Volume 1 Bioethanol Fuel Production Processes. I

Konur, O., Ed. 2023. Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1. Boca Raton, FL: CRC Press. https://doi.org/10.1201/9781003226536 eBook ISBN: 9781003226536, 416 pp.

This book presents research on biomass pretreatments, which are a fundamental part of bioethanol fuel production to make biomass more accessible. This book also includes an introductory section on the bioethanol fuels.

Bioethanol Fuel Production Processes. I: Biomass Pretreatments is the first volume in the Handbook of Bioethanol Fuels (Six-Volume Set). The primary pretreatments at the macro level are the biological chemical, hydrothermal, and mechanical pretreatments of the biomass. It also has an introductory section on the biomass pretreatments at large for bioethanol fuel production.

The major pretreatments at the micro level are the enzymatic and fungal pretreatments of the biomass as the biological pretreatments, acid, alkaline, ionic liquid, and organic solvent pretreatment pretreatments of the biomass as the chemical pretreatments, steam explosion and liquid hot water pretreatments of the biomass as the hydrothermal pretreatments, and milling, ultrasonic, and microwave pretreatments of the biomass as the mechanical pretreatments.

The first volume also indicates that a wide range of pretreatments stand alone or in combination with each other fractionate the biomass to its constituents of cellulose, lignin, and hemicellulose and improve both sugar and bioethanol fuel yield, making this bioethanol fuel more competitive in relation to crude oil- and natural gas-based fossil fuels.

This first volume is a valuable resource for the stakeholders primarily in the research fields of energy and fuels, chemical engineering, environmental science and engineering, biotechnology, microbiology, chemistry, physics, mechanical engineering, agricultural sciences, food science and engineering, materials science, biochemistry, genetics, molecular biology, plant sciences, water resources, economics, business, management, transportation science and technology, ecology, public, environmental and occupational health, social sciences, toxicology, multidisciplinary sciences, and humanities among others.

Part 1. Introduction to Bioethanol Fuels. 97 pp.

1. Konur, O. 2023a. Introduction to bioethanol fuels. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 3-46. Boca Raton, FL: CRC Press. 44 pp.

Crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in fuel cells, and in the biochemical and biohydrogen fuel production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of bioethanol prior to the bioethanol fuel production from feedstocks through hydrolysis of the biomass and fermentation of the resulting hydrolysates. Research in the field of bioethanol fuels has intensified in this context in key research fronts of the production of bioethanol fuels and to a lesser extent utilization and evaluation of bioethanol fuels. For the first research front, pretreatment and hydrolysis of feedstocks, fermentation of the feedstock-based hydrolysates, production of bioethanol fuels, and to a lesser extent distillation of bioethanol fuels are the key research areas while for the second research front, direct utilization of bioethanol fuels in fuel cells and transport engines, bioethanol-based biohydrogen fuels, bioethanol sensors, and bioethanol-based biochemicals have been the key research areas. Research in this field has also intensified for feedstocks of lignocellulosic biomass at large, bioethanol fuels for their utilization, cellulose, starch feedstock residues such as corn stover and wheat straw, wood biomass such as pine or oak, and to a lesser extent industrial waste such as glycerol, lignin, grass biomass such as switchgrass and miscanthus, hydrolysates, biomass at large, sugar feedstocks such as sugarcane, sugar feedstock residues such as sugarcane bagasse, algal biomass such as chlorella, lignocellulosic wastes at large such as food wastes, starch feedstocks such as corn and wheat, urban wastes such as used furniture, forestry wastes such as tree branches, food wastes such as spent coffee grounds, biosyngas, and plants such as water hyacinth. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance research in this field. Thus, this six-volume Handbook of Bioethanol Fuels assesses the research on the production, evaluation, and utilization of bioethanol fuels and their derivatives and coproducts and presents a representative sample of this interdisciplinary research population with a collection of 110 chapters.

2. Konur, O. 2023b. Bioethanol fuels: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 47-76. Boca Raton, FL: CRC Press. 30 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical and biohydrogen fuel production in a biorefinery context. Bioethanol fuels also play a critical role in maintaining the energy security in the supply shocks related to oil price shocks, COVID-19 pandemics, or wars in the aftermath of the Russian invasion of Ukraine. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis of the biomass and fermentation of the resulting hydrolysates. The research in the field of the bioethanol fuels has intensified in this context in the key research fronts of the production of bioethanol fuels, and to a lesser extent, utilization and evaluation of bioethanol fuels. For the first research front, pretreatment and hydrolysis of the feedstocks, fermentation of the feedstock-based hydrolysates, production of bioethanol fuels, and to a lesser extent distillation of bioethanol fuels are the key research areas whilst for the second research front, utilization of bioethanol fuels in fuel cells and transport engines, bioethanol-based biohydrogen fuels, bioethanol sensors, and bioethanol-based biochemicals are the key research areas. The research in this field has also intensified for the feedstocks of lignocellulosic biomass at large, bioethanol fuels for their utilization, cellulose, starch feedstock residues, wood biomass, and to a lesser extent industrial waste, lignin, grass, hydrolysates, biomass, sugar feedstocks, sugar feedstock residues, algal biomass, lignocellulosic wastes, starch feedstocks, urban wastes, forestry wastes, food wastes, syngas, and plants. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. The scientometric analysis has been used in this context to inform the primary stakeholders about the current state of the research in a selected research field. As there have been no published scientometric studies in this field, this book chapter presents a scientometric study of the research on the bioethanol fuels. It examines the scientometric characteristics of both the sample and population data presenting scientometric characteristics of these both datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, Scopus keywords, and research fronts.

3. Konur, O. 2023c. Bioethanol fuels: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 77-97. Boca Raton, FL: CRC Press. 21 pp.

Crude oil–based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in fuel cells, and in biochemical and biohydrogen fuel production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of bioethanol prior to bioethanol fuel production from the feedstocks through hydrolysis of the biomass and fermentation of resulting hydrolysates. Influential research in the field of bioethanol fuels has intensified in this context in the key research fronts of the production of bioethanol fuels and to a lesser extent utilization and evaluation of bioethanol fuels. For the first research front, pretreatment and hydrolysis of feedstocks and to a lesser extent production of bioethanol fuels in general and fermentation of hydrolysates are the key influential research areas while for the second research front, bioethanol-based biohydrogen fuels and bioethanol sensors are the key influential research areas. Influential research in this field has also intensified for feedstocks of wood biomass, cellulose, lignin, grass biomass, and bioethanol fuels and to a lesser extent lignocellulosic biomass at large, starch feedstock residues, starch feedstocks, biomass at large, and sugar feedstock residues. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance research in this field. Although there have been a large number of review papers on bioethanol fuels, there has been no review of the most-cited 25 articles in this field. Thus, this chapter presents a review of these most-cited 25 articles. Then, it discusses the key findings of these highly influential papers and comments on future research priorities in this field.

Part 2. Biomass Pretreatments for Bioethanol Production 289 Pp.

Part 2.1. Introduction to the Biomass Pretreatments for Bioethanol Production 41 pp.

4. Konur, O. 2023d. Biomass pretreatments: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 101-124. Boca Raton, FL: CRC Press. 24 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical and biohydrogen fuel production in a biorefinery context. Bioethanol fuels also play a critical role in maintaining the energy security in the supply shocks related to oil price shock or wars. The research in the fields of biomass pretreatments has also intensified in recent years as biological, chemical, and, to a lesser extent, mechanical and hydrothermal pretreatments of the biomass have been widely researched to increase the sugar and bioethanol yield in this context. On the individual terms, the most prolific pretreatments have been enzymatic hydrolysis and enzymatic, acid, ionic liquid, fungal, alkaline, other chemical, hydrothermal, and to a lesser extent steam explosion, ammonia, organic solvent, microbial, hot compressed water, milling, liquid hot water, and microwave pretreatments. Further, the most prolific biomass has been biomass constituents, biomass, in general, agricultural residues, wood and a lesser extent grass biomass at the macroscale and cellulose, lignin, lignocellulosic biomass at large, biomass at large, corn stover, lignocellulose, other residues, softwood, wheat straw, switchgrass, sugarcane bagasse, and hemicellulose at the microscale. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. The scientometric analysis has been used in this context to inform the primary stakeholders about the current state of the research in a selected research field. As there have been no scientometric studies on the biomass pretreatments, this book chapter presents a scientometric study of the research in biomass pretreatments. It examines the scientometric characteristics of both the sample and population data presenting scientometric characteristics of both datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, keywords, and research fronts.

5. Konur, O. 2023e. Biomass pretreatments: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 125-141. Boca Raton, FL: CRC Press. 17 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical and biohydrogen fuel production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis of the biomass and fermentation of the resulting hydrolysates. The research in the fields of biological, chemical, and, to a lesser extent, mechanical and hydrothermal pretreatments of the biomass has thus intensified in recent years. The most prolific pretreatments have been enzymatic hydrolysis, enzymatic pretreatments, ionic liquid pretreatments, fungal pretreatments, and, to a lesser extent, acid pretreatments and alkali pretreatments at the microscale. Further, the most used groups of the biomass have been biomass constituents and, to a lesser extent, wood, agricultural residues, and grass while the most used individual biomass and biomass constituents have been cellulose, lignin, wood, and, to a lesser extent, corn stover, softwood, switchgrass, wheat straw, and lignocellulosic biomass. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a number of review papers on the biomass pretreatments, there has been no review of the most- cited 25 articles in this field. Thus, this book chapter presents a review of the most-cited 25 articles in the field of the biomass pretreatments. Then, it discusses the key findings of these highly influential papers and comments on the future research priorities in this field.

Part 2.2. Biological Biomass Pretreatments for Bioethanol Production 289 pp.

6. Konur, O. (2023f). Biological pretreatment of the biomass: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 145-165. Boca Raton, FL: CRC Press. 21 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical and biohydrogen fuel production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis of the biomass and fermentation of the resulting hydrolysates. The research in the field of biological pretreatments of the biomass has also intensified in recent years in the research fronts of the enzymatic pretreatments, fungal pretreatments, enzymatic hydrolysis by primarily fungal enzymes, and to a lesser extent, microbial pretreatments of the biomass. Further, the research has intensified in the research fronts of biomass constituents, agricultural residues, biomass in general, wood, and to a lesser extent, grass and algae. However, on the individual terms, the most prolific biomass have been cellulose, lignin, wood, biomass in general, lignocellulose, and to a lesser extent, lignocellulosic biomass at large, corn stover, straw, and sugarcane bagasse. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. The scientometric analysis has been used in this context to inform the primary stakeholders about the current state of the research in a selected research field. Although there has been a number of review papers on the biological pretreatment of the biomass, there has been no review of the most-cited 25 articles in this field. Thus, this book chapter presents a scientometric study of the research on biological pretreatments of the biomass. It examines the scientometric characteristics of both the sample and population data presenting scientometric characteristics of both these datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, keywords, and research fronts.

7. Konur, O. (2023g). Biological pretreatment of the biomass: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 166-181. Boca Raton, FL: CRC Press. 16 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis of the biomass and fermentation of the hydrolysates. The research in the fields of biological pretreatments of the biomass has also intensified in recent years in the research fronts of the enzymatic hydrolysis by enzymes, enzymatic pretreatments, and to a lesser extent, fungal pretreatments of the biomass. Further, the most prolific groups of the biomass have been biomass constituents, wood, agricultural residues, biomass at large, and to a lesser extent, grass. Further, on individual terms, the most prolific biomass and biomass constituents have been lignin, wood, cellulose, corn stover, and to a lesser extent, straw, grass, biomass, lignocellulosic biomass, and cellulosic biomass. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a number of review papers on the biological pretreatment of the biomass, there has been no review of the most-cited 25 articles in this field. Thus, this book chapter presents a review of the most-cited 25 articles in the field of the biological pretreatments of the biomass. Then, it discusses the key findings of these highly influential papers and comments on the future research priorities in this field.

8. Thakur, S., R. Arora, A. Kumar and A. Pratush. 2023. Lignocellulolytic enzymes for biofuel production. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 182-194. Boca Raton, FL: CRC Press. 13 pp. Sonali Thakur, Richa Arora, Ajay Kumar, Amit Pratush

Lignocellulose bioconversion to produce biofuels has become an emerging research area to address some of the issues of environmental catastrophe. Despite extensive bioconversion research, the know-how used still suffers from certain technological barriers including biomass collection, costly pretreatment techniques, enzymatic hydrolysis, molding techniques, integration process, etc. The present chapter emphasizes the usage of extremophilic microorganisms for the production of inexpensive hydrolytic enzymes (cellulases, hemicellulases, and ligninases) for lignocellulosic biofuels. The current chapter also provides a detailed review of challenges in environmental risk assessment, potential explanations, and bioprocessing in the future for the sustainable use of thermozymes in biorefineries.

Part 2.3. Chemical Biomass Pretreatments for Bioethanol Production 69 pp.

9. Konur, O. (2023h). Chemical pretreatment of the biomass: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 197-217. Boca Raton, FL: CRC Press. 21 pp.

Crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels and in biochemical production in a biorefinery context. Research in the field of chemical pretreatments of biomass has also intensified in recent years. A number of chemical pretreatments such as acid, ionic liquid, and alkali and to a lesser extent ammonia organic solvent, ordinary solvent, hydrogen peroxide (H₂O₂), deep eutectic solvent, wet oxidation, supercritical water, surfactant, ozone (O₃), sulfite, and supercritical carbon dioxide (CO₂) pretreatments have been widely researched in this context to increase sugar and bioethanol yield in recent years. Further, the most prolific biomass groups used in these chemical pretreatments have been biomass constituents, agricultural residues, and biomass in general and to a lesser extent wood, grass, and other biomasses such as algae and plants. Additionally, on individual terms, the most prolific biomasses used in chemical pretreatments have been cellulose, corn stover, and lignocellulosic biomass and to a lesser extent wood, biomass at large, grass, rice straw, wheat straw, hemicellulose, sugarcane bagasse, lignocellulose, and cellobiose. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance research in this field. As there have been no scientometric studies on chemical pretreatments of biomass, this chapter presents a scientometric study of research on the chemical pretreatments of biomass. It examines the scientometric characteristics of both the sample and population data presenting the scientometric characteristics of these both datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, keywords, and research fronts.

10. Konur, O. (2023i). Chemical pretreatment of the biomass: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 218-234. Boca Raton, FL: CRC Press. 17 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis and fermentation of the biomass. The research in the field of chemical pretreatments of the biomass has also intensified in recent years in this context. Acid, ionic liquid (IL), and to a lesser extent supercritical water, alkaline, hydrogen peroxide, ammonia, organic solvent, ozone, and surfactant pretreatments of the biomass have been widely researched to increase the sugar and bioethanol yield in this context in recent years. On the other hand, there have been three primary groups of biomass used in these pretreatment studies: biomass constituents and to a lesser extent agricultural residues and wood. Further, on the individual terms, the most prolific biomass have been cellulose and to a lesser extent wood, lignin, corn stover, lignocellulose, grass, rice straw, and wheat straw. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a number of review papers on the chemical pretreatments of the biomass, there has been no updated review of the most-cited 25 articles in this field. Thus, this book chapter presents a review of the most-cited 25 articles in the field of the chemical pretreatments of the biomass. Then, it discusses the key findings of these highly influential papers and comments on the future research priorities in this field.

11. Elgharbawy, A. A. M., N. A. N. Azmi and M. Moniruzzaman. 2023 Advances of bioethanol production using ionic liquids. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 235-249. Boca Raton, FL: CRC Press. 15 pp. Amal A.M. Elgharbawy, Nor Azrini Nadiha Azmi, Muhammad Moniruzzaman

Ionic liquids (ILs) have been utilized significantly for biomass, particularly, lignocellulosic biomass processing which transforms eventually to bioenergy. ILs are getting more attention as they are environmental-friendly and can be designed for specific applications. To affordably manufacture high-grade biofuels and high-end biochemicals, appropriate pretreatment technologies are necessary for the breakdown of the complex biomass structure. Because of their emission profile, recyclability, low vapor pressure, and tunable features, ILs offer a lot of promise for energy-efficient biomass pretreatment where certain ILs can even be made from sustainable biomass feedstocks. However, a few issues are currently impeding the large-scale adoption of ILs, including the lack of detailed understanding of degradation and their high cost of production, which hinders process optimization. Despite these challenges, recent advances have been made to further investigate ILs as potential solvents for biomass processing and bioethanol production, and this chapter presents the latest progress in ILs-assisted bioethanol production from lignocellulosic biomass.

12. Zhang, Y and L. Wang. 2023. Emerging solvents for biomass pretreatment and their sustainability. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 250-263. Boca Raton, FL: CRC Press. 14 pp. Yi Zhang, Lei Wang

Our ecosystem is endangered by the increasing demand of resources and emission of pollutants, which requires urgent and innovative solutions such as fuels and chemicals produced from renewable sources and/or via more sustainable technologies. Lignocellulosic biomass is a promising candidate in bio-based energy and chemicals production because of its renewability. However, lignocellulosic biomass is recalcitrant due to its natural complex structure, and therefore, pretreatment is essential to break the interlinks between cellulose, hemicellulose, and lignin for further utilization. Emerging solvents, such as bio-based solvents, ionic liquids, deep eutectic solvents, and supercritical fluids, have been increasingly applied in biomass pretreatment. These emerging solvents are normally claimed as environmentally friendly and able to replace traditional solvents toward a sustainable chemistry, however without a holistic sustainable assessment. An incomprehensive evaluation from single perspective or failing to consider entire life cycles of solvents may lead to the environmental burden shifting. Herein, this chapter summarized typical emerging solvents in the field of biomass pretreatment, discussed criteria for solvents greenness definition, reviewed current comprehensive assessment studies on their selection, and proposed a framework incorporating USEtox model for their sustainability assessment which is a guidance for solvents design and development.

Part 2.4. Hydrothermal Biomass Pretreatments for Bioethanol Production 42 pp.

13. Konur, O. (2023j). Hydrothermal pretreatment of the biomass: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 267-288. Boca Raton, FL: CRC Press. 22 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical production in a biorefinery context. Bioethanol fuels also play a critical role in maintaining the energy security in the supply shocks related to oil price shock or wars in the aftermath of the Russian invasion of Ukraine. The research in the fields of hydrothermal pretreatments of the biomass has also intensified in recent years as steam explosion and liquid hot water (LHW)-based hydrothermal treatments such as LHW, hot-compressed water, and autohydrolysis pretreatments of the biomass have been widely researched to increase the sugar and bioethanol yield in this context. Further, the most-prolific biomass has been agricultural residues, wood biomass, biomass constituents, and to a lesser extent biomass in general and grass biomass at the macroscale. On the other hand, the most-prolific individual biomass used in the pretreatments has been lignin, corn stover, cellulose, and to a lesser extent wheat straw, sugarcane bagasse, eucalyptus, lignocellulosic biomass, wood, hemicellulose, poplar, spruce, grass, pine, and corncobs. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. The scientometric analysis has been used in this context to inform the primary stakeholders about the current state of the research in a selected research field. As there have been no scientometric studies on the hydrothermal pretreatments of the biomass, this book chapter presents a scientometric study of the research in hydrothermal pretreatments of the biomass. It examines the scientometric characteristics of both the sample and population data presenting scientometric characteristics of these both datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, keywords, and research fronts, as well as highly cited 25 papers.

14. Konur, O. (2023k). Hydrothermal pretreatment of the biomass: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 289-306. Boca Raton, FL: CRC Press. 18 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in the fuel cells, and in the biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis and fermentation of the biomass. The research in the fields of hydrothermal pretreatments of the biomass has also intensified in recent years. Steam explosion- and liquid hot water (LHW)-based hydrothermal treatments such as LHW, hot compressed water (HCW), and autohydrolysis pretreatments of the biomass have been widely researched to increase the sugar and bioethanol yield in this context. Further, the most prolific primary types of the biomass have been biomass constituents, wood, agricultural residues, and to a lesser extent biomass in general. Further, the most prolific individual biomass have been lignin, cellulose, hemicellulose, wood, corn stover, wheat straw, hardwood, and to a lesser extent softwood, sugarcane bagasse, corncobs, lignocellulosic biomass, and poplar. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a number of review papers on the hydrothermal pretreatment of the biomass, there has been no updated review of the most-cited 25 articles in this field. Thus, this book chapter presents a review of the most-cited 25 articles in the field of the hydrothermal pretreatments of the biomass. Then, it discusses the key findings of these highly influential papers and comments on the future research priorities in this field.

Part 2.5. Mechanical Biomass Pretreatments for Bioethanol Production 81 pp.

15. Konur, O. (2023l) Mechanical pretreatment of the biomass: Scientometric study. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 309-330. Boca Raton, FL: CRC Press. 22 pp.

The crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels and in the biochemical production in a biorefinery context. The research in the fields of mechanical pretreatments of the biomass has also intensified in recent years. Milling, microwave, and ultrasonic pretreatments of the biomass have been widely researched in this context to increase the bioethanol yield in recent years. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. As there have been no scientometric studies on the mechanical pretreatments of the biomass, this book chapter presents a scientometric study of the research in mechanical pretreatments of the biomass. It examines the scientometric characteristics of both the sample and population data presenting scientometric characteristics of these both datasets in the order of documents, authors, publication years, institutions, funding bodies, source titles, countries, Scopus subject categories, keywords, and research fronts as well as the 20 highly cited papers.

16. Konur, O. (2023m). Milling pretreatment of the biomass: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 331-346. Boca Raton, FL: CRC Press. 16 pp.

Crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in fuel cells, and in biochemical production in a biorefinery context. However, it is necessary to pretreat biomass to enhance the yield of the bioethanol before the bioethanol production through hydrolysis and fermentation of biomass. The milling pretreatment as a mechanical pretreatment has been one of these pretreatment methods intensifying primarily in the research fronts of ball milling (BM), disk milling (DM), and hammer milling (HM). The most prolific biomass has been agricultural wastes, cellulose, wood, and to a lesser extent plants. Furthermore, on individual terms, the most prolific biomass has been cellulose, wood, straw, and to a lesser extent corn stover, wood chips, sugarcane bagasse, corn, grass, algae, food wastes, and corncobs. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance research in this field. Although there have been several review papers on the milling pretreatment of biomass, there has been no review of the 25 most-cited articles in this field. Thus, this book chapter presents a review of the 25 most-cited articles in this field. Then, it discusses the key findings of these highly influential papers briefly and comments on future research priorities in this field.

17. Hoang, A. T. and Konur, O. (2023n) Microwave pretreatment of the biomass: Review. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 347-364. Boca Raton, FL: CRC Press. 18 pp. Anh Tuan Hoang.

Crude oil–based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in fuel cells, and in biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of bioethanol fuels prior to bioethanol production through the hydrolysis and fermentation of the biomass and hydrolysates, respectively. Microwave pretreatment has been one of these pretreatment methods. The most prolific biomasses have been straw, cellulose, and sugarcane bagasse, and to a lesser extent grass, wood, corn stover, and hulls. The influential research in this area shows that microwave pretreatments either alone or in combination with chemical, enzymatic, and hydrothermal pretreatments have been effective in disrupting the biomass, thus enhancing the yield of sugar and bioethanol. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a number of review papers on the microwave pretreatment of biomass, there has been no review of the most-cited 25 articles in this field. Thus, this chapter presents a review of the most-cited 25 articles in these fields. Then, it discusses the key findings of these highly influential papers and comments on future research priorities in this field.

18. Pradhan, D., Tsegaye, B., Mathew, S.S., Jiaswal, S., Jaiswal, A.K. (2023). Ultrasound-assisted pretreatment of lignocellulosic biomass for bioethanol production. In Bioethanol Fuel Production Processes I: Biomass Pretreatments, Handbook of Bioethanol Fuels: Production and Utilization Volume 1, O. Konur, pp. 365-387. Boca Raton, FL: CRC Press.23 pp. Dileswar Pradhan, Bahiru Tsegaye, Sneha S. Mathew, Swarna Jaiswal, Amit K. Jaiswal

The structural complexity of lignocellulosic biomass (LCB) hindered exploiting the vast applications of its valorized products. The production of bioethanol fuels from this biomass is highly influenced by the cost of pretreatments, hydrolysis, and separation processes. The coupling of two or more pretreatment technologies, either simultaneously or stepwise, has a great advantage in overcoming the biomass’s recalcitrant nature and in improving the product yields. Ultrasound-assisted pretreatment, hydrolysis, and fermentation technology show promising results for process intensifications of bioethanol production. Ultrasonication improves the productivity of bioethanol production by increasing the mass transfer kinetics and changing the cell morphology. Therefore, it has great potentials to reduce the cost and enhance the rate and yield of bioethanol production via the cavitation effect. Therefore, investigating the depolymerization and fractionations of LCB via ultrasound-assisted enzymatic hydrolysis, ultrasound-assisted pretreatment, and ultrasound-assisted fermentation process, as well as optimizing process conditions, opens the path for exploiting the full potentials of the technology as well as utilization of renewable resources. Thus, this book chapter reviews the research on ultrasound-assisted enzymatic hydrolysis, ultrasound-assisted pretreatment, and ultrasound-assisted fermentation processes.