Chemical Engineering Perspective Research Articles

Recent advances in molecular simulation: A chemical engineering perspective

AIChE JournalVolume 61, Issue 2 p. 370-383 Perspective: 2013 AIChE Institute Lecturer Award Recent advances in molecular simulation: A chemical engineering perspective Jeremy C. Palmer, Corresponding Author Jeremy C. Palmer Dept. of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204Correspondence concerning this article should be addressed to J. C. Palmer at [email protected] or P. G. Debenedetti at [email protected]Search for more papers by this authorPablo G. Debenedetti, Corresponding Author Pablo G. Debenedetti Dept. of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544Correspondence concerning this article should be addressed to J. C. Palmer at [email protected] or P. G. Debenedetti at [email protected]Search for more papers by this author Jeremy C. Palmer, Corresponding Author Jeremy C. Palmer Dept. of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204Correspondence concerning this article should be addressed to J. C. Palmer at [email protected] or P. G. Debenedetti at [email protected]Search for more papers by this authorPablo G. Debenedetti, Corresponding Author Pablo G. Debenedetti Dept. of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544Correspondence concerning this article should be addressed to J. C. Palmer at [email protected] or P. G. Debenedetti at [email protected]Search for more papers by this author First published: 15 December 2014 https://doi.org/10.1002/aic.14706Citations: 47Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume61, Issue2February 2015Pages 370-383 RelatedInformation

A novel fluorinated polymeric product for photoreversibly switchable hydrophobic surface

A new chemical product, that is, photoreversibly switchable hydrophobic surface coating, was synthesized by atom transfer radical polymerization and graft‐from method based on molecular design. Focusing on the strategy of new product development from the chemical product engineering perspective, the product characterization, switching mechanism analysis, performance evaluation, and model interpretation were carried out to confirm the new product manufacture and to ensure the product application with a following aging test. The results show that the product enables surfaces to have reversibly switchable wettability and excellent stability after a month‐long test with eight irradiation cycles. Additionally, the wetting behavior of silicon surface can be tuned between hydrophilicity and hydrophobicity based on blank sample using the surface engineering technique (decorated with functional film and surface roughening). The product presented here can be utilized for constructing a hydrophobic surface with photo‐induced controllable wettability in moisture‐resistance, and it also offers a new technique for the manipulation of liquids in microfluidic devices. © 2014 American Institute of Chemical Engineers AIChE J 60: 4211–4221, 2014

On the measurement of the real values of individual ionic activities: A chemical engineering perspective

This work demonstrates the perfect analogy between the standard method for determining activities in non-electrolyte mixtures and the method used for the determination of ionic activities in electrolyte solutions. For the case of electrolyte solutions, the general procedure of solving three equations with three unknowns is discussed and the reasons why this procedure failed to work for the case of KCl solutions are recapitulated. A modified iteration procedure implemented in this work gives convergence of the solution after three iterations. The crucial difference between eliminating the junction potential, by combination of independent equations, and the use of a proper estimate of its value is emphasized. A new model-free calibration procedure is proposed and sample calculations of K + and Cl − activities in KCl aqueous solutions are presented. Values of K + and Cl − activities in KCl aqueous solutions obtained by this new procedure and by a variety of other methods and researchers are compared.

Environmental challenges in the energy sector: a chemical engineering perspective

AbstractThe supply of energy in sufficient quantities and the access to clean water are among the most significant global challenges to address in the decades to come, as these are key elements of human well‐being and further development. These challenges are of course related, and future practices must consider their connectivity. As the present energy system is clearly reaching its limits in terms of sustainability, new approaches have been proposed based on much improved energy efficiency, development of renewable and new energy sources, and the use of carbon capture and storage for fossil resources. The industrial deployment of these alternate scenarios is intrinsically related to the availability of water on a large scale. Because the access to freshwater is becoming scarce in many countries, better water practices and the exploitation of new water resources must be developed for the supply of industrial water. This paper begins with a brief description of our present energy system based on fossil resources, this being a legacy of the industrial revolution. We then review the main drivers supporting the energy and water demand, and the constraints they are facing. The final section considers several chemical engineering challenges that arise when proposing ways of dealing with the energy‐environment nexus in the future. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Semiconductor nanowires: A chemical engineering perspective

Semiconductor nanowires: A chemical engineering perspective

Mineral Surfaces: A Mixed Blessing for the RNA World?

AstrobiologyVol. 9, No. 2 NEWS & VIEWSMineral Surfaces: A Mixed Blessing for the RNA World?Nicholas V. HudNicholas V. HudSearch for more papers by this authorPublished Online:16 Apr 2009https://doi.org/10.1089/ast.2008.0928AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byA Chemical Engineering Perspective on the Origins of Life5 May 2015 | Processes, Vol. 3, No. 2Abiotic synthesis of RNA in water: a common goal of prebiotic chemistry and bottom-up synthetic biologyCurrent Opinion in Chemical Biology, Vol. 22Enhanced Nonenzymatic Ligation of Homopurine Miniduplexes: Support for Greater Base Stacking in a Pre-RNA World6 December 2012 | ChemBioChem, Vol. 14, No. 1Mineral–organic interfacial processes: potential roles in the origins of lifeChemical Society Reviews, Vol. 41, No. 16 Volume 9Issue 2Mar 2009 Information© 2009 Mary Ann Liebert, Inc.To cite this article:Nicholas V. Hud.Mineral Surfaces: A Mixed Blessing for the RNA World?.Astrobiology.Mar 2009.253-255.http://doi.org/10.1089/ast.2008.0928Published in Volume: 9 Issue 2: April 16, 2009PDF download

A chemical engineering perspective of the gut

A chemical engineering perspective of the gut

Two experiments for the introductory chemical reaction engineering course

This paper describes a pair of chemical reaction experiments developed for Rowan University's introductory course in chemical reaction engineering: an esterification reaction carried out in a packed bed, and a competitive reaction in which the kinetics were influenced by micromixing. The first experiment is the esterification of ethanol and acetic acid to form ethyl acetate. Students first examine this reaction in their organic chemistry class. The experiment developed in this project re-examines this reaction from a chemical engineering perspective. For example, the reaction is reversible and equilibrium-limited, but in the organic chemistry lab, there is no examination of the kinetics. The complementary chemical engineering experiment examines the relationship between residence time and conversion. The second experiment is a competitive system involving two reactions: H 2BO 3 − + H + ↔ H 3BO 3 5I − + IO 3 − + 6H + → 3I 2 + 3H 2O The first reaction is essentially instantaneous. Thus, when H + is added as the limiting reagent, a perfectly mixed system would produce essentially no I 2. Production of a significant quantity of I 2 is attributed to a local excess of H +; a condition in which all H 2BO 3 − in a region is consumed and H + remains to react with I − and IO 3 −. In the spring of 2005, for the first time, both experiments were integrated into the undergraduate chemical reaction engineering course. This paper describes the use of the experiments in the classroom and compares the performance of the 2005 students to the 2004 cohort, for whom the course included no wet labs at all.

Process Simulation - From Large Computers and Small Solutions to Small Computers and Large Solutions

This paper reviews the evolution of process simulation in conjunction with the evolution of computer hardware and software technologies from a chemical engineering perspective. A brief history of this hardware evolution is presented and points to exponential growth of computing power. The current personal computers or full function workstations have at least 1GB of memory, 100GB hard drive and run at 4 GHz. We as chemical engineers can only benefit from this continued hardware evolution, as the personal computer has become our full function slide rule.Concurrent with this hardware evolution there has been a proliferation of operating systems and applications software. Some of the applications software has migrated from mainframes and minicomputers and some has been specifically written to take advantage of the user-friendly features available on today's personal computers. A review of this software is presented with particular emphasis on process simulation software. The currently available fifth generation, non-sequential interactive process simulator does make process modeling and design a truly rewarding experience. This software has been designed to allow the personal computer and the engineer to do what each does best, namely the personal computer performing the systematic number crunching and the engineer the intuitive aspect of process simulation and design. The paper will conclude with a look into the future development of process simulation and its interaction with chemical engineering practice.

Modelling counter-current chromatography: a chemical engineering perspective

In conventional chromatography, a solute is usually viewed to be longitudinally transported only in the mobile phase, remaining longitudinally motionless in the stationary phase. In counter-current chromatography, both phases undergo intense mixing in the variable force field of a coil planet centrifuge and longitudinal dispersion of matter in the stationary phase is not to be excluded. To take into account longitudinal mixing in both phases, a cell model of chromatographic process is proposed in which the number of perfectly mixed cells n is determined by the rates of mixing in stationary ( D S) and mobile ( D m) phases by the equation n= LF/(2A c D m ) (1+S f (λ−1)) with λ= K D D S/ D m ( F, L, A c and K D are the mobile phase flow-rate, column length, column cross-section and distribution ratio, respectively). This equation has been derived by comparing the discontinuous cell model with continuous diffusion assuming equilibrium conditions. Parameter determination and their relationships are discussed.

Bioreactors: a chemical engineering perspective

Despite breakthroughs in molecular biology that have opened up new synthesis routes to pharmaceuticals and fine chemicals, biotechnology has not been widely deployed for production of high volume, low cost chemicals. It is argued that the pace of development for large-scale bioprocesses can be accelerated by increasingly applying basic principles of chemical engineering together with front line concepts of molecular biology. A fundamental understanding of the coupling between kinetic, hydrodynamic, and transport processes in a bioreactor may also favorably impact process economics. The status and future opportunities in areas such as bioreaction kinetics, reactor selection, design, scale up and control are discussed. Several examples of how reaction engineering principles can lead to successful design and scale up and avoid common pitfalls are illustrated. Finally, the need to optimize the integrated process, rather than just the bioreactor, is indicated.

Novel opportunities for marine hyperthermophiles in emerging biotechnology and engineering industries

Despite the increased interest in hyperthermophiles and the rate of discovery of new species, their potential within the biotechnology industry has not been fully realized to date. The physiological characterization and biochemical survival mechanisms of marine hyperthermophilic Bacteria and Archaea are currently under investigation. However, very little information on their application in bioprocess systems is available. Since only a fraction of the world's oceans has been explored, the potential for isolating novel strains of marine hyperthermophiles is significant and hence they represent an, as yet, untapped biotechnological resource. Although much research has focused on the extraction of thermoactive enzymes, whole cell applications have been relatively overlooked. Running bioprocess systems using marine hyperthermophiles poses an interesting set of objectives, such as high temperature bioreactor operation and corrosion reduction of materials, for bioreactor design and manipulation of their products. Here, we discuss the biotechnological potential of marine hyperthermophiles from a biochemical engineering perspective and their use in ‘green chemistry’ applications. Both the bioprocess intensification implications and problems associated with cultivating these microbes in industrially relevant bioreactor systems are discussed from both a microbiological and chemical engineering perspective. © 2000 Society of Chemical Industry

Panel Discussion 2 How Much Control is Needed?

The question on how much control is needed is timeless and is always faced by process designers and operators at stages of process design or upgrading. This draws another set of equally important questions such as:. o Why to control. o Which controls to use. o Where to apply controls. o How to proceed with control system design and acquisition. These questions are best dealt with in light of:. o Present trends in the process industry. o Process operation requirements. The process industry is moving steadily toward:. o Fewer process steps. o Smaller inventory of materials. o Extensive heat integration. o Wider range of feedstocks, (not necessarily in Kuwait and other oil-producing countries). o Greater variations in demand. o More batch or semicontinuous operations. o More attention to effects on environment, safety, good and improved working conditions. These trends are in turn affected by the new trends in process control systems, which includes new control techniques and new instrumentation technology, which are known to provide:. o Higher production quality. o Reduced operating costs. o Improved overall system stability and safety. It was pointed out, however, that although approximately 95% of the control loops in a process environment are performing well with existing standard PID controllers, the remaining 5% can definitely benefit from the introduction of new control techniques. The need to use new controls will thus be primarily decided by such process operation requirements as:. o Nature and number of load disturbances to the process. o Possible variations in the characteristics of the process, e.g., dead time and gain variations. o Safety requirements. o Potential process constraints. o Final product specifications. To meet these requirements and constraints, process engineers have used some of the following tools:. o Manual control. o Feedback control. o Nonlinear feedback control. o Auto-select control. o Adaptive feedback. o Cascade control. o Ratio control (fixed and variable). o Feed forward control. o Decoupling controls. More recent control tools rely on such techniques as: as. o optimal control. o Adaptive techniques. o Multivariable control. o Robust control. These controls have a hierarchy represented by a pyramid in which the lowest level controls are at the base. The control hierarchy must be supplied by all the lower levels; for example, advanced feedback controls are impossible without good feedback loops, and plant optimization must have local optimization first. New technology provided wider flexibility in placing intermediate levels and in choosing when to place them. This was the case presented in the paper by watanabe (see Proceedings) when he chose to put feed forward controls into the digital computer (TDC-2000 and IBM ACS), implementation of controls in the higher levels of the pyramid requires more knowledge about the process to be controlled from a chemical engineering perspective. One factor that affects the implementation of controls in general is the availability of adequate sensors, but, as pointed out, sensor technology is lagging behind control technology. Innovative ideas are appearing in modern measurement techniques, such as using gas chromotographs for closing control loops, an idea that was totally out of the question only few years ago.