超临界流体技术在含能材料中的应用进展

综述了超临界流体技术在含能材料细化、表面包覆以及萃取和回收领域的应用现状.阐述和分析了超临界流体溶液快速膨胀结晶法、超临界气体反溶剂结晶法和超临界流体萃取技术在上述过程中的作用原理,并对各个方法所达到的效果进行了述评.指出了今后研究工作中应注意的一些问题和研究重点.     

超临界流体改性高分子聚合物研究进展

超临界流体因兼具液体和气体特性而倍受关注。主要介绍二氧化碳、甲醇、水等超临界流体在高分子聚合物改性、废旧塑料/橡胶回收、纤维素水解及其他方面的应用,并展望了超临界流体在高分子材料领域的应用前景。     

超临界流体沉析制备微细颗粒的技术及其应用

快速膨胀超临界流体溶液（ＲＥＳＳ）过程和以超临界流体为稀释膨胀剂（ＧＡＳ）过程是制备微细颗粒的新技术。本文着重分析了用ＲＥＳＳ和ＧＡＳ过程制备微细颗粒的特点及影响因素，介绍了在高分子聚合物、无机盐、陶瓷材料、有机物、药物及含能材料方面的应用，提出超临界流体沉淀技术将成为制备特殊细颗粒材料、超薄膜及提纯热敏性、易氧化物质的有效手段。     

Formation of Particles of Explosives with Supercritical Fluids

The particle properties of components of explosives and propellants, i.e. the particle size, the particle size distribution and the particle shape, are very important. Especially with regard to insensitive explosives, the formation of crystals without spots, i.e. free of solvent inclusions, is aspired. New processes, taking advantage of the special characteristics of high-compressed respectively supercritical fluids, offer many possibilities to influence the properties of solid particles. For the RESS process (Rapid Expansion of Supercritical Solutions), the formation of particles results from the rapid expansion of a loaded supercritical fluid. The GAS process (Gas Anti-Solvent) uses a high-compressed fluid as anti-solvent to lower the solvent power of a common solvent and thus to recrystallize the solid. In this report, the different processes to form particles of explosives and propellants with supercritical fluids are explained, and the first results are presented.     

Removal of Pollutants from Solid Matrices Using Supercritical Fluids

Abstract

Several supercritical fluid extraction (SCFE) processes have been proposed for removing toxic and intractable organic compounds from a range of contaminated solids. These include soil remediation and the regeneration of adsorbents used to treat wastewater streams such as granular activated carbon (GAC). As a separation technique for environmental control, SCFE has several distinct advantages over conventional liquid extraction methods and incineration. Most notably, the contaminant is removed from the solvent in a concentrated form via a change in pressure or temperature and can be completely separated upon expansion to atmospheric pressure.

The viability of SCFE hinges on process conditions such as solvent-feed ratio and solvent recycle ratio. The necessity of recycling solvent complicates the contaminant separation step since a complete reduction to atmospheric pressure would create large recompression costs. Because of this, the pressure and temperature dependence of contaminant solubility must be understood so that operating conditions for the separation step can be defined. Fortunately, this is the most developed aspect of SCF technology. However. the mass transfer limitations to removing contaminants from solids change with solvent flow rate.

This paper discusses the use of SCFE for environmental control and presents results for the removal of DDT and 2-chlorophenol from GAC. 2-chlorophenol is almost completely removed with pure CO₂ at 40°C and 101 bar while only 55% of the DDT is removed at 40°C and 200 bar. These differences in regeneration efficiency cannot be understood solely in terms of solubility but point to a need for detailed studies of adsorption equilibrium and mass transfer resistances in supercritical fluid systems.     

Prediction of the Strength of Energetic Materials Using the Condensed and Gas Phase Heats of Formation

The strength of energetic materials is one of the principal parameters to express their performance. Two new methods were introduced for the prediction of the strength of C_aH_bN_cO_d energetic materials through the Trauzl test. They are based on elemental composition and the condensed or gas phase heats of formation of energetic compounds. The model is based on the gas phase heat of formation, uses the group additivity method and requires only the molecular structure of the desired energetic compound. These methods provide more reliable predictions as compared to the best available theoretical methods. Some of the benefits of these new models are their accuracy, precision, simplicity, and low price.     

The Possibility of Reprocessing of Spent Nuclear Fuel Using Supercritical Fluids

For the first time, the possibility of dissolution of spent nuclear fuel from a nuclear power plant in liquid and supercritical carbon dioxide was demonstrated. As shown by the example of spent nuclear fuel, the dissolution and the extraction of actinides and fission products by solutions of tributyl phosphate and nitric acid adducts TBP(HNO₃)_1.8 in carbon dioxide can be used as one of the stages of spent nuclear fuel reprocessing.     

Stripping Organics from Metal and Mineral Surfaces Using Supercritical Fluids

Abstract

Superalloy grinding swarf was treated with supercritical CO₂ alone, and with various modifiers. Experiments were conducted in a downflow batch mode at pressures of 0 to 5,000 psig, temperatures of 20° to 250° C, and times of 15 to 24O min using up to 25 g of solvent per gram of swarf. Organic dissolution increased with pressure almost linearly to 5,000 psig. Temperature affected dissolution slightly at lower pressure, but not significantly at higher pressure. Certain alcohols used as modifiers dramatically improved organic dissolution. The solvent, modifier, organics, and solids were easily recovered as separate products.     

超临界流体技术在分离工程领域中的应用

文章阐述了超临界流体分离技术的原理、流程与特点.综述了该技术在分离工程领域的应用方向、存在的问题及未来的发展前景.指出了该技术兼具精馏和萃取两种分离作用效果,在天然资源成份的分离提取、脱除有害成份或杂质、清洗、色谱分析等诸多领域部有着其独特的开发应用优势.     

超声强化超临界流体萃取机理的研究

从实验和理论上对超声强化超临界流体萃取的机理进行了研究。采用自行设计的内插式超声强化超临界流体萃取装置,运用数码显微成像系统和透射电镜观察了有、无超声作用下超临界流体萃取中空化测试材料和海藻细胞微观结构的前后变化,分析了超声对超临界流体萃取海藻中二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）的传质和萃取率的影响,并根据声化学原理对超临界流体中附加超声场时能否产生空化现象进行了探讨。实验结果发现超声对超临界二氧化碳流体中的空化材料和海藻细胞壁不产生破坏作用,不会产生声空化效应,但提高了海藻中EPA和DHA的萃取传质效果。其实验结果与理论推导相一致。结果表明：超声强化超临界流体萃取的机理不是源于超声空化,而是超声在微环境内产生的机械波动效应和热效应。     

环境友好的超临界流体技术在化工环保领域中的应用

介绍了近几年来超临界流体技术在超微粒子的制备、复相催化反应以及环境保护中的应用。     

含能材料的细观损伤

综述了含能材料损伤的研究现状,介绍了损伤的产生、实验模拟及其表征,损伤对含能材料的撞击感度、燃烧及爆轰性能的影响以及损伤本构关系,并进行了相应的评述。对今后需要开展的工作进行了展望。