低的降温速率或者较大的搅拌速率条件下得到含有大量细晶的阿司匹林结晶产品;较高的降温速率下得到长宽比较大的阿司匹林结晶产品。调节降温速率和搅拌速率是一种有效控制阿司匹林结晶产品尺寸分布与形状的方法。 相似文献
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通过实验筛选得到适合果糖结晶的混合溶剂,利用中通量结晶仪器Crystalline测定了果糖在水-乙醇(水的摩尔分数为0.39)混合溶剂中的溶解度和介稳区,采用Apelblat方程拟合了溶解度数据。基于热力学数据设计了晶种引晶的果糖冷却结晶工艺,过程优化得到的产品收率可达78.2%以上,纯度可达99%以上,晶体形貌规则,表面光滑,粒度分布窄。当晶体粒径大于100 μm时,利用粒度无关生长的粒数衡算方程建立了果糖连续结晶过程的动力学模型,模型表明晶体生长级数大于成核级数。 相似文献
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This work investigates the use of ultrasonication for the dilution crystallization of naproxen. Naproxen solution was prepared in acetone, while water was used as the anti-solvent. The main objective of this study was to determine the effect of sonication on the thermodynamic properties (solubility, metastable zone width, and induction time) and particle size of naproxen crystals. The use of sonication was compared to conventional stirred crystallization methods. When the solvent ratio (Vacetone/Vwater) is low, no significant difference exists between the naproxen solubility in either the sonicated or stirred solutions. However, at higher solvent ratios (Va/Vw = 9) and at low temperatures (0°C), ultrasonication increases the solubility of naproxen from 0.171 to 0.193 g/mL. Compared to conventional stirred crystallization techniques (the metastable zone width is 0.024 g/mL), ultrasonic crystallization is characterized by a narrower metastable zone (the width is 0.010 g/mL), and with ultrasonic crystallization the induction time decreases by about 50 seconds. During ultrasonic crystallization, the average naproxen particle size is reduced from 22.6 to 10.5 μm by increasing the power and time of ultrasonication. Particle sizes and crystal morphologies obtained using ultrasonication were significantly improved compared to those produced with stirring. 相似文献