Ultrasonic vibration - assisted pelleting and dilute acid pretreatment of cellulosic biomass for biofuel manufacturing

Doctor of PhilosophyDepartment of Industrial & Manufacturing Systems EngineeringZhijian PeiDonghai WangIn the U.S. and many other countries, the transportation sector is almost entirely dependent on petroleum-based fuels. In 2011, half of the petroleum used in the U.S. was imported. The dependence on foreign petroleum is a real threat to national energy security. Furthermore, the transportation sector is responsible for about 30% of U.S. greenhouse gas emissions and is growing faster than any other major economic sector. National energy security, economy, environment sustainability are all driving the U.S. to develop alternative liquid transportation fuels that are domestically produced and environmentally friendly. Promoting biofuel is one of the efforts to reduce the use of petroleum-based fuels in the transportation sector. Cellulosic biomass are abundant and diverse. Thus, the ability to produce biofuel from cellulosic biomass will be a key to making ethanol competitive with petroleum-based fuels. Ultrasonic vibration- assisted (UV-A) pelleting can increase not only the density of cellulosic biomass but also the sugar yield. This PhD dissertation consists of fourteen chapters. Firstly, an introduction of the research is given in Chapter 1. Chapters 2, 3, 4, and 5 present experimental investigations on effects of input variables in UV-A pelleting on pellet quality. Chapter 6 investigates effects of input variables on energy consumption in UV-A pelleting. Chapter 7 develops a predictive model for energy consumption in UV-A pelleting using the response surface method. Chapter 8 investigates effects of input variables on energy consumption, water usage, sugar yield, and pretreatment energy efficiency in dilute acid pretreatment. Chapter 9 develops a predictive model for energy consumption in dilute acid pretreatment using the response surface method. Chapter 10 studies ultrasonic vibration-assisted (UV-A) dilute acid pretreatment of poplar wood for biofuel manufacturing. Chapter 11 compares sugar yields in terms of total sugar yield and enzymatic hydrolysis sugar yield between two kinds of materials: pellets processed by UV-A pelleting and biomass not processed by UV-A pelleting in terms of total sugar yield and enzymatic hydrolysis sugar yield. Chapter 12 develops a physics-based temperature model to predict temperature in UV-A pelleting. Chapter 13 develops a physics-based density model to predict pellet density in UV-A pelleting. Finally, conclusions and contributions of this research are summarized in Chapter 14

Experimental investigations of utilizing cellulosic biomass for biofuel productions on multi-platforms

Doctor of PhilosophyDepartment of Industrial & Manufacturing Systems EngineeringMeng (Peter) ZhangBiofuels derived from cellulosic biomass offer one of the best near- to mid-term alternatives to fossil fuels. Consuming bioenergy instead of fossil fuels can reduce greenhouse gas emission and benefit to the nation’s energy security. The conversion can be done either on biochemical platform or thermochemical platform. Cellulosic bioethanol is developed as an alternative to petroleum-based liquid fuel on the biochemical platform. It can be used on its own as a sustainable liquid transportation fuel or blended with conventional transportation fuel. On thermochemical platform, combustion is proven to efficiently utilize biomass for heat and power generation by co-firing with coal. To efficient convert cellulosic biomass into biofuels, biomass need to go through size reduction for bioethanol conversion. Particle size is critically important to energy consumption in its preprocessing and the efficiency in bioconversion. In the application of co-firing, the resulting fuel quality after biomass densification is also crucial to make biomass a cost effective solid fuel. This research provide fundamental knowledges and insights in biofuel manufacturing on biochemical and thermochemical platforms. A guidance on the effect of particle size through the whole bioethanol conversion process is provided. An investigation on solid fuel upgrading effects from synchronized torrefaction and pelleting (STP) system is also performed. At last, a preliminary study of a pathway on integrating these two platforms of cellulosic biomass utilization is performed. This half thesis consists of 8 chapters. Firstly, an introduction of this research is given in Chapter 1.Secondly, Chapter 2 provides a literature review on cellulosic bioethanol conversion process. Chapter 3and 4 present a comprehensive study on effect of particle size in both biomass pre-processing and bio-conversion. Chapter 5 reviews application of biomass on thermochemical platform. Chapter 6 studies the fuel upgrading effect from using STP system. A preliminary study on integrating two platforms of cellulosic biomass utilizations is presented in Chapter 7. Finally, conclusions are presented in Chapter 8

Biofuel Manufacturing from Woody Biomass: Effects of Sieve Size Used in Biomass Size Reduction

Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes

Experimental and numerical investigation of biomass mechanical pre-processing

"July 2014."Dissertation supervisor/advisor: Dr. Ali Bulent Koc.Includes vita.In this study, mechanical properties of switchgrass and miscanthus were determined by tensile, compressive and shear tests in longitudinal (along the fiber) and transversal (cross the fiber) directions with special designed tools. A linear cutting platform and a data acquisition system were developed to investigate the biomass cutting performances using conventional cutting and ultrasonic-assisted cutting. Three different blades with 20 kHz vibration frequency were designed by using finite element analysis and verified by experimental modal analysis. Finite element analysis models of biomass cutting were developed to simulate the biomass cutting process. The simulation results showed that finite element analysis method could be used to design the ultrasonic blade and simulate the biomass cutting process. Biomass cutting experiments were carried out to investigate the effects of cutting speed, shear angle, blade profile and ultrasonication on the cutting force and energy consumption of switchgrass and miscanthus cutting. Experimental results showed that ultrasonic cutting could reduce the cutting force and the entire cutting energy consumption. The optimized energy consumption could be achieved when the cutting speed was about 1/3 of the ultrasonic blade vibration speed. For the biomass conventional cutting, the tested cutting speeds did not show obvious effects on cutting performances.Includes bibliographical references (pages 144-150)

Ultrasound irradiation in the production of ethanol from biomass

Ethanol produced from renewable biomass, such as lignocellulosic feedstock, is one of the alternative energy resources that can be environmentally friendly. However, physical and chemical barriers caused by the close association of the main components of lignocellulosic biomass, as well as starch, hinder the hydrolysis of cellulose and hemicellulose in lignocellulose as well as amylase and amylopectin in starch to fermentable sugars. One of the main goals of pretreatment for enzymatic hydrolysis is to increase the enzyme accessibility for improving digestibility of cellulose and starch. Ultrasound irradiation applied to cellulosic materials and starch-based feedstock was found to enhance the efficiency of hydrolysis and subsequently increase the sugar yield. Prior research conducted on applying ultrasonic technology for cellulose and starch pretreatment has considered a variety of effects on physical and chemical characteristics, hydrolysis efficiency and ethanol yield. This paper reviews the application of ultrasound irradiation to cellulose and starch prior to and during hydrolysis in terms of sugar and ethanol yields. It also addresses characteristics such as accessibility, crystallinity, degree of polymerization, morphological structure, swelling power, particle size and viscosity as influenced by ultrasonic treatment. © 2014 Elsevier Ltd

Degumming of Hemp Fibers Using Combined Microwave Energy and Deep Eutectic Solvent

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali process. Several analytical techniques were used to characterize and perform a comparative analysis of the degummed fibers. Results revealed that the fiber qualities, including fiber surface morphology and UV shielding performance of DES-treated fibers at 1:20 solid-liquor ratio (UPF value was 183.67) were higher than these from the traditional alkali treated (140.75) and untreated raw hemp fibers (127.47). FT-IR, SEM, NMR, and XRD confirmed that degumming using a Microwave-DES treatment at 1:20 solid-liquor ratio had a higher yield with respect to removal of gummy materials (lignin and hemicellulose, etc.). TGA and DSC also confirmed the higher thermal stability of DES-treated fibers. In addition, cellulose content in the Microwave-DES treated samples was increased to 44.82% - 49.95% which was comparable with the increased cellulose content (49.49%) of alkali treated fibers. All these data indicate the effective, less time-consuming, green, and environmentally sustainable protocol for manufacturing hemp fibers

Valorisation of rice straw by obtaining active compounds and cellulosic materials for the development of biodegradable food packaging systems

Tesis por compendio[ES] En esta tesis se obtuvieron fracciones celulósicas y extractos activos de paja de arroz mediante diferentes técnicas de extracción y purificación, utilizando agua como disolvente. Estas fracciones se incorporaron en películas de almidón y PLA, y en bicapas de almidón-PLA, para obtener materiales de envasado activos para extender la vida útil de diferentes alimentos. Los extractos obtenidos por combinación de ultrasonidos y calentamiento a reflujo (USHT) y con agua subcrítica (SWE) (a 160 °C (SWE-160) y 180 °C (SWE-180)) presentaron un alto contenido fenólico (37, 51 y 83 mg GAE.g-1 de extracto seco, respectivamente) y actividad antioxidante (6,3, 2,0 y 1,2 mg de extracto seco.mg-1 DPPH, respectivamente). Los extractos SWE fueron activos contra L. innocua y E. coli. Se aislaron fibras de celulosa (FC) del residuo insoluble de las diferentes extracciones. A pesar de las ligeras diferencias en el grado de purificación, los nuevos métodos dieron lugar a FCs con rendimientos más elevados que el método alcalino (35-39 % frente al 29 %), con cristalinidad (60-69 %), comportamiento térmico y relación de aspecto (20-60) similares. Se incorporaron fibras USHT al 1, 3 y 5 % (p/p) en películas termoprocesadas de almidón de maíz, y de almidón de maíz modificado térmicamente. La incorporación al 3 % dio lugar a películas con mejores propiedades funcionales. Los extractos activos (al 4, 6 y 8 % en peso) en la matriz de almidón, con o sin CF (3 %), dieron lugar a películas más extensibles y menos resistentes, con mayor capacidad de barrera al oxígeno. Las bolsas monodosis de aceite de girasol con estas películas activas y reforzadas redujeron eficazmente la oxidación. Las películas activas de PLA termoprocesado, con diferentes proporciones (2, 4 y 6 % p/p) del extracto USHT, presentaron color y propiedades mecánicas ligeramente peores, pero con mayor barrera al oxígeno. La cinética de liberación de los antioxidantes incorporados en simulantes alimentarios de diferente polaridad (A: productos acuosos; y D1: sistemas de aceite en agua), mostró que las películas con un 6% de extracto, tuvieron una capacidad antioxidante similar en simulantes con distinta polaridad. Se obtuvieron bicapas biodegradables laminando PLA, con y sin extracto USHT (6 %), y almidón termoplástico, con o sin FC USHT (3 %). Las bicapas mostraron mejor capacidad de barrera global que las monocapas. Sin embargo, la migración de compuestos entre capas dio lugar a películas menos rígidas y resistentes de lo esperado de la contribución del film de PLA. Las bicapas activas y reforzadas alargaron la vida útil de carne de cerdo refrigerada. Las películas de PLA con un 6 % (p/p) de los diferentes extractos (USHT, SWE-160 y SWE-180) presentaron menor resistencia mecánica y capacidad de barrera al vapor de agua, pero una mayor capacidad de barrera al oxígeno y a la luz UV. Además, estas películas, especialmente con el extracto SWE-180, alargaron la vida útil de la carne de cerdo refrigerada. Las FCs obtenidas con los diferentes métodos de purificación también se utilizaron para producir aerogeles de celulosa. Las diferencias composicionales afectaron a la microestructura de los aerogeles. La capacidad de absorción y de retención de agua de los aerogeles estuvo dentro de los rangos descritos para este tipo de materiales. Por tanto, fue posible obtener fracciones valorizadas de la paja de arroz, extractos activos y fibras celulósicas, útiles en el desarrollo de materiales biodegradables activos a base de almidón y PLA. Son necesarios más estudios para validar la seguridad alimentaria de los materiales, así como para el desarrollo de otras aplicaciones en el campo de la industria alimentaria o farmacéutica.[CA] En aquesta tesi doctoral es van obtenir fraccions cel·lulòsiques i extractes actius de palla d' arròs mitjançant l'aplicació de diferents tècniques d'extracció i purificació, utilitzant aigua com a dissolvent. Aquestes fraccions es van incorporar a pel·lícules de midó i PLA, i bicapes de midó-PLA, per obtenir materials d'envasament actius útils per allargar la vida útil de diferents aliments. Els extractes combinant ultrasons i escalfament a reflux (USHT) i amb aigua subcrítica (SWE) (a 160 °C (SWE-160) i 180 °C (SWE-180)) van mostrar un alt contingut fenòlic (37, 51 i 83 mg GAE.g-1 d'extracte sec, respectivament) i activitat antioxidant (6,3, 2,0 i 1,2 mg d'extracte sec.mg-1 DPPH, respectivament). Els extractes SWE van mostrar activitat antibacteriana contra L. innocua i E. coli. Es van aïllar fibres de cel·lulosa (FC) de les fraccions insolubles de l'extracció. Malgrat les lleugeres diferències en el grau de purificació, els nous mètodes van donar lloc a FCs amb rendiments més elevats que el mètode alcalí (35-39 % enfront del 29 %), amb cristal·linitat (60-69 %), comportament tèrmic i relació d'aspecte (20-60) similars. Es van incorporar fibres USHT a l'1, 3 i 5 % (p/p) en pel·lícules de midó de dacsa, i de midó de dacsa modificat per tractament tèrmic. La incorporació al 3 % va donar lloc a pel·lícules amb les millors propietats funcionals. Els extractes actius (al 4, 6 i 8 % en pes) a la matriu de midó, amb o sense CF (3 %), proporcionaren pel·lícules més extensibles i menys resistents, però amb més capacitat de barrera a l'oxigen. Les bosses monodosi de l'oli de gira-sol amb aquestes pel·lícules actives i reforçades van reduir eficaçment l'oxidació. Les pel·lícules actives de PLA amb diferents proporcions (2, 4 i 6 % p/p) de l'extracte USHT, presentaren color i propietats mecániques lleugerament pitjors, però amb major capacitat de barrera a l'oxigen. La cinètica d'alliberament dels antioxidants incorporats, en simulants alimentaris de diferent polaritat (A: productes aquosos; i D1: sistemes d'oli en aigua), va mostrar que les pel·lícules amb un 6% d'extracte, tenien una capacitat antioxidant similar en simulants amb diferent polaritat. Es van obtenir bicapes biodegradables laminant PLA, amb i sense extracte USHT (6 %), i midó termoplàstic, amb o sense FC USHT (3 %). Les bicapes van mostrar millor capacitat de barrera global que les monocapes. No obstant això, la migració de compostos entre capes va donar lloc a pel·lícules menys rígides i resistents respecte a l'esperat de la contribució de la pel·lícula de PLA. Les bicapes actives i reforçades van allargar la vida útil de carn de porc refrigerada. Les pel·lícules de PLA amb un 6 % (p/p) dels diferents extractes (USHT, SWE-160 i SWE-180) van presentar menor resistència mecànica i capacitat de barrera al vapor d'aigua, però una major capacitat de barrera a l'oxigen i a la llum UV. A més, aquestes pel·lícules, especialment amb l'extracte SWE-180, van allargar la vida útil de la carn de porc refrigerada. Les FCs obtingudes amb els diferents mètodes de purificació també es van utilitzar per produir aerogels de cel·lulosa. Les diferències composicionals van afectar la microestructura dels aerogels. La capacitat d' absorció i de retenció d'aigua dels aerogels va estar dins dels rangs descrits per a aquest tipus de materials. Per tant, va ser possible obtenir fraccions valoritzades de la palla d' arròs, extractes actius i fibres cel·lulòsiques, útils en el desenvolupament de materials biodegradables actius a base de midó i PLA. Són necessaris més estudis per validar la seguretat alimentària dels materials, així com per al desenvolupament d' altres aplicacions en el camp de la indústria alimentària o farmacèutica.[EN] This Doctoral thesis focused on obtaining cellulosic fractions and bioactive extracts from rice straw (RS) by applying different extraction and purification techniques, using water as a green solvent. These fractions were incorporated into starch and poly (lactic acid) (PLA)-based films, as well as into starch-PLA bilayers, to obtain active packaging materials useful for extending the shelf life of different food matrices. The extracts obtained by applying a combined ultrasound-reflux heating method (USHT) and subcritical water extraction (SWE) (at 160 °C (SWE-160) and 180 °C (SWE-180)) exhibited high phenolic content (37, 51, 83 mg GAE.g-1 dry extract, respectively) and antioxidant activity (6.3, 2.0, and 1.2 mg dry extract.mg-1 DPPH, respectively). The SWE extracts showed antibacterial activity against L. innocua and E. coli. Cellulose fibres (CF) were isolated from the extraction insoluble fractions and compared with those obtained from the traditional alkaline method. Despite slight differences in the degree of purification, the new methods gave rise to CFs with higher yields than the alkaline method (35-39% vs. 29%), with similar crystallinity (60-69%), thermal behaviour, and aspect ratios. USHT fibres were incorporated into corn starch (1, 3, and 5% wt.), and corn starch-modified by heat treatment, obtained by thermoprocessing. The incorporation of CF at 3% gave rise to films with the best functional properties. When active extracts were incorporated at different ratios (4, 6, and 8% wt.) into the starch matrix, with or without CF (3%), the films were more stretchable and less resistant, but with higher oxygen barrier capacity. Likewise, mono-dose bags of these active and reinforced films effectively reduced the oxidation of packed sunflower oil. Active, plasticised PLA films were produced, incorporating USHT extract (2, 4, and 6% wt.) by thermoprocessing, which exhibited colour and slightly worsened tensile behaviour, but with higher oxygen barrier capacity. The release kinetics of the incorporated antioxidant compounds in food simulants of different polarity (A: aqueous products; and D1: oil-in-water systems) showed that films containing 6% of extract delivered similar antioxidant capacity regardless of the food simulant polarity. Biodegradable bilayers were obtained by laminating plasticised PLA, with and without USHT extract (6%), and thermoplastic starch, with or without USHT CFs (3%). The bilayers exhibited improved overall barrier capacity with respect to the monolayers. However, the interlayer compound migration led to less stiff and resistant films with respect to that expected from the PLA film contribution. The active and reinforced bilayers were able to extend the shelf life of the packed pork meat during cold storage. PLA films with 6% wt. of the different extracts (USHT, SWE-160, and SWE-180) were produced, which exhibited lower mechanical resistance and water vapour barrier capacity, but improved oxygen barrier capacity and intense UV light-blocking effect. Furthermore, the active PLA films, especially with SWE-180 extract, extended the shelf life of cold storage pork meat. The CFs obtained with the different purification methods were also used to produce cellulose aerogels. The differences in the chemical composition of the CFs affected the aerogels' microstructure. The water absorption and retention capacity of the aerogels were within the previously reported ranges for this type of material. Thus, it was possible to obtain valorised fractions of rice straw, active extracts and cellulosic fibres, useful in developing active biodegradable materials based on starch and PLA. Further studies are needed to validate the food safety of the materials, as well as for developing other applications in the food or pharmaceutical industry.The authors thank the Agencia Estatal de Investigación (Spain) for the financial support through projects PID2019-105207RB-I00/AEI/10.13039/501100011033 and Generalitat Valenciana [grant number GrisoliaP/2019/115].Vieira De Freitas, PA. (2022). Valorisation of rice straw by obtaining active compounds and cellulosic materials for the development of biodegradable food packaging systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/191380Compendi

WP3 – Innovation in Agriculture and Forestry Sector for Energetic Sustainability

The papers published in this Special Issue “WP3—Innovation in Agriculture and Forestry Sector for Energetic Sustainability” bring together some of the latest research results in the field of biomass valorization and the process of energy production and climate change and other areas relevant to energetic sustainability [1–20]. Moreover, several works address the very important topic of evaluating the safety aspects for energy plant use [21–24]. Responses to our call generated the following statistics:• Submissions (21);• Publications (15);• Rejections (6);• Article types: research articles (13), reviews (2). Of the submitted papers, 15 have been successfully published as articles. Reviewing and selecting the papers for this Special Issue was very inspiring and rewarding. We also thank the editorial staff and reviewers for their efforts and help during the process. For better comprehension, the contributions to this Special Issue are divided into sections, as follows

Ultrasonic vibration-assisted pelleting of wheat straw: a predictive model for energy consumption using response surface methodology

Cellulosic biomass can be used as a feedstock for biofuel manufacturing. Pelleting of cellulosic biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1 g, and the minimum energy consumption was 2.54 Wh