Common Applications of Supercritical Fluid Extraction

Several organic compounds were added to modify the surface of ceria nanoparticles, and in-situ surface modification was confirmed by FT-IR and TGA analysis.

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and Adami, R., "Nanomaterials and Supercritical Fluids," J.

Synthesis of noble metallic nanoparticles, in general, and silver nanoparticles (SNPs), in particular, currently are of special interest. In the present paper, an overview of the enhanced properties of SNPs and consequential applications of SNPs are discussed. Common synthesis methods and their comparison with the microemulsion technology, particularly advantages of SNPs formation with microemulsion technology, are discussed. A brief overview of the basics of microemulsion technology for nanoparticles formation is also presented. The complete topical review of microemulsion synthesis technique used to date for the generation of SNPs is discussed comprehensively. Control parameters have been explicated for influencing size, size uniformity, and stability aspects of the SNPs reported in the literature, allowing a tailored synthesis for specific application. Recent modifications made on the synthesis of SNPs to obtain monodisperse, high yield and stability are also discussed. Lastly, some future trends and perspectives in these research areas are outlined.

Example 1. Synthesis of gallium oxide Ga2O3

In this review, we discuss the synthesis of functional nanoparticles using supercritical fluids, focusing on their unique characters. Enhanced transport properties, larger solubility, and easy operation in changing the phase behavior realize the instantaneous formation of solid products, leading to the synthesis of fine nanoparticles with narrow size distribution. Several methods are shown to prepare organic and inorganic nanoparticles using supercritical carbon dioxide or water. We then introduce our recent activities on the supercritical hydrothermal synthesis of metal oxide nanoparticles whose surface is modified with organic molecules. The organic molecules change the surface chemical character of the metal oxide nanoparticles, facilitating their handling and hybridization. We hope that this review provides a guide to the synthesis of various nanoparticles that are used as a key component for functional materials and future nanodevices.

involved in the use of supercritical fluids ..

Synthesis of many specialty chemicals involve use of organic solvents. Our objective in this project is to determine the feasibility of carrying out organic synthesis reactions in supercritical fluids. We propose to use supercritical fluids (SCFs), specifically supercritical carbon dioxide (SCCO2), as the reaction media. Although SCFs have seldom been explored for this purpose, they have properties that could make them nearly the ideal media for conducting organic synthesis reactions. SCFs are inert to most reactions, non-toxic, cheap, readily available, and environmentally acceptable. In addition, SCF densities can be varied over a wide margin by slight changes in temperature and/or pressure hence affecting reaction rate and selectivities by solubility and/or partial molar volume control.

Highly Efficient Organic Syntheses Using Supercritical Fluids

Carbon dioxide is the most widely used gas for supercritical fluid studies because of its moderate ...

Chemical Synthesis Using Supercritical Fluids…

A powerful capability of supercritical fluid extraction (SFE) is the ability to precisely control which component(s) of a complex matrix are extracted and which ones are left behind. This is accomplished through precise control of several key parameters including temperature, pressure, flow rate and processing time. It is possible to “tune” the fluid to extract those components of interest while leaving others behind. Additional advantages of SCFs are high extraction yields and superior product purity. Decomposition of materials almost never occurs due to the relatively mild processing temperatures. Carbon dioxide, which is the most commonly used SCF, has a critical temperature of 31°C and critical pressure of 73 atmospheres.

Since the organic molecules and metal salt ..

We are specifically interested in: (1) the replacement of organic solvents traditionally used in organic synthesis with environmentally benign supercritical fluids, (2) the control of product selectivity by adjustment of partial molar volumes by density, thereby decreasing and/or eliminating the formation of undesired by-products, (3) the removal of product from the reaction system through solubility control and hence affecting the equilibrium conversion and/or terminating the reaction at the desired extent, (4) affecting reaction selectivity by solubility control of the components involved, (5) obtaining a solvent free product after the reaction by expansion of the SCF.