Precipitation and Characterization of Chelerythrine Microparticles by the Supercritical Antisolvent Process

Chelerythrine was successfully micronized from methanol solution using Supercritical Carbon Dioxide (SC‐CO₂) as an antisolvent via the Solution Enhanced Dispersion by Supercritical Fluids through the Prefilming Atomization (SEDS‐PA) process. The morphology and particle size of the chelerythrine microparticles were visually analyzed by scanning electron microscopy (SEM). For the purpose of the optimizing operating conditions of the SEDS‐PA process, the influences of the experimental variables, i.e., temperature, pressure, solution flow rate and initial solution concentration, on the particle size and morphology of chelerythrine microparticles are discussed in detail. The results show that the best process conditions for the micronization of chelerythrine are: T = 313 K, P = 20 MPa, C = 2.0 g/L and F = 2.0 mL/min. The precipitates obtained under the optimized experimental conditions are short rod‐like chelerythrine microparticles with a mean particle size of 0.1–1 μm in width.     

Amoxicillin and Ethyl Cellulose Precipitation by Two Supercritical Antisolvent Processes

Composites of amoxicillin and ethyl cellulose in the micrometer range were precipitated by supercritical antisolvent (SAS) processes using carbon dioxide as antisolvent and a mixture of dichloromethane and dimethylsulfoxide as solvents. Morphologies and mean diameter ranges were analyzed by scanning electron microscopy. X‐ray photoelectron spectroscopy (XPS) and high‐performance liquid chromatography were carried out in order to ensure successful coprecipitation and to determine the amoxicillin contents in the final products. The SAS processes used differ mainly in the way in which the solutions are introduced: through a normal or a coaxial nozzle. The XPS results provided proof that amoxicillin was not distributed in the same way in all the samples. The release behavior of the composites obtained was evaluated in two biological fluids, i.e., simulated gastric and simulated intestinal fluids. The different systems led to the release of the drug in different ways; but in all cases slower solubilization was obtained than for the pure drug.     

Supercritical Antisolvent Particle Precipitation: In Situ Optical Investigations

The manner in which the presence of a solute can affect the mixing behavior of a solute, solvent and antisolvent in a supercritical antisolvent (SAS) micronization process is demonstrated. The mixing behavior was analyzed by applying a two‐dimensional (2D) Raman scattering technique. Mole fraction and partial density distributions were measured for the CO₂ antisolvent. The results originating from the optical investigations were correlated with the particle results. The experiments cover the variation of the solute concentration at fixed operating conditions of 10 MPa and 40 °C.     

Preparation of Emodin‐Polyethylene Glycol Composite Microparticles Using a Supercritical Antisolvent Process

Emodin‐polyethylene glycol (PEG) composite microparticles were obtained from a dichloromethane‐methanol mixture via the solution‐enhanced dispersion by supercritical fluids through prefilming atomization (SEDS‐PA) process. Morphologies, particle sizes (PSs), and emodin contents of the composite microparticles were analyzed by scanning electron microscopy and UV‐visible spectrophotometry. The crystallinity change of emodin before and after the SEDS‐PA process was demonstrated by X‐ray powder diffraction (XRD). The composite microparticles present nubbly, rod‐like emodin dispersed in PEG or a nubbly, sheet emodin inlay on PEG, with PSs ranging between 3 and 12 μm. The PSs of the composite microparticles increase with the increase of temperature, decrease with the increase of pressure, and do not seem to depend on the emodin content of the initial solute and on the solution flow rate. The emodin contents of the composite microparticles increase with the increasing emodin content in the initial solute and temperature and decrease with increasing solution flow rate.     

超临界CO2-GAS重结晶HMX过程温度对晶体形貌的影响

研究了以丙酮为溶剂的超临界 CO2 - GAS重结晶制细过程温度对 HMX晶型的影响 ,结果表明 :超临界 CO2 - GAS重结晶 HMX过程与常规的重结晶过程相似 ,温度对 HMX晶型起控制作用 ,而对颗粒尺寸影响不大 ;当局部操作温度大于 5 0℃时 ,结晶颗粒中会有α型 HMX生成 ;当整体温度大于 6 0℃时 ,产品中α型 HMX占主要部分。本文就 GAS重结晶过程温度对 HMX晶型影响的机理进行了探讨 ,认为流体压缩和结晶放热引起的局部过热是产生α型 HMX的主要原因     

Effect of Solvent on Nanoparticle Production of β‐Carotene by a Supercritical Antisolvent Process

Production of micro‐ to nano‐sized particles of β‐carotene was investigated by means of solution‐enhanced dispersion by supercritical fluids (SEDS). β‐Carotene was dissolved in dichloromethane (DCM), N,N‐dimethylformamide (DMF), n‐hexane, or ethyl acetate, and supercritical CO₂ served as an antisolvent. The effects of the organic solvents, operating pressure, and temperature were examined. The morphologies of the particles produced by the SEDS were observed by field emission‐scanning electron microscopy and particle sizes were determined by image analysis. Irregularly shaped microparticles were produced in the system with DCM and DMF solution. Plate‐like microparticles were generated by using n‐hexane solution and irregular nanoparticles by ethyl acetate solution. The optimum operating conditions were found to be ethyl acetate as solvent in a defined pressure and temperature range.     

Separation of tert‐Butyl Alcohol‐Water Mixtures by a Heterogeneous Azeotropic Batch Distillation Process

Tert‐butyl alcohol and water form an azeotrope at normal pressure. Simple distillation cannot be used to separate these two components. In this article, a systematic study of the separation of tert‐butyl alcohol–water mixtures with an entrainer by heterogeneous azeotropic batch distillation was performed. Based upon the thermodynamic behavior of the ternary mixtures, cyclohexane was chosen as the entrainer. It formed ternary and binary heterogeneous azeotropes with the original components. The process feasibility analysis was validated by using rigorous simulation with chemical process simulation software – HYSYS Plant 2.2 and DISTIL 4.1. Simulation results were then corroborated in a batch experimental column for the selected entrainer.     

Safety Study in a Supercritical Extraction Plant

This work presents a safety study of a supercritical extraction plant. In order to define process equipment and operation conditions, a supercritical fluid extraction (SFE) plant to produce 336 kg/d (60t/season¹⁾) sweet pepper oleoresin is presented. The plant was designed to operate at 40MPa extraction pressure, 40 °C extraction temperature, and 6MPa separation pressure using 10000Kg/h CO₂ as solvent. A formal analysis was carried out in order to identify the most important hazards. It is obvious that the dangers arising from this plant have much to do with the nature of the substances being processed, the way they are treated in the plant, and their tendency to take part in chemical reactions under these conditions. The basic procedure involved was first to identify the main types and sources of hazards (possibility of releases, fires, explosions, and operation of high‐pressure systems) and quantify the causes and effects. Standardized test methods were used for this. The work included representative tests such as Dow index and a detailed PROBIT analysis.     

Antisolvent micronization of BSA using supercritical mixtures carbon dioxide + organic solvent

In this work, expanded liquid antisolvent (ELAS) process has been used to micronize bovine serum albumin (BSA) solubilized in water. Carbon dioxide mixtures with ethanol, acetone or isopropyl alcohol, at expanded liquid conditions, have been used as the antisolvent. The effect of process parameters, such as the kind of co-antisolvent and the organic co-antisolvent/water/carbon dioxide mole fraction on the morphology and dimensions of the precipitates, was studied. Changing co-antisolvent and operating conditions, we obtained nanoparticles (with a mean diameter of about 60 nm ± 10 nm), sub-microparticles (with a mean diameter of 470 nm ± 130 nm), microparticles (with a mean diameter of 0.93 μm ± 0.37 μm) and expanded microparticles with an empty core (with a mean diameter of about 9 μm ± 5 μm). Fourier transform infrared analysis on BSA powders revealed that, using acetone as co-antisolvent, no modifications of the protein secondary structure were induced by ELAS processing.     

Novel Process Options for Application of Zeolites in Supercritical Fluids and Ionic Liquids

Supercritical fluids and ionic liquids offer attractive opportunities for modifying and applying zeolites as adsorbents and catalysts. After a brief introduction to the most important properties of these solvents, examples of zeolite applications in supercritical fluids and ionic liquids from the recent literature are discussed. Particular emphasis is put on the influence of reaction media on the processes occurring in the zeolitic pore systems, e.g., during shape‐selective conversions in zeolite catalysts. The present potential and future challenges for the application of zeolites in supercritical fluids and ionic liquids are identified. Most attractive process options arise from a combined use of both ionic liquids and supercritical fluids in integrated reaction schemes.     

超临界流体重结晶制备HMX微细颗粒和结晶速率的研究

Microparticle formation and crystallization rate of 1,3,5,7-tetranitro-l,3,5,7-tetraazacyclooctane (HMX) in acetone solution using supercritical carbon dioxide antisolvent (GAS) recrystallization were studied. Scanning electronic microscopy, X-ray diffraction and infrared radiation were used to examine particle size, crystallinity and chemical structure. The results show that β-HMX microparticle in different average size (2--9.5μm) and with narrow size distribution were obtained by controlling the expansibility, expansion speed, initial concentration and temperature during recrystallization of HMX. The formation of nuclei may be a main cause of consumption of solute when the solution is expanded rapidly enough and the equilibrium concentration is lower, in which almost monodisperse microparticle can be obtained.     

Batch foaming of chain extended PLA with supercritical CO2: Influence of the rheological properties and the process parameters on the cellular structure

This study has been dedicated to the foaming of modified poly (lactic acid) with supercritical CO₂. The first part of this work consisted in a rheological modification of neat PLA through chain extension. Improvement of the melt viscosity and elasticity has been achieved by the use of an epoxy additive during a reactive extrusion process. Rheological characterizations confirmed an increase of the melt strength due to this chain extension process. Foaming was then performed on the neat and modified PLAs using a batch process with supercritical CO₂ as blowing agent. The investigation of the foaming temperature revealed an enlarged processing window for modified PLAs compared to neat PLA. Depending on the foaming parameters, foams with a cellular structure ranging from macro scale to micro scale have been obtained. A concomitant effect of the CO₂-plasticization and the crystallisation on the melt rheology could explain this wide range of cellular morphologies.     

超临界流体萃取的溶媒和挟带剂

本文介绍了超临界萃取的原理，溶媒及挟带剂。     

The Potential of Surfactant Modified Supercritical Fluids for Dissolving Polar Dyes

The solubility of different polar dyes in supercritical carbon dioxide and ethane (scCO₂ and scC₂H₆), both modified and unmodified with various surfactants and solvents was determined at temperatures from 323–373 K and in pressure range from 10–45 MPa. The solubility data were correlated with some empirical equations. Furthermore, dyeing experiments with wool and cotton dyes were conducted in order to characterize the impact of modifiers on the dyeing procedure and coloring properties and to prove the practicability of modified fluid systems for commercial procedures.     

超临界溶剂中溶质的扩散系数关联

1引言扩散系数是重要的化工基础数据,由于测定较困难,它的预测就显得很重要。近几年这方面的研究热点之一是预测溶质在超临界溶剂中的扩散系数“－’‘。作者最近以roush－hard－sPhere扩散理论为基础,结合大量文献数据,提出了一种预测溶质在超临界溶剂中扩散系数的方法,其形式如下「‘’：用上述方法曾对107个溶质一溶剂系统（共1167数据点）的扩散系数作了预测,平均相对偏差约7．5％,精度较高［’‘。但它不适用于CO。一醒系统（现有的文献预测方法中均存在着这个问题）。此外,当溶质含卤原子较多时,误差也较大。本文的目的是…