Download or read book Fundamental Studies on the Enzymatic Liquefaction and Rheology of Cellulosic Biomass Via Magnetic Resonance Imaging Velocimetry written by Maria Jose Cardona and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Worldwide need for alternatives to fossil fuels has driven significant research effort toward the development and scale-up of sustainable forms of energy. Second-generation biofuels, obtained from the breakdown of lignocellulosic biomass (e.g., agricultural residues), present a promising alternative. In biofuel production, the enzymatic hydrolysis of cellulose to glucose is currently one of the most expensive steps in the biochemical breakdown of lignocellulosic biomass. Economic considerations for large-scale implementation of this process demand operation at high solids loadings of biomass (>15\% (w/w)) due to potential for higher product concentrations and reduction of water usage throughout the biorefining process. In the high-solids regime, however, biomass slurries form a high viscosity, non-Newtonian slurry that introduces processing challenges, especially during the initial stages of hydrolysis (liquefaction), due to the low availability of water in the bulk phase. Furthermore, a concomitant reduction in glucose yields with increase in solids loadings has been observed, a phenomenon that is not well understood, but if overcome could hold the key to achieving desirable yields during hydrolysis. In order to better understand liquefaction, a magnetic resonance imaging (MRI) rheometer was used to perform in-line, in situ, real-time, and noninvasive studies on biomass slurries undergoing enzymatic hydrolysis. Batch and fed-batch experiments were done on lignocellulosic and cellulosic substrates with both purified and mixtures of enzymes, under various reaction conditions. The mechanism of liquefaction was found to be decoupled from the mechanism of saccharification. In addition, end product inhibition was found to have an impact on both saccharification and liquefaction during the initial stage of hydrolysis, which has an impact on scale-up of hydrolysis processes. Lastly, to address and overcome high-solids limitations, a fed-batch liquefaction process based on using real-time slurry yield stress as a process control variable was designed and tested with a delignified cellulosic substrate. The timing of enzyme addition relative to biomass addition influenced process efficiency, and the upper limit of solids loading was ultimately limited by end product inhibition. The impact of these findings on process kinetic modeling and scale-up are also discussed.
Download or read book Transport Phenomena and Rheology of Cellulosic Fiber Suspensions written by David Michael Lavenson and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Enzymatic conversion of lignocellulosic substrates is an important step in the biorefining process for the production of fuels and chemicals. Industrial implementation of cellulosic ethanol processes has been hindered by the lack of an economic and efficient way of digesting the cellulosic biomass feedstock. In order to reduce unit operations costs in the areas of mixing, handling, pumping, and separations, mass solids contents of the feed biomass must exceed approximately 20%. Above approximately 10% solids concentrations, cellulosic suspensions behave as non-Newtonian slurries while most of the moisture is retained within the substrate walls, making mixing and homogenization challenging. The underlying transport phenomena that govern these suspensions are complex and not completely understood. In this work, mass transfer and rheological behavior of high solids cellulose substrates are investigated. These studies use magnetic resonance imaging (MRI) to measure: 1. diffusion and adsorption in cellulosic fiber beds using labeled paramagnetic tracers; 2. velocity flow profiles of suspensions in tube flow to obtain pertinent rheological parameters; and 3. effects of mixing on the rates of liquefaction and saccharification in highly concentrated cellulose suspensions. MRI is a non-invasive technique which has been used for flow-imaging, diffusion, and adsorption studies. It is highly advantageous for the opaque biomass system which cannot be examined using light microscopy or other optical methods. Other techniques are used to probe the effects of fiber properties on diffusion-adsorption, liquefaction, and saccharification. Diffusion coefficients for MnCl2 and Gd-BSA are reported for various cellulosic suspensions, including delignified cellulose and dilute-acid pretreated lignocellulosic biomass. Diffusion is found to be highly dependent on the rate of adsorption in the fiber beds. The adsorption behavior of BSA on various cellulosic substrates, both lignocellulosic and delignified, is also investigated. Biomass suspension yield stress values are measured using MRI, and the resolution and uncertainty of the MRI technique are compared quantitatively with literature data collected from conventional rheometers. The MRI technique compares well with conventional techniques and offers improvements in sampling size, sampling error, measurement time, and uncertainty. Lastly, rates of liquefaction and extent of saccharification are measured for high solids content fiber suspensions undergoing enzymatic hydrolysis. A significant difference in the rates of liquefaction and saccharification is attributed to initial homogenization of enzyme, indicating the benefits of mixing enzyme and substrate on the centimeter scale. Application of these results to future work and industrial implications is also discussed.
Download or read book Studies of Rheological and Mixing Properties of Multi component Systems Using Magnetic Resonance Imaging written by Youngsoo Lee and published by . This book was released on 2001 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Study of Structural Features Affecting Enzymatic Hydrolysis of Lignocellulosic Biomass written by Li Zhu and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lignocellulose is a promising and valuable alternative energy source. Native lignocellulosic biomass has limited accessibility to cellulase enzyme due to structural features; therefore, pretreatment is an essential prerequisite to make biomass accessible and reactive by altering its structural features. The effects of substrate concentration, addition of cellobiase, enzyme loading, and structural features on biomass digestibility were explored. The addition of supplemental cellobiase to the enzyme complex greatly increased the initial rate and ultimate extent of biomass hydrolysis by converting the strong inhibitor, cellobiose, to glucose. A low substrate concentration (10 g/L) was employed to prevent end-product inhibition by cellobiose and glucose. The rate and extent of biomass hydrolysis significantly depend on enzyme loading and structural features resulting from pretreatment, thus the hydrolysis and pretreatment processes are intimately coupled because of structural features. Model lignocelluloses with various structural features were hydrolyzed with a variety of cellulase loadings for 1, 6, and 72 h. Glucan, xylan, and total sugar conversions at 1, 6, and 72 h were linearly proportional to the logarithm of cellulase loadings from approximately 10% to 90% conversion, indicating that the simplified HCH-1 model is valid for predicting lignocellulose digestibility. Carbohydrate conversions at a given time versus the natural logarithm of cellulase loadings were plotted to obtain the slopes and intercepts which were correlated to structural features (lignin content, acetyl content, cellulose crystallinity, and carbohydrate content) by both parametric and nonparametric regression models. The predictive ability of the models was evaluated by a variety of biomass (corn stover, bagasse, and rice straw) treated with lime, dilute acid, ammonia fiber explosion (AFEX), and aqueous ammonia. The measured slopes, intercepts, and carbohydrate conversions at 1, 6, and 72 h were compared to the values predicted by the parametric and nonparametric models. The smaller mean square error (MSE) in the parametric models indicates more satisfactorily predictive ability than the nonparametric models. The agreement between the measured and predicted values shows that lignin content, acetyl content, and cellulose crystallinity are key factors that determine biomass digestibility, and that biomass digestibility can be predicted over a wide range of cellulase loadings using the simplified HCH-1 model.
Download or read book Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks written by Massachusetts Institute of Technology. Department of Nutrition and Food Science and published by . This book was released on 1978 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enzymatic Hydrolysis of Cellulose written by and published by . This book was released on 1991 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies in the Liquefaction of Biomass written by Wayne B. Severn and published by . This book was released on 1987 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Study on Kinetics and Transport Phenomena in Low Water Dilute Acid Total Hydrolysis of Cellulosic Biomass written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this research is to delineate the process of the dilute-acid hydrolysis of biomass and seek better understanding of the reactions involving dilute-acid treatment of lignocellulosic biomass. Specifically the scope of the work entails the following two primary technical elements: Verification of the heterogeneous nature of the reaction mechanism in dilute-acid hydrolysis of cellulosic component of the biomass. Experimental investigation to identify the overall reaction pattern and the kinetic constants associated with dilute-acid hydrolysis of the cellulosic component of the agricultural residues.
Download or read book Developing a Fundamental Understanding of Biomass Structural Features Responsible for Enzymatic Digestibility written by Jonathan O'Dwyer and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rheometry of Pastes Suspensions and Granular Materials written by Philippe Coussot and published by John Wiley & Sons. This book was released on 2005-06-14 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive examination of rheometry theory and its practical applications This publication enables readers to understand and characterize the flow properties of complex fluids and, with this knowledge, develop a wide range of industrial and consumer products. The author fills a gap in the current literature by presenting a comprehensive description of the rheological behavior of pastes, suspensions, and granular materials and by offering readers the rheometrical techniques needed to effectively characterize these materials. With his extensive experience in both academic and industrial research, the author is able to take the field to a new level in: * General schematic classification of the behavior of pastes,suspensions, and granular materials * Systematic review, analysis, and quantification of experimental problems with complex fluids * Insight into the flow behavior of complex fluids gained through the most recent discoveries and research techniques * Comprehensive rheometrical analysis of data obtained from research across a broad range of industries In addition to gaining a thorough understanding of the theory underlining rheometry, readers discover its many practical applications. Throughout the publication, specific examples are provided that illustrate how theory is applied, including examples involving food, civil engineering, cosmetics, pharmaceuticals, paper coatings, paint and ink, ceramics, sewage sludges, granular materials, and natural materials. In summary, this publication provides a comprehensive review of the behavior of pastes, suspensions, and granular materials as well as detailed analysis of rheometrical techniques. Everything needed to determine the behavior and movement of complex fluids is provided. It is, therefore, a recommended resource for rheologists, engineers, and researchers, as well as students who deal with complex fluids in product formulation, quality and process control, and process plant design.
Download or read book Foams and Emulsions written by J.F. Sadoc and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: A general and introductory survey of foams, emulsions and cellular materials. Foams and emulsions are illustrations of some fundamental concepts in statistical thermodynamics, rheology, elasticity and the physics and chemistry of divided media and interfaces. They also give rise to some of the most beautiful geometrical shapes and tilings, ordered or disordered. The chapters are grouped into sections having fairly loose boundaries. Each chapter is intelligible alone, but cross referencing means that the few concepts that may not be familiar to the reader can be found in other chapters in the book. Audience: Research students, researchers and teachers in physics, physical chemistry, materials science, mechanical engineering and geometry.
Download or read book Program and abstracts book written by and published by . This book was released on 2001 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bubbly Flows written by Martin Sommerfeld and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.
Download or read book Transverse Dispersion in Liquid Flow Through Porous Media written by Eugene Sidney Simpson and published by . This book was released on 1962 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Christopher s Story written by John C. Rubisch, Ph.D. and published by First Edition Design Pub.. This book was released on 2015-07-23 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part biography, part social commentary, and part cold case, a compelling tale of the author's descent into his son's problems and the madness of the perpetual dysfunction of the country's mental health system. There is an astonishing level of detail taken from reports, evaluations, and the author's own journal entries, as he records his frustration, heartbreak, as well as a fair amount of humor. The MH system appears as bureaucratic maze of incompetence and callousness more interested in collecting insurance payments and protecting itself from liability than in assisting others. The failure of the system in the case of the author's son has disastrous results. Physically abused at the age of one and a half by his own biological father, the subject of this book commits physical abuse to an infant twenty-one years later with fatal consequences. And just when readers have thought it couldn't get any worse, there is a twist at the end that is beyond belief. Staring when the boy was four, the author writes of his efforts to raise his son by himself. It is clear from the beginning that Christopher has emotional problems, and the author seeks help. However, the boy is continuously misdiagnosed as ADHD with the solution being to try another medication. Indications that the boy is brain-damaged are ignored for many years. In school learning takes a back seat to behavior management. Adolescence brings violence, substance abuse, inappropriate sexual advances, and turns in and out of placements. At a crucial stage where both father and son are pleading for help, the MH system does not even return phone calls. Throughout the emphasis is on the failure of the MH system rather than the possible shortcomings of individuals. Pseudonyms are used to maintain the focus on the system. The author concludes by citing crucial points in his son's life were opportunities for interventions were missed. He also cites long standard practices in the MH field that deflect accountability and keep the system inefficient. Recommendations for changes in the system are made. In the book's final passage, the author citing a case of a student in the last year in which the recommendations by the MH system are totally inappropriate for the student. Keywords: Mental Health, Medication, Counseling, Brain Damage, Special Education, ADHD, Psychological Evaluation, Bender-Gestalt, Rubisch, MRI
Download or read book Self Assembling Systems written by Li-Tang Yan and published by John Wiley & Sons. This book was released on 2016-12-19 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides comprehensive knowledge on concepts, theoretical methods and state-of-the-art computational techniques for the simulation of self-assembling systems Looks at the field of self-assembly from a theoretical perspective Highlights the importance of theoretical studies and tailored computer simulations to support the design of new self-assembling materials with useful properties Divided into three parts covering the basic principles of self-assembly, methodology, and emerging topics
Download or read book Dynamic Light Scattering written by Wyn Brown and published by . This book was released on 1993-01-28 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Dynamic light scattering is an experimental technique now commonly found in laboratories concerned with fundamental studies of macromolecular systems"--Preface.
