Extraction of Natural Products Using Near-Critical Solvents

by M.B. King (Editor), T.R. Bott (Editor)

Overview

The aim of this book is to present the current state of the art of extracting natural products with near-critical solvents and to view the possibilities of further extensions of the technique. Relevant background theory is given but does not dominate the book. Carbon dioxide is the near-critical solvent used in most recent applications and inevitably receives prominence. In addition to general descriptions and reviews, the book contains three chapters by indus­ trial practitioners who describe in detail the operation of their processes and discuss the market for their products. Sections on the design of the pressure vessels and pumps required in these processes and on the acquisition of the data required for design are included. The costing of the processes is also discussed. There is good scope for combining a near-critical extraction step with other process steps in which the properties of near-critical solvents are utilised, for example as a reaction or crystallisation medium and a chapter is devoted to these important aspects. It is hoped that the work will be found to contain a great deal of specific information of use to those already familiar with this field. However the style of presentation and content is such that it will also be useful as an introduction. In particular it will be helpful to those wondering if this form of separation method has anything to offer for them, whether they are engineers, chemists or managers in industry, or in academic or research institutions.

Product Details

ISBN-13:	9789401049474
Publisher:	Springer Netherlands
Publication date:	11/02/2012
Edition description:	Softcover reprint of the original 1st ed. 1993
Pages:	325
Product dimensions:	6.10(w) x 9.25(h) x 0.03(d)

Table of Contents

1 Introduction.- 1.1 Compressed and liquefied gases as solvents: the commercial applications.- 1.2 The scope of the book.- 1.3 Range of solvent conditions regarded as ‘near-critical’.- 1.4 Range of available solvents.- 1.5 Range of components present in natural products: typical phase behaviour with near-critical carbon dioxide and similar near-critical solvents.- 1.6 Role of solvent density.- 1.7 Possible and actual process layouts.- 1.8 Advantages in use of near-critical solvents: future prospects.- Appendix: Some historical notes.- References.- 2 Food legislation and the scope for increased use of near-critical fluid extraction operations in the food, flavouring and pharmaceutical industries.- 2.1 Introduction.- 2.2 Solvent extraction of foodstuffs and flavourings: legal restrictions on solvents used and residual solvent levels.- 2.3 Widening the choice of extraction solvent: compressed and liquefied gases as solvents: economic and other problems in their use.- 2.4 Use of carbon dioxide for dense gas extractions: ‘rule of thumb’ solubility rules.- 2.5 Actual and proposed applications of extractions using dense CO2: tabular review of the literature.- References.- 3 Other uses for near-critical solvents: chemical reaction and recrystallisation in near-critical solvents.- 3.1 Chemical reaction in near-critical solvents.- 3.2 Recrystallisation in near-critical solvents.- References.- 4 Commercial scale extraction of alpha acids and hop oils with compressed CO2.- 4.1 Introduction, composition and brewing value of hops.- 4.2 Convenience of hop extracts.- 4.3 Advantages of compressed CO2 over conventional organic solvents for the extraction of hops: extraction plant using this solvent.- 4.4 Conclusions.- References.- 5 Commercial scale decaffeination of coffee andtea using supercritical CO2.- 5.1 Introduction: the extent of coffee and tea production worldwide and the need for decaffeination.- 5.2 Present-day demand for decaffeinated products and trends in the market.- 5.3 Brief description of the currently used processes for decaffeination and their history.- 5.4 Decaffeination with compressed CO2.- 5.5 The patent literature for decaffeination processes.- 5.6 Comparison of economic aspects of the CO2-based and ethylacetate-based decaffeination processes.- 5.7 Technical aspects of plant design.- 5.8 Conclusions.- References.- 6 Extraction of flavours and fragrances with compressed CO2.- 6.1 Introduction.- 6.2 The properties of CO2 as an extraction solvent.- 6.3 The raw materials.- 6.4 Equipment.- 6.5 Commercial use of CO2 extracts since 1982.- 6.6 Conclusions.- Appendix: CO2-extracted flavour and fragrance ingredients.- References.- 7 Physico-chemical data required for the design of near-critical fluid extraction process.- 7.1 The need for physico-chemical data.- 7.2 Phase equilibria.- 7.3 Mass transfer rate parameters.- Appendix: The fluid mass balance equations.- References.- 8 Design and operation of the pressure vessels used in near-critical extraction processes.- 8.1 Introduction.- 8.2 Classification of pressure vessels.- 8.3 Vessel design.- 8.4 Operation of the pressure vessels in a near-critical extraction plant.- 8.5 Design and development of equipment for the continuous extraction of solids.- References.- 9 Pumps and compressors for supercritical extraction.- 9.1 Introduction.- 9.2 Process requirements.- 9.3 Pumps for liquids.- 9.4 Compressors for gas recovery.- References.- 10 Estimation of separation cost.- 10.1 Introduction.- 10.2 Energy and economic assessment of near-critical extraction processes.- 10.3 Extractionwith a marginally subcritical solvent.- 10.4 Extraction with supercritical solvent.- 10.5 Energy and other costs in some typical cases.- 10.6 Example of preliminary costing.- References.