Some new frontiers in chemical engineering thermodynamics

Prausnitz, John M.

doi:10.1016/0378-3812(94)02636-f

Cited by 36 publications

(17 citation statements)

References 18 publications

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“…The quantitative description of a binary polymer/solvent equilibrium can be very hard to achieve in certain cases [21]. This statement holds particularly for the systems listed in Table 1, which are either glassy or ion-exchange polymers.…”

Section: Tentative Thermodynamic Interpretationmentioning

confidence: 96%

On Schroeder's paradox

Vallières

Winkelmann

Roizard

et al. 2006

Journal of Membrane Science

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Section: Tentative Thermodynamic Interpretationmentioning

confidence: 96%

On Schroeder's paradox

Vallières

Winkelmann

Roizard

et al. 2006

Journal of Membrane Science

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“…By focusing on only a few selected examples, they illustrate the wide range of applications for which thermodynamic analysis may be utilized: Aqueous two-phase systems (ATPS) (Chapter 8), biomolecule separation by liquid-liquid extraction using mixed solvents (Chapter 9), protein separation by salting out (Chapter 10) or by ion exchange chromatography (Chapter 11), and the use of hydrogels and their swelling behavior for many applications including drug delivery, drug formulation, applications in food and feed, consumer products, technical foams, superabsorbent materials, and many more (Chapter 6). It has been recognized for a long time that it is difficult to use classical models for excess Gibbs energies such as UNIFAC to predict the partition behavior of charged biomolecules [2,5]. Biomolecules often are polymers and most bear pH-dependent charges.…”

Section: Chaptersmentioning

confidence: 99%

“…This implies that design and optimization for these and even more complex processes have to follow the laborious and costly empirical route, rather than use of computer-aided flow sheeting programs for the evaluation of alternatives. This is an area where molecular thermodynamics can make a useful contribution [5,7].…”

Section: Chaptersmentioning

confidence: 99%

The Role Of Thermodynamics In Biochemical Engineering

2013

Thermodynamics in Biochemical Engineering

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This article is an adapted version of the introductory chapter of a book whose publication is imminent. It bears the title "BiothermodynamicsThe role of thermodynamics in biochemical engineering." The aim of the paper is to give a very short overview of the state of biothermodynamics in an engineering context as reflected in this book. Seen from this perspective, biothermodynamics may be subdivided according to the scale used to formalize the description of the biological system into three large areas: (i) biomolecular thermodynamics (most fundamental scale), (ii) thermodynamics of metabolism (intermediary scale), and (iii) whole-cell thermodynamics ("black-box" description of living entities). In each of these subareas, the main available theoretical approaches and the current and the potential applications are discussed. Biomolecular thermodynamics (i) is especially well developed and is obviously highly pertinent for the development of downstream processing. Its use ought to be encouraged as much as possible. The subarea of thermodynamics of live cells (iii), although scarcely applied in practice, is also expected to enhance bioprocess research and development, particularly in predicting culture performances, for understanding the driving forces for cellular growth, and in developing, monitoring, and controlling cellular cultures. Finally, there is no question that thermodynamic analysis of cellular metabolism (ii) is a promising tool for systems biology and for many other applications, but quite a large research effort is still needed before it may be put to practical use. IntroductionThermodynamics has had an enormous impact on a very wide variety of fields, including chemistry, biology, physics, geology, and in particular on applied engineering sciences such as chemical engineering [1]. Systematic application of chemical thermodynamics to process technology is one of the reasons why petrochemical plants can often be designed and petrochemical processes be developed with a bare minimum, if any, of experimental work.In biochemical engineering, the situation is radically different. The need for experimental trials is so overwhelming in bioprocess development that more often than not, extensive use is made of massively parallel experimentation involving such tools as microtiter plates, minireactors, robotic set-ups, and statistical experimental design. Therefore, the development of high-throughput systems and analytical equipment is now pursued at a very high pace. It can be speculated, however, that rigorous application of thermodynamics in biochemical engineering may be able to rationalize greatly bioprocess development and obviate a substantial fraction of this need for tedious experimental work [2].It was this vision that motivated a number of scientists about twenty years ago to organize an advanced course in thermodynamics for biochemical engineers to stimulate them to use thermodynamics more systematically in their work, and also to encourage further research in this area [2]. In the last 20 ye...

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“…The swelling is then driven by the repulsion between the fixed ionised functional groups of polymers until they are neutralised by hydration following Donnan equilibrium, i.e. electroneutrality in each phase and phase equilibrium for each mobile ion (Khare and Peppas, 1995;Prausnitz, 1995). Electrosteric stabilisation and complex coacervation are examples of industry applications in which polyelectrolytes play a major role.…”

Section: Sorption and Swellingmentioning

confidence: 99%

Useful Principles to Predict the Performance of Polymeric Flavour Delivery Systems

Benczédi

2010

Food Flavour Technology

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In this chapter, we review semi-empirical principles of chemical engineering that are particularly useful to understand the phase behaviour of glassy polymers applied to encapsulate flavours and fragrances. Hildebrand's solubility parameter is used to outline how the polarity of a polymer increases its cohesive energy density, its density, its glass transition temperature and how it reduces its permeability towards apolar molecules such as gaseous oxygen and most flavouring ingredients. Flory's model of polymer solutions is coupled to a generalised Freundlich adsorption model to highlight the limiting phase behaviour of polar polymer glasses at low partial pressures of water and of hydrogels at the saturation vapour pressure of water.This approach suggests that sigmoidal vapour sorption phenomenology is the macroscopic fingerprint of glassy materials. Below the glass transition point, water sorption is therefore assumed to take place on the pre-existing sites formed by an excess free volume, which characterises glassy polymers. This excess free volume needs typically to be minimised in controlled release applications to minimise the diffusion of oxygen and flavour molecules. Mass transport is further described with Fick's laws of diffusion to highlight the effects of polymer cross-linking or plasticisation, as induced by temperature or partial pressure of water. Diffusion-controlled kinetics, scaling with the square root of time, is distinguished from zero-order kinetics observed when mass transport is polymer relaxation-controlled. INTRODUCTIONThe encapsulation of flavours was initially motivated by the need to protect volatile food components from evaporation and oxidation by locking them in a solid carrier able to dissolve rapidly in water (Schultz et al., 1956). Nowadays, more emphasis is laid on slowing aqueous dissolution down and on triggered release systems activated typically by heat and mechanical stress. Controlled flavour release thus provides new solutions to the food industry and enables the development of innovative consumer goods. In this context, the primary objective of flavour delivery systems is to maximise flavour perception by generating impact and persistence when needed.Flavours are traditionally encapsulated by spray-drying an aqueous polymer solution, and the resulting glassy powders have a fine granulometry, favouring quick aqueous dissolution. The selective retention of flavour molecules as water evaporation proceeds during

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Some new frontiers in chemical engineering thermodynamics

Cited by 36 publications

References 18 publications

On Schroeder's paradox

On Schroeder's paradox

The Role Of Thermodynamics In Biochemical Engineering

Useful Principles to Predict the Performance of Polymeric Flavour Delivery Systems

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