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Special Issue "Enabling Technologies and Green Processes for Biorefinery Strategies and Biomass Valorization"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: closed (10 December 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Giancarlo Cravotto

Dipartimento di Scienza e Tecnologia del Farmaco, University of Turin, Turin 10125, Italy
Website | E-Mail
Interests: enabling technologies from lab scale to industrial applications; green chemistry; sustainable processes; plant extraction; process intensification
Guest Editor
Prof. Dr. Farid Chemat

Green Extraction Team, Université d'Avignon et des Pays de Vaucluse, INRA, Avignon Cedex 84029, France
Website | E-Mail
Phone: 0033490144465
Interests: green extraction; alternative solvents; innovative technologies; microwave; ultrasound

Special Issue Information

Dear Colleagues,

In the last decade, the development of alternative sustainable chemical processes has exploited suitable enabling technologies. Starting from a rational approach to biorefinery strategizing for agri-food waste valorization, the cost-effective production of high-value natural products and food ingredients and the recovery of co-products from food processing wastes are some of the main goals of all industrialized countries. In this context, a pivotal role is played by enabling technologies, such as ultrasound (US), microwaves (MW), and ball mills.

Compared to classic batch reactors, flow systems stand out for their greater efficiency and flexibility, and are well suited for high-throughput applications, due to the lower energy consumption. Flow-multihorn US reactors (a) and cavitational turbines (b) enable fast cell wall disruption via the intense cavitation and subsequent concentration of mobilized cytoplasmic material, even in simple water. Besides cryomilling applications, the mechanochemical technique opened the way to solventless plants extractions, with suitable solid matrices (cyclodextrins, adsorbing resins, oils), even at pilot (c) and industrial scales. Outstanding achievements have been obtained with MW-assisted processes, in particular with subcritical water (d) or pressurized water steam.

Bio-waste is generally a negative-cost feedstock for the potential production of high value-added chemicals and bioenergy. This Special Issue of Molecules aims to describe existing studies and applications of non-conventional energy sources within this field. Comparisons with classic procedures are a good means with which to highlight the huge advantages and potential scalabilities of these so-called “enabling technologies”.

Although many advances have been made during the past decade, the most exciting results in this field are surely yet to come.

 

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(a) Flow-multihorn ultrasonic reactor, (b) Cavitational turbine, (c) Pilot-scale ball mill, (d) High-pressure microwave reactor.

Prof. Dr. Cravotto Giancarlo
Prof. Dr. Farid Chemat
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


Keywords

  • biorefinery
  • green extraction
  • innovative techniques
  • valorization of byproducts
  • biomass for food, fuel, and ingredients

Published Papers (8 papers)

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Research

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Open AccessArticle Microwave-Assisted γ-Valerolactone Production for Biomass Lignin Extraction: A Cascade Protocol
Molecules 2016, 21(4), 413; doi:10.3390/molecules21040413
Received: 16 February 2016 / Revised: 11 March 2016 / Accepted: 18 March 2016 / Published: 26 March 2016
Cited by 6 | PDF Full-text (1998 KB) | HTML Full-text | XML Full-text
Abstract
The general need to slow the depletion of fossil resources and reduce carbon footprints has led to tremendous effort being invested in creating “greener” industrial processes and developing alternative means to produce fuels and synthesize platform chemicals. This work aims to design a
[...] Read more.
The general need to slow the depletion of fossil resources and reduce carbon footprints has led to tremendous effort being invested in creating “greener” industrial processes and developing alternative means to produce fuels and synthesize platform chemicals. This work aims to design a microwave-assisted cascade process for a full biomass valorisation cycle. GVL (γ-valerolactone), a renewable green solvent, has been used in aqueous acidic solution to achieve complete biomass lignin extraction. After lignin precipitation, the levulinic acid (LA)-rich organic fraction was hydrogenated, which regenerated the starting solvent for further biomass delignification. This process does not requires a purification step because GVL plays the dual role of solvent and product, while the reagent (LA) is a product of biomass delignification. In summary, this bio-refinery approach to lignin extraction is a cascade protocol in which the solvent loss is integrated into the conversion cycle, leading to simplified methods for biomass valorisation. Full article
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Open AccessFeature PaperArticle Bio-Based Solvents for Green Extraction of Lipids from Oleaginous Yeast Biomass for Sustainable Aviation Biofuel
Molecules 2016, 21(2), 196; doi:10.3390/molecules21020196
Received: 11 December 2015 / Accepted: 26 January 2016 / Published: 6 February 2016
Cited by 11 | PDF Full-text (2967 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Lipid-based oleaginous microorganisms are potential candidates and resources for the sustainable production of biofuels. This study was designed to evaluate the performance of several alternative bio-based solvents for extracting lipids from yeasts. We used experimental design and simulation with Hansen solubility simulations and
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Lipid-based oleaginous microorganisms are potential candidates and resources for the sustainable production of biofuels. This study was designed to evaluate the performance of several alternative bio-based solvents for extracting lipids from yeasts. We used experimental design and simulation with Hansen solubility simulations and the conductor-like screening model for realistic solvation (COSMO-RS) to simulate the solubilization of lipids in each of these solvents. Lipid extracts were analyzed by high performance thin-layer chromatography (HPTLC) to obtain the distribution of lipids classes and gas chromatography coupled with a flame ionization detector (GC/FID) to obtain fatty acid profiles. Our aim was to correlate simulation with experimentation for extraction and solvation of lipids with bio-based solvents in order to make a preliminary evaluation for the replacement of hexane to extract lipids from microorganisms. Differences between theory and practice were noted for several solvents, such as CPME, MeTHF and ethyl acetate, which appeared to be good candidates to replace hexane. Full article
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Open AccessArticle Synthesis of the Fatty Esters of Solketal and Glycerol-Formal: Biobased Specialty Chemicals
Molecules 2016, 21(2), 170; doi:10.3390/molecules21020170
Received: 22 December 2015 / Revised: 22 January 2016 / Accepted: 25 January 2016 / Published: 30 January 2016
Cited by 3 | PDF Full-text (1012 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The caprylic, lauric, palmitic and stearic esters of solketal and glycerol formal were synthesized with high selectivity and in good yields by a solvent-free acid catalyzed procedure. No acetal hydrolysis was observed, notwithstanding the acidic reaction conditions. Full article
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Open AccessArticle Comparative Study of Essential Oils Extracted from Egyptian Basil Leaves (Ocimum basilicum L.) Using Hydro-Distillation and Solvent-Free Microwave Extraction
Molecules 2016, 21(1), 113; doi:10.3390/molecules21010113
Received: 17 December 2015 / Revised: 10 January 2016 / Accepted: 15 January 2016 / Published: 19 January 2016
Cited by 2 | PDF Full-text (1733 KB) | HTML Full-text | XML Full-text
Abstract
Solvent-free microwave extraction (SFME) and conventional hydro-distillation (HD) were used for the extraction of essential oils (EOs) from Egyptian sweet basil (Ocimum basilicum L.) leaves. The two resulting EOs were compared with regards to their chemical composition, antioxidant, and antimicrobial activities. The
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Solvent-free microwave extraction (SFME) and conventional hydro-distillation (HD) were used for the extraction of essential oils (EOs) from Egyptian sweet basil (Ocimum basilicum L.) leaves. The two resulting EOs were compared with regards to their chemical composition, antioxidant, and antimicrobial activities. The EO analyzed by GC and GC-MS, presented 65 compounds constituting 99.3% and 99.0% of the total oils obtained by SFME and HD, respectively. The main components of both oils were linalool (43.5% SFME; 48.4% HD), followed by methyl chavicol (13.3% SFME; 14.3% HD) and 1,8-cineole (6.8% SFME; 7.3% HD). Their antioxidant activity were studied with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. The heating conditions effect was evaluated by the determination of the Total Polar Materials (TPM) content. The antimicrobial activity was investigated against five microorganisms: two Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis, two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, and one yeast, Candida albicans. Both EOs showed high antimicrobial, but weak antioxidant, activities. The results indicated that the SFME method may be a better alternative for the extraction of EO from O. basilicum since it could be considered as providing a richer source of natural antioxidants, as well as strong antimicrobial agents for food preservation. Full article
Open AccessArticle Low Temperature Soda-Oxygen Pulping of Bagasse
Molecules 2016, 21(1), 85; doi:10.3390/molecules21010085
Received: 9 December 2015 / Revised: 6 January 2016 / Accepted: 8 January 2016 / Published: 13 January 2016
Cited by 3 | PDF Full-text (1127 KB) | HTML Full-text | XML Full-text
Abstract
Wood shortages, environmental pollution and high energy consumption remain major obstacles hindering the development of today’s pulp and paper industry. Energy-saving and environmental friendly pulping processes are still needed, especially for non-woody materials. In this study, soda-oxygen pulping of bagasse was investigated and
[...] Read more.
Wood shortages, environmental pollution and high energy consumption remain major obstacles hindering the development of today’s pulp and paper industry. Energy-saving and environmental friendly pulping processes are still needed, especially for non-woody materials. In this study, soda-oxygen pulping of bagasse was investigated and a successful soda-oxygen pulping process for bagasse at 100 °C was established. The pulping parameters of choice were under active alkali charge of 23%, maximum cooking temperature 100 °C, time hold at maximum temperature 180 min, initial pressure of oxygen 0.6 MPa, MgSO4 charge 0.5%, and de-pithed bagasse consistency 12%. Properties of the resultant pulp were screened yield 60.9%, Kappa number 14, viscosity 766 dm3/kg, and brightness 63.7% ISO. Similar pulps were also obtained at 110 °C or 105 °C with a cooking time of 90 min. Compared with pulps obtained at higher temperatures (115–125 °C), this pulp had higher screened yield, brightness, and acceptable viscosity, while the delignification degree was moderate. These results indicated that soda-oxygen pulping at 100 °C, the lowest cooking temperature reported so far for soda-oxygen pulping, is a suitable process for making chemical pulp from bagasse. Pulping at lower temperature and using oxygen make it an environmental friendly and energy-saving pulping process. Full article
Open AccessArticle Hydrothermal Conversion of Giant Reed to Furfural and Levulinic Acid: Optimization of the Process under Microwave Irradiation and Investigation of Distinctive Agronomic Parameters
Molecules 2015, 20(12), 21232-21253; doi:10.3390/molecules201219760
Received: 12 October 2015 / Revised: 16 November 2015 / Accepted: 23 November 2015 / Published: 30 November 2015
Cited by 15 | PDF Full-text (3667 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The hydrothermal conversion of giant reed (Arundo donax L.) to furfural (FA) and levulinic acid (LA) was investigated in the presence of dilute hydrochloric acid. FA and LA yields were improved by univariate optimization of the main reaction parameters: concentration of the
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The hydrothermal conversion of giant reed (Arundo donax L.) to furfural (FA) and levulinic acid (LA) was investigated in the presence of dilute hydrochloric acid. FA and LA yields were improved by univariate optimization of the main reaction parameters: concentration of the acid catalyst, solid/liquid ratio of the reaction mixture, hydrolysis temperature, and reaction time. The catalytic performances were investigated adopting the efficient microwave (MW) irradiation, allowing significant energy and time savings. The best FA and LA yields were further confirmed using a traditionally heated autoclave reactor, giving very high results, when compared with the literature. Hydrolysis temperature and time were the main reaction variables to be carefully optimized: FA formation needed milder reaction conditions, while LA more severe ones. The effect of the crop management (e.g., harvest time) on FA/LA production was discussed, revealing that harvest time was not a discriminating parameter for the further optimization of both FA and LA production, due to the very high productivity of the giant reed throughout the year. The promising results demonstrate that giant reed represents a very interesting candidate for a very high contemporary production of FA and LA of up to about 70% and 90% of the theoretical yields, respectively. Full article
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Review

Jump to: Research

Open AccessReview Biofuels and Their Co-Products as Livestock Feed: Global Economic and Environmental Implications
Molecules 2016, 21(3), 285; doi:10.3390/molecules21030285
Received: 23 December 2015 / Revised: 3 February 2016 / Accepted: 24 February 2016 / Published: 29 February 2016
Cited by 10 | PDF Full-text (1515 KB) | HTML Full-text | XML Full-text | Correction
Abstract
This review studies biofuel expansion in terms of competition between conventional and advanced biofuels based on bioenergy potential. Production of advanced biofuels is generally more expensive than current biofuels because products are not yet cost competitive. What is overlooked in the discussion about
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This review studies biofuel expansion in terms of competition between conventional and advanced biofuels based on bioenergy potential. Production of advanced biofuels is generally more expensive than current biofuels because products are not yet cost competitive. What is overlooked in the discussion about biofuel is the contribution the industry makes to the global animal feed supply and land use for cultivation of feedstocks. The global ethanol industry produces 44 million metric tonnes of high-quality feed, however, the co-products of biodiesel production have a moderate impact on the feed market contributing to just 8–9 million tonnes of protein meal output a year. By economically displacing traditional feed ingredients co-products from biofuel production are an important and valuable component of the biofuels sector and the global feed market. The return of co-products to the feed market has agricultural land use (and GHG emissions) implications as well. The use of co-products generated from grains and oilseeds can reduce net land use by 11% to 40%. The proportion of global cropland used for biofuels is currently some 2% (30–35 million hectares). By adding co-products substituted for grains and oilseeds the land required for cultivation of feedstocks declines to 1.5% of the global crop area. Full article
Open AccessReview Sustainable Biomaterials: Current Trends, Challenges and Applications
Molecules 2016, 21(1), 48; doi:10.3390/molecules21010048
Received: 28 September 2015 / Revised: 21 December 2015 / Accepted: 21 December 2015 / Published: 30 December 2015
PDF Full-text (3166 KB) | HTML Full-text | XML Full-text
Abstract
Biomaterials and sustainable resources are two complementary terms supporting the development of new sustainable emerging processes. In this context, many interdisciplinary approaches including biomass waste valorization and proper usage of green technologies, etc., were brought forward to tackle future challenges pertaining to
[...] Read more.
Biomaterials and sustainable resources are two complementary terms supporting the development of new sustainable emerging processes. In this context, many interdisciplinary approaches including biomass waste valorization and proper usage of green technologies, etc., were brought forward to tackle future challenges pertaining to declining fossil resources, energy conservation, and related environmental issues. The implementation of these approaches impels its potential effect on the economy of particular countries and also reduces unnecessary overburden on the environment. This contribution aims to provide an overview of some of the most recent trends, challenges, and applications in the field of biomaterials derived from sustainable resources. Full article
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