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Exclusive Review Papers in Green Chemistry

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

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 49892

Special Issue Editors


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Guest Editor
Department of Drug Science and Technology, University of Turin, via P. Giuria 9, 10125 Turin, Italy
Interests: enabling technologies ind food extraction and processing; microwaves; ultrasound; hydrodinamic cavitation; SC-CO2; green solvents; bioactive natural products
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
“Petru Poni” Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41 A, 700487 Iasi, Romania
Interests: obtain new macromolecular architectures or ionic composites with applications in environment protection, medicine, cosmetics, food industry; functionalize and diversify the applications of some polysaccharides; obtain new soluble polyelectrolytes or some (organic or hybrid) ion exchangers with specific applications in environment protection; obtain new synthetic ionic polymers to be used as biocatalizers and insoluble organic catalizers or in the processes of retaining various organic and inorganic pollutants
Special Issues, Collections and Topics in MDPI journals
Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), Institute for Solar Fuels, Berlin, Germany
Interests: solar fuel; novel semiconductor photoelectrodes and photocatalysts; complex metal oxides; photoelectrochemistry; charge carrier dynamics; semiconductor-electrolyte interface; (photo)electrochemical engineering; scale-up of devices

Special Issue Information

Dear Colleagues,

This Special Issue aims to collect high-quality review papers in the research field of green chemistry, for which the Editorial Board members of the journal Molecules, Section “Green Chemistry”, and other researchers working in the field are invited to contribute.

We are welcoming proposals for review articles in this dynamically developing discipline in fundamental and applied research even in academia and industry in all domains such as fine chemicals, pharma, cosmetic, nutraceutical, food ingredients, perfumery, materials, paint, etc.

Prof. Dr. Giancarlo Cravotto
Dr. Ecaterina Stela Dragan
Dr. Giorgio Vilardi
Dr. Fatwa Abdi
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 submissions that pass pre-check are 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 semimonthly 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 2700 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

  • green catalysts
  • green extraction and processing
  • bio-based solvents
  • bioconversion of biomass
  • biomaterials
  • green analytical chemistry

Published Papers (17 papers)

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Review

36 pages, 7024 KiB  
Review
Is Micellar Catalysis Green Chemistry?
by Fabrizio Fabris, Markus Illner, Jens-Uwe Repke, Alessandro Scarso and Michael Schwarze
Molecules 2023, 28(12), 4809; https://doi.org/10.3390/molecules28124809 - 16 Jun 2023
Cited by 5 | Viewed by 3401
Abstract
Many years ago, twelve principles were defined for carrying out chemical reactions and processes from a green chemistry perspective. It is everyone’s endeavor to take these points into account as far as possible when developing new processes or improving existing ones. Especially in [...] Read more.
Many years ago, twelve principles were defined for carrying out chemical reactions and processes from a green chemistry perspective. It is everyone’s endeavor to take these points into account as far as possible when developing new processes or improving existing ones. Especially in the field of organic synthesis, a new area of research has thus been established: micellar catalysis. This review article addresses the question of whether micellar catalysis is green chemistry by applying the twelve principles to micellar reaction media. The review shows that many reactions can be transferred from an organic solvent to a micellar medium, but that the surfactant also has a crucial role as a solubilizer. Thus, the reactions can be carried out in a much more environmentally friendly manner and with less risk. Moreover, surfactants are being reformulated in their design, synthesis, and degradation to add extra advantages to micellar catalysis to match all the twelve principles of green chemistry. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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14 pages, 5267 KiB  
Review
Recent Progress in the Integration of CO2 Capture and Utilization
by Huanghao Ning, Yongdan Li and Cuijuan Zhang
Molecules 2023, 28(11), 4500; https://doi.org/10.3390/molecules28114500 - 01 Jun 2023
Cited by 4 | Viewed by 2027
Abstract
CO2 emission is deemed to be mainly responsible for global warming. To reduce CO2 emissions into the atmosphere and to use it as a carbon source, CO2 capture and its conversion into valuable chemicals is greatly desirable. To reduce the [...] Read more.
CO2 emission is deemed to be mainly responsible for global warming. To reduce CO2 emissions into the atmosphere and to use it as a carbon source, CO2 capture and its conversion into valuable chemicals is greatly desirable. To reduce the transportation cost, the integration of the capture and utilization processes is a feasible option. Here, the recent progress in the integration of CO2 capture and conversion is reviewed. The absorption, adsorption, and electrochemical separation capture processes integrated with several utilization processes, such as CO2 hydrogenation, reverse water–gas shift reaction, or dry methane reforming, is discussed in detail. The integration of capture and conversion over dual functional materials is also discussed. This review is aimed to encourage more efforts devoted to the integration of CO2 capture and utilization, and thus contribute to carbon neutrality around the world. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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17 pages, 4781 KiB  
Review
High Hydrostatic Pressure in the Modulation of Enzymatic and Organocatalysis and Life under Pressure: A Review
by Hana Scepankova, Diogo Galante, Edelman Espinoza-Suaréz, Carlos A. Pinto, Letícia M. Estevinho and Jorge Saraiva
Molecules 2023, 28(10), 4172; https://doi.org/10.3390/molecules28104172 - 18 May 2023
Cited by 1 | Viewed by 1646
Abstract
The interest in high hydrostatic pressure (HHP) is mostly focused on the inactivation of deleterious enzymes, considering the quality-related issues associated with enzymes in foods. However, more recently, HHP has been increasingly studied for several biotechnological applications, including the possibility of carrying out [...] Read more.
The interest in high hydrostatic pressure (HHP) is mostly focused on the inactivation of deleterious enzymes, considering the quality-related issues associated with enzymes in foods. However, more recently, HHP has been increasingly studied for several biotechnological applications, including the possibility of carrying out enzyme-catalyzed reactions under high pressure. This review aims to comprehensively present and discuss the effects of HHP on the kinetic catalytic action of enzymes and the equilibrium of the reaction when enzymatic reactions take place under pressure. Each enzyme can respond differently to high pressure, mainly depending on the pressure range and temperature applied. In some cases, the enzymatic reaction remains significantly active at high pressure and temperature, while at ambient pressure it is already inactivated or possesses minor activity. Furthermore, the effect of temperature and pressure on the enzymatic activity indicated a faster decrease in activity when elevated pressure is applied. For most cases, the product concentration at equilibrium under pressure increased; however, in some cases, hydrolysis was preferred over synthesis when pressure increased. The compiled evidence of the effect of high pressure on enzymatic activity indicates that pressure is an effective reaction parameter and that its application for enzyme catalysis is promising. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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31 pages, 10360 KiB  
Review
Lignin-Based Catalysts for C–C Bond-Forming Reactions
by Cristina del Mar García Martín, José Ignacio Hernández García, Sebastián Bonardd and David Díaz Díaz
Molecules 2023, 28(8), 3513; https://doi.org/10.3390/molecules28083513 - 16 Apr 2023
Cited by 2 | Viewed by 1523
Abstract
Carbon–carbon (C–C) bond formation is the key reaction in organic synthesis to construct the carbon framework of organic molecules. The continuous shift of science and technology toward eco-friendly and sustainable resources and processes has stimulated the development of catalytic processes for C–C bond [...] Read more.
Carbon–carbon (C–C) bond formation is the key reaction in organic synthesis to construct the carbon framework of organic molecules. The continuous shift of science and technology toward eco-friendly and sustainable resources and processes has stimulated the development of catalytic processes for C–C bond formation based on the use of renewable resources. In this context, and among other biopolymer-based materials, lignin has attracted scientific attention in the field of catalysis during the last decade, either through its acid form or as a support for metal ions and metal nanoparticles that drive the catalytic activity. Its heterogeneous nature, as well as its facile preparation and low cost, provide competitive advantages over other homogeneous catalysts. In this review, we have summarized a variety of C–C formation reactions, such as condensations, Michael additions of indoles, and Pd-mediated cross-coupling reactions that were successfully carried out in the presence of lignin-based catalysts. These examples also involve the successful recovery and reuse of the catalyst after the reaction. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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55 pages, 10330 KiB  
Review
Ion-Imprinted Polymeric Materials for Selective Adsorption of Heavy Metal Ions from Aqueous Solution
by Maria Marinela Lazar, Claudiu-Augustin Ghiorghita, Ecaterina Stela Dragan, Doina Humelnicu and Maria Valentina Dinu
Molecules 2023, 28(6), 2798; https://doi.org/10.3390/molecules28062798 - 20 Mar 2023
Cited by 12 | Viewed by 3378
Abstract
The introduction of selective recognition sites toward certain heavy metal ions (HMIs) is a great challenge, which has a major role when the separation of species with similar physicochemical features is considered. In this context, ion-imprinted polymers (IIPs) developed based on the principle [...] Read more.
The introduction of selective recognition sites toward certain heavy metal ions (HMIs) is a great challenge, which has a major role when the separation of species with similar physicochemical features is considered. In this context, ion-imprinted polymers (IIPs) developed based on the principle of molecular imprinting methodology, have emerged as an innovative solution. Recent advances in IIPs have shown that they exhibit higher selectivity coefficients than non-imprinted ones, which could support a large range of environmental applications starting from extraction and monitoring of HMIs to their detection and quantification. This review will emphasize the application of IIPs for selective removal of transition metal ions (including HMIs, precious metal ions, radionuclides, and rare earth metal ions) from aqueous solution by critically analyzing the most relevant literature studies from the last decade. In the first part of this review, the chemical components of IIPs, the main ion-imprinting technologies as well as the characterization methods used to evaluate the binding properties are briefly presented. In the second part, synthesis parameters, adsorption performance, and a descriptive analysis of solid phase extraction of heavy metal ions by various IIPs are provided. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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28 pages, 4948 KiB  
Review
Rheology as a Tool for Fine-Tuning the Properties of Printable Bioinspired Gels
by Maria Bercea
Molecules 2023, 28(6), 2766; https://doi.org/10.3390/molecules28062766 - 19 Mar 2023
Cited by 12 | Viewed by 2796
Abstract
Over the last decade, efforts have been oriented toward the development of suitable gels for 3D printing, with controlled morphology and shear-thinning behavior in well-defined conditions. As a multidisciplinary approach to the fabrication of complex biomaterials, 3D bioprinting combines cells and biocompatible materials, [...] Read more.
Over the last decade, efforts have been oriented toward the development of suitable gels for 3D printing, with controlled morphology and shear-thinning behavior in well-defined conditions. As a multidisciplinary approach to the fabrication of complex biomaterials, 3D bioprinting combines cells and biocompatible materials, which are subsequently printed in specific shapes to generate 3D structures for regenerative medicine or tissue engineering. A major interest is devoted to the printing of biomimetic materials with structural fidelity after their fabrication. Among some requirements imposed for bioinks, such as biocompatibility, nontoxicity, and the possibility to be sterilized, the nondamaging processability represents a critical issue for the stability and functioning of the 3D constructs. The major challenges in the field of printable gels are to mimic at different length scales the structures existing in nature and to reproduce the functions of the biological systems. Thus, a careful investigation of the rheological characteristics allows a fine-tuning of the material properties that are manufactured for targeted applications. The fluid-like or solid-like behavior of materials in conditions similar to those encountered in additive manufacturing can be monitored through the viscoelastic parameters determined in different shear conditions. The network strength, shear-thinning, yield point, and thixotropy govern bioprintability. An assessment of these rheological features provides significant insights for the design and characterization of printable gels. This review focuses on the rheological properties of printable bioinspired gels as a survey of cutting-edge research toward developing printed materials for additive manufacturing. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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11 pages, 1123 KiB  
Review
Carotenoid Content and Profiles of Pumpkin Products and By-Products
by Antonela Ninčević Grassino, Suzana Rimac Brnčić, Marija Badanjak Sabolović, Jana Šic Žlabur, Roko Marović and Mladen Brnčić
Molecules 2023, 28(2), 858; https://doi.org/10.3390/molecules28020858 - 15 Jan 2023
Cited by 13 | Viewed by 3463
Abstract
The goal of this review is to provide an overview of the current findings on the major carotenoids and their content in pumpkin products and by-products. The content of total carotenoids and the composition of carotenoids in pumpkins depend mainly on the species [...] Read more.
The goal of this review is to provide an overview of the current findings on the major carotenoids and their content in pumpkin products and by-products. The content of total carotenoids and the composition of carotenoids in pumpkins depend mainly on the species and cultivar, pedoclimatic conditions, the part of the plant (pulp, peel or seed), extraction procedures and the type of solvent used for extraction. The major carotenoids identified in pumpkins were β-carotene, α-carotene, lutein and zeaxanthin. β-Carotene is the major carotenoid in most pumpkin species. The number and content of total carotenoids are higher when minor carotenoids and ester forms are considered. The use of carotenoids in the development of functional foods has been the topic of many versatile studies in recent years, as they add significant value to foods associated with numerous health benefits. In view of this, pumpkin and pumpkin by-products can serve as a valuable source of carotenoids. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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36 pages, 13253 KiB  
Review
Combination of Enzymes and Deep Eutectic Solvents as Powerful Toolbox for Organic Synthesis
by Davide Arnodo, Elia Maffeis, Francesco Marra, Stefano Nejrotti and Cristina Prandi
Molecules 2023, 28(2), 516; https://doi.org/10.3390/molecules28020516 - 05 Jan 2023
Cited by 16 | Viewed by 2653
Abstract
During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have [...] Read more.
During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have been reported, making use of eutectic mixtures as reaction media, as an improvement in terms of selectivity and sustainability. This review aims to show the newly reported protocols in the field, subdivided by reaction class as a ‘toolbox’ guide for organic synthesis. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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43 pages, 53629 KiB  
Review
Polysaccharide-Based Composite Hydrogels as Sustainable Materials for Removal of Pollutants from Wastewater
by Claudiu-Augustin Ghiorghita, Maria Valentina Dinu, Maria Marinela Lazar and Ecaterina Stela Dragan
Molecules 2022, 27(23), 8574; https://doi.org/10.3390/molecules27238574 - 05 Dec 2022
Cited by 22 | Viewed by 2637
Abstract
Nowadays, pollution has become the main bottleneck towards sustainable technological development due to its detrimental implications in human and ecosystem health. Removal of pollutants from the surrounding environment is a hot research area worldwide; diverse technologies and materials are being continuously developed. To [...] Read more.
Nowadays, pollution has become the main bottleneck towards sustainable technological development due to its detrimental implications in human and ecosystem health. Removal of pollutants from the surrounding environment is a hot research area worldwide; diverse technologies and materials are being continuously developed. To this end, bio-based composite hydrogels as sorbents have received extensive attention in recent years because of advantages such as high adsorptive capacity, controllable mechanical properties, cost effectiveness, and potential for upscaling in continuous flow installations. In this review, we aim to provide an up-to-date analysis of the literature on recent accomplishments in the design of polysaccharide-based composite hydrogels for removal of heavy metal ions, dyes, and oxyanions from wastewater. The correlation between the constituent polysaccharides (chitosan, cellulose, alginate, starch, pectin, pullulan, xanthan, salecan, etc.), engineered composition (presence of other organic and/or inorganic components), and sorption conditions on the removal performance of addressed pollutants will be carefully scrutinized. Particular attention will be paid to the sustainability aspects in the selected studies, particularly to composite selectivity and reusability, as well as to their use in fixed-bed columns and real wastewater applications. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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29 pages, 6144 KiB  
Review
Application of Biobased Solvents in Asymmetric Catalysis
by Margherita Miele, Veronica Pillari, Vittorio Pace, Andrés R. Alcántara and Gonzalo de Gonzalo
Molecules 2022, 27(19), 6701; https://doi.org/10.3390/molecules27196701 - 08 Oct 2022
Cited by 8 | Viewed by 2254
Abstract
The necessity of more sustainable conditions that follow the twelve principles of Green Chemistry have pushed researchers to the development of novel reagents, catalysts and solvents for greener asymmetric methodologies. Solvents are in general a fundamental part for developing organic processes, as well [...] Read more.
The necessity of more sustainable conditions that follow the twelve principles of Green Chemistry have pushed researchers to the development of novel reagents, catalysts and solvents for greener asymmetric methodologies. Solvents are in general a fundamental part for developing organic processes, as well as for the separation and purification of the reaction products. By this reason, in the last years, the application of the so-called green solvents has emerged as a useful alternative to the classical organic solvents. These solvents must present some properties, such as a low vapor pressure and toxicity, high boiling point and biodegradability, and must be obtained from renewable sources. In the present revision, the recent application of these biobased solvents in the synthesis of optically active compounds employing different catalytic methodologies, including biocatalysis, organocatalysis and metal catalysis, will be analyzed to provide a novel tool for carrying out more ecofriendly organic processes. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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28 pages, 964 KiB  
Review
New Green Approaches in Nanoparticles Synthesis: An Overview
by Bogdan Andrei Miu and Anca Dinischiotu
Molecules 2022, 27(19), 6472; https://doi.org/10.3390/molecules27196472 - 01 Oct 2022
Cited by 29 | Viewed by 5214
Abstract
Nanotechnology is constantly expanding, with nanomaterials being more and more used in common commercial products that define our modern life. Among all types of nanomaterials, nanoparticles (NPs) occupy an important place, considering the great amount that is produced nowadays and the diversity of [...] Read more.
Nanotechnology is constantly expanding, with nanomaterials being more and more used in common commercial products that define our modern life. Among all types of nanomaterials, nanoparticles (NPs) occupy an important place, considering the great amount that is produced nowadays and the diversity of their applications. Conventional techniques applied to synthesize NPs have some issues that impede them from being appreciated as safe for the environment and health. The alternative to these might be the use of living organisms or biological extracts that can be involved in the green approach synthesis of NPs, a process that is free of harmful chemicals, cost-effective and a low energy consumer. Several factors, including biological reducing agent concentration, initial precursor salt concentration, agitation, reaction time, pH, temperature and light, can influence the characteristics of biologically synthesized NPs. The interdependence between these reaction parameters was not explored, being the main impediment in the implementation of the biological method on an industrial scale. Our aim is to present a brief review that focuses on the current knowledge regarding how the aforementioned factors can control the size and shape of green-synthesized NPs. We also provide an overview of the biomolecules that were found to be suitable for NP synthesis. This work is meant to be a support for researchers who intend to develop new green approaches for the synthesis of NPs. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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31 pages, 8499 KiB  
Review
Recent Progress in the Multicomponent Synthesis of Pyran Derivatives by Sustainable Catalysts under Green Conditions
by Suresh Maddila, Nagaraju Kerru and Sreekantha Babu Jonnalagadda
Molecules 2022, 27(19), 6347; https://doi.org/10.3390/molecules27196347 - 26 Sep 2022
Cited by 10 | Viewed by 1828
Abstract
Pyrans are one of the most significant skeletons of oxygen-containing heterocyclic molecules, which exhibit a broad spectrum of medicinal applications and are constituents of diverse natural product analogues. Various biological applications of these pyran analogues contributed to the growth advances in these oxygen-containing [...] Read more.
Pyrans are one of the most significant skeletons of oxygen-containing heterocyclic molecules, which exhibit a broad spectrum of medicinal applications and are constituents of diverse natural product analogues. Various biological applications of these pyran analogues contributed to the growth advances in these oxygen-containing molecules. Green one-pot methodologies for synthesising these heterocyclic molecules have received significant attention. This review focuses on the recent developments in synthesising pyran ring derivatives using reusable catalysts and emphasises the multicomponent reaction strategies using green protocols. The advantages of the catalysts in terms of yields, reaction conditions, and recyclability are discussed. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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19 pages, 11165 KiB  
Review
Electrospun Polymer Materials with Fungicidal Activity: A Review
by Nasko Nachev, Mariya Spasova, Nevena Manolova, Iliya Rashkov and Mladen Naydenov
Molecules 2022, 27(17), 5738; https://doi.org/10.3390/molecules27175738 - 05 Sep 2022
Cited by 1 | Viewed by 1781
Abstract
In recent years, there has been special interest in innovative technologies such as polymer melt or solution electrospinning, electrospraying, centrifugal electrospinning, coaxial electrospinning, and others. Applying these electrokinetic methods, micro- or nanofibrous materials with high specific surface area, high porosity, and various designs [...] Read more.
In recent years, there has been special interest in innovative technologies such as polymer melt or solution electrospinning, electrospraying, centrifugal electrospinning, coaxial electrospinning, and others. Applying these electrokinetic methods, micro- or nanofibrous materials with high specific surface area, high porosity, and various designs for diverse applications could be created. By using these techniques it is possible to obtain fibrous materials from both synthetic and natural biocompatible and biodegradable polymers, harmless to the environment. Incorporation of low-molecular substances with biological activity (e.g., antimicrobial, antifungal) is easily feasible. Moreover, biocontrol agents, able to suppress the development and growth of plant pathogens, have been embedded in the fibrous materials as well. The application of such nanotechnologies for the creation of plant protection products is an extremely promising new direction. This review emphasizes the recent progress in the development of electrospun fungicidal dressings and their potential to be applied in modern agriculture. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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45 pages, 12738 KiB  
Review
Recent Advances in Photocatalytic Oxidation of Methane to Methanol
by Gita Yuniar, Wibawa Hendra Saputera, Dwiwahju Sasongko, Rino R. Mukti, Jenny Rizkiana and Hary Devianto
Molecules 2022, 27(17), 5496; https://doi.org/10.3390/molecules27175496 - 26 Aug 2022
Cited by 9 | Viewed by 3527
Abstract
Methane is one of the promising alternatives to non-renewable petroleum resources since it can be transformed into added-value hydrocarbon feedstocks through suitable reactions. The conversion of methane to methanol with a higher chemical value has recently attracted much attention. The selective oxidation of [...] Read more.
Methane is one of the promising alternatives to non-renewable petroleum resources since it can be transformed into added-value hydrocarbon feedstocks through suitable reactions. The conversion of methane to methanol with a higher chemical value has recently attracted much attention. The selective oxidation of methane to methanol is often considered a “holy grail” reaction in catalysis. However, methanol production through the thermal catalytic process is thermodynamically and economically unfavorable due to its high energy consumption, low catalyst stability, and complex reactor maintenance. Photocatalytic technology offers great potential to carry out unfavorable reactions under mild conditions. Many in-depth studies have been carried out on the photocatalytic conversion of methane to methanol. This review will comprehensively provide recent progress in the photocatalytic oxidation of methane to methanol based on materials and engineering perspectives. Several aspects are considered, such as the type of semiconductor-based photocatalyst (tungsten, titania, zinc, etc.), structure modification of photocatalyst (doping, heterojunction, surface modification, crystal facet re-arrangement, and electron scavenger), factors affecting the reaction process (physiochemical characteristic of photocatalyst, operational condition, and reactor configuration), and briefly proposed reaction mechanism. Analysis of existing challenges and recommendations for the future development of photocatalytic technology for methane to methanol conversion is also highlighted. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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21 pages, 2376 KiB  
Review
Improving the Enzymatic Cascade of Reactions for the Reduction of CO2 to CH3OH in Water: From Enzymes Immobilization Strategies to Cofactor Regeneration and Cofactor Suppression
by Carmela Di Spiridione, Michele Aresta and Angela Dibenedetto
Molecules 2022, 27(15), 4913; https://doi.org/10.3390/molecules27154913 - 02 Aug 2022
Cited by 6 | Viewed by 2701
Abstract
The need to decrease the concentration of CO2 in the atmosphere has led to the search for strategies to reuse such molecule as a building block for chemicals and materials or a source of carbon for fuels. The enzymatic cascade of reactions [...] Read more.
The need to decrease the concentration of CO2 in the atmosphere has led to the search for strategies to reuse such molecule as a building block for chemicals and materials or a source of carbon for fuels. The enzymatic cascade of reactions that produce the reduction of CO2 to methanol seems to be a very attractive way of reusing CO2; however, it is still far away from a potential industrial application. In this review, a summary was made of all the advances that have been made in research on such a process, particularly on two salient points: enzyme immobilization and cofactor regeneration. A brief overview of the process is initially given, with a focus on the enzymes and the cofactor, followed by a discussion of all the advances that have been made in research, on the two salient points reported above. In particular, the enzymatic regeneration of NADH is compared to the chemical, electrochemical, and photochemical conversion of NAD+ into NADH. The enzymatic regeneration, while being the most used, has several drawbacks in the cost and life of enzymes that suggest attempting alternative solutions. The reduction in the amount of NADH used (by converting CO2 electrochemically into formate) or even the substitution of NADH with less expensive mimetic molecules is discussed in the text. Such an approach is part of the attempt made to take stock of the situation and identify the points on which work still needs to be conducted to reach an exploitation level of the entire process. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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24 pages, 6806 KiB  
Review
Lignin as a Natural Carrier for the Efficient Delivery of Bioactive Compounds: From Waste to Health
by Federico Verdini, Emanuela Calcio Gaudino, Erica Canova, Silvia Tabasso, Paria Jafari Behbahani and Giancarlo Cravotto
Molecules 2022, 27(11), 3598; https://doi.org/10.3390/molecules27113598 - 03 Jun 2022
Cited by 22 | Viewed by 3470
Abstract
Lignin is a fascinating aromatic biopolymer with high valorization potentiality. Besides its extensive value in the biorefinery context, as a renewable source of aromatics lignin is currently under evaluation for its huge potential in biomedical applications. Besides the specific antioxidant and antimicrobial activities [...] Read more.
Lignin is a fascinating aromatic biopolymer with high valorization potentiality. Besides its extensive value in the biorefinery context, as a renewable source of aromatics lignin is currently under evaluation for its huge potential in biomedical applications. Besides the specific antioxidant and antimicrobial activities of lignin, that depend on its source and isolation procedure, remarkable progress has been made, over the last five years, in the isolation, functionalization and modification of lignin and lignin-derived compounds to use as carriers for biologically active substances. The aim of this review is to summarize the current state of the art in the field of lignin-based carrier systems, highlighting the most important results. Furthermore, the possibilities and constraints related to the physico–chemical properties of the lignin source will be reviewed herein as well as the modifications and processing required to make lignin suitable for the loading and release of active compounds. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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33 pages, 2113 KiB  
Review
Microalgae Biomass as a New Potential Source of Sustainable Green Lubricants
by Leonardo I. Farfan-Cabrera, Mariana Franco-Morgado, Armando González-Sánchez, José Pérez-González and Benjamín M. Marín-Santibáñez
Molecules 2022, 27(4), 1205; https://doi.org/10.3390/molecules27041205 - 11 Feb 2022
Cited by 15 | Viewed by 3447
Abstract
Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. [...] Read more.
Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. However, production, usage and disposal of these lubricants have significant impact on environment and health. Hence, there is a growing pressure to reduce demand of this sort of lubricants, which has fostered development and use of green lubricants, as vegetable oil-based lubricants (biolubricants). Despite the ecological benefits of producing/using biolubricants, availability of the required raw materials and agricultural land to create a reliable chain supply is still far from being established. Recently, biomass from some microalgae species has attracted attention due to their capacity to produce high-value lipids/oils for potential lubricants production. Thus, this multidisciplinary work reviews the main chemical-physical characteristics of lubricants and the main attempts and progress on microalgae biomass production for developing oils with pertinent lubricating properties. In addition, potential microalgae strains and chemical modifications to their oils to produce lubricants for different industrial applications are identified. Finally, a guide for microalgae oil selection based on its chemical composition for specific lubricant applications is provided. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Green Chemistry)
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