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Clean Technol.
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Green Process Engineering
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Green Process Engineering

A special issue of Clean Technologies (ISSN 2571-8797).

Deadline for manuscript submissions: closed (15 January 2021) | Viewed by 70097

Special Issue Editors

Prof. Dr. Patrick Cognet

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Guest Editor
Laboratoire de Génie Chimique, Université de Toulouse, CNRS / INPT / UPS, Toulouse, France
Interests: green process engineering; kinetic modeling; catalyst; kinetics; chemical reaction engineering; reaction kinetics; chemical processes; process modeling; process optimization; heterogeneous catalysis
Prof. Christophe Gourdon

E-Mail Website
Guest Editor
Laboratoire de Génie Chimique, Laboratoire de Génie Chimique, Université de Toulouse, CNRS / INPT / UPS, Toulouse, France
Interests: green process engineering; process intensification, chemical reaction engineering; reaction kinetics; chemical processes; process modeling; process optimization; separation processes

Special Issue Information

Dear Colleagues,

The Special Issue “Green Process Engineering” provides a unique opportunity to achieve a comprehensive point of view of the different research efforts being carried out to achieve sustainability in the development of chemical processes, integrating a diversity of chemical and engineering aspects that contribute to reducing their environmental impact. More precisely, it focuses on different aspects: activation methods, process intensification, processes for biomass valorization, green product design and engineering sustainability, process design, LCA approach, modeling and optimization, new reaction media and green solvents, biocatalytic processes, and so on.

Preferably, articles should include an analysis or at least an indication of the sustainability of the technology or process considered.

We invite all researchers active in the broad and captivating domain of Green Process Engineering to submit articles for this Special Issue of the newly launched Clean Technologies journal.

Prof. Dr. Patrick Cognet
Prof. Dr. Christophe Gourdon
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. Clean Technologies is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Free publication for well-prepared manuscripts submitted before 31 December 2019. 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

  • cleaner production and technical processes
  • industrial chemistry and chemical engineering
  • production and process engineering
  • clean processes
  • renewable energies
  • green chemistry
  • sustainable development
  • environmentally-friendly technology
  • analysis and improvement of traditional technology and sources of pollution
  • energy-saving technology

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Further information on MDPI's Special Issue polices can be found here.

Published Papers (11 papers)

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Research

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5 pages, 1158 KiB  
Communication
Convenient Synthesis of Triphenylphosphine Sulfide from Sulfur and Triphenylphosphine
by Thanh Binh Nguyen
Clean Technol. 2022, 4(2), 234-238; https://doi.org/10.3390/cleantechnol4020013 - 22 Mar 2022
Cited by 5 | Viewed by 5484
Abstract
Elemental sulfur (S8) was found to react very rapidly (<1 min) with a stoichiometric amount of triphenylphosphine at rt in sufficient amount of solvent (0.2–0.5 mL of solvent/1 mmol of PPh3). Compared to the previously described methods, the present [...] Read more.
Elemental sulfur (S8) was found to react very rapidly (<1 min) with a stoichiometric amount of triphenylphosphine at rt in sufficient amount of solvent (0.2–0.5 mL of solvent/1 mmol of PPh3). Compared to the previously described methods, the present procedure constitute excellent access to triphenylphosphine sulfide. Full article
(This article belongs to the Special Issue Green Process Engineering)
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16 pages, 3856 KiB  
Article
Study of Influential Parameters of the Caffeine Extraction from Spent Coffee Grounds: From Brewing Coffee Method to the Waste Treatment Conditions
by Alexandre Vandeponseele, Micheline Draye, Christine Piot and Gregory Chatel
Clean Technol. 2021, 3(2), 335-350; https://doi.org/10.3390/cleantechnol3020019 - 2 Apr 2021
Cited by 35 | Viewed by 17858
Abstract
This article aims to study the interest of spent coffee grounds (SCG) valorization through caffeine recovery. In an original way, this study takes into account all the parameters such as (i) the brewing coffee methods (household, coffee shops, etc.); (ii) the storage conditions, [...] Read more.
This article aims to study the interest of spent coffee grounds (SCG) valorization through caffeine recovery. In an original way, this study takes into account all the parameters such as (i) the brewing coffee methods (household, coffee shops, etc.); (ii) the storage conditions, in particular the drying step; (iii) the solid/liquid extraction parameters such as the nature of solvent, the temperature, the extraction time and the solid/liquid ratio; and (iv) the liquid/liquid purification parameters such as the nature, the volume and the pH of extraction medium. Results have shown that spent coffee grounds from coffee-shops obtained by percolation contain a higher amount of caffeine than spent coffee grounds from households obtained from spent pods or filters. A drying treatment is not required when extraction is performed under one week after the spent coffee grounds collection with 96.4% of not degraded caffeine. Solid/liquid extraction performed with 25 mL.g−1 SCG of hydroalcoholic solvent (water/EtOH, v/v 60/40) at 60 °C during 15 min have given a caffeine yield up to 4.67 mg.g−1 SCG. When using ethyl acetate, 93.4% of the caffeine has been selectively recovered by liquid/liquid extraction. Finally, the extraction of caffeine for the valorization of spent coffee grounds is a promising and easy way, which fits with an already important and well established market. Full article
(This article belongs to the Special Issue Green Process Engineering)
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11 pages, 4107 KiB  
Article
Facile Elaboration of Wet Cellulose Film as Catalyst Support of MnOx Nanoparticles for the Catalytic Oxidation of Dyes in Absence of Light
by Larissa V. F. Oliveira, Lionel Limousy, Simona Bennici, Ludovic Josien, Samar Hajjar-Garreau, Mary-Lorène Goddard, Marcos A. Bizeto and Fernanda F. Camilo
Clean Technol. 2021, 3(2), 288-298; https://doi.org/10.3390/cleantechnol3020016 - 31 Mar 2021
Cited by 3 | Viewed by 2930
Abstract
In the present work a remarkably simple procedure for the elaboration of wet cellulose film containing manganese oxide nanoparticles was developed. The films were produced using a mold made by 3D printing using cellulose dissolved in an ionic liquid, which allows the production [...] Read more.
In the present work a remarkably simple procedure for the elaboration of wet cellulose film containing manganese oxide nanoparticles was developed. The films were produced using a mold made by 3D printing using cellulose dissolved in an ionic liquid, which allows the production of thin and homogeneous films of different shapes, types and designs which cannot be made using conventional techniques. Thanks to this possibility, the final catalytic object can be implemented in specific reactors. Manganese oxide nanoparticles were prepared as a colloidal solution by a redox/sol-gel procedure and then deposited on the cellulose films by wet impregnation. The catalytic film obtained was tested in the decomposition of a dye, indigo carmine (IC), in the absence of light. The influence of the pH of the solution on the decomposition rate was investigated. IC total decomposition was measured after 1-h reaction at pH below 3. At pH = 2, no deactivation of the catalyst was observed even after four decomposition cycles. This work provides a new strategy to design cellulose-based catalysts for dye removal from wastewater. Full article
(This article belongs to the Special Issue Green Process Engineering)
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18 pages, 1836 KiB  
Article
Kolbe Electrolysis for the Conversion of Carboxylic Acids to Valuable Products—A Process Design Study
by Daniel Klüh, Wolfgang Waldmüller and Matthias Gaderer
Clean Technol. 2021, 3(1), 1-18; https://doi.org/10.3390/cleantechnol3010001 - 2 Jan 2021
Cited by 27 | Viewed by 10145
Abstract
The substitution of fossil resources by renewable alternatives is a major challenge for our society. Kolbe electrolysis converts carboxylic acids to hydrocarbons, which can be used as base chemicals, specialty chemicals, or fuels. Carboxylic acids may be retrieved from biomass or residues and, [...] Read more.
The substitution of fossil resources by renewable alternatives is a major challenge for our society. Kolbe electrolysis converts carboxylic acids to hydrocarbons, which can be used as base chemicals, specialty chemicals, or fuels. Carboxylic acids may be retrieved from biomass or residues and, in consequence, can be a sustainable feedstock. Since the Kolbe electrolysis has only been investigated in lab scale, this work proposes the first basic engineering design study on process development for a continuously working process. Thermophysical data, including solubility and boiling point, are used to gain insight into requirements on process equipment such as separation processes or process parameters such as operating temperature. Furthermore, Aspen Plus was used to retrieve information on acid base equilibria and azeotropes. The process development for three different feedstocks (acetic acid, valeric acid and lauric acid) was performed. The process design shows that most of the process units are rather straightforward and rely on state of the art technologies. The addition of an alkaline catalyst improves the solubility and deprotonation of the carboxylic acid but on the cost of a possibly lower product selectivity. Elevation of the operating temperature above the Krafft point is necessary for long-chain fatty acids. Kolbe electrolysis can be an interesting technology for future production processes based on carboxylic acids and electricity from sustainable sources. Full article
(This article belongs to the Special Issue Green Process Engineering)
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16 pages, 4613 KiB  
Article
Development of a Low-Cost Experimental Procedure for the Production of Laboratory Samples of Torrefied Biomass
by Leonel J. R. Nunes, Jorge M. C. Ribeiro, Letícia C. R. Sá, Liliana M. E. F. Loureiro, Radu Godina and João C. O. Matias
Clean Technol. 2020, 2(4), 406-421; https://doi.org/10.3390/cleantechnol2040025 - 6 Oct 2020
Cited by 2 | Viewed by 3307
Abstract
Currently, the search for alternative sources of energy is not only due to the scarcity of non-renewable sources, since these still have an availability capable of meeting actual consumption needs, but also due to the negative environmental impacts that its consumption presents. Thus, [...] Read more.
Currently, the search for alternative sources of energy is not only due to the scarcity of non-renewable sources, since these still have an availability capable of meeting actual consumption needs, but also due to the negative environmental impacts that its consumption presents. Thus, the use of biomass as a renewable and sustainable energy source is increasingly presented as an alternative that must be taken into account. Torrefaction is a conversion process that aims to improve the properties of biomass through its thermal decomposition at temperatures between 220 and 320 °C. Torrefaction can be defined by several variables, which have an impact on the final quality of the torrefied biomass. Therefore, there is an increase in the number of studies involving this topic, in order to improve the production of biomass and its use as a renewable energy source, in addition to reducing the costs of this process. In this work, a protocol was developed for a laboratory test procedure to produce low-cost torrefied biomass samples using equipment that can present a cost reduction of around 90%. The samples were analyzed to prove the viability of the developed protocol. The results obtained agree with the current literature, also confirming the improvement of the biomass properties. This work can serve as a platform for the development of other technologies, such as gasification for the production of hydrogen from torrefied biomass. Full article
(This article belongs to the Special Issue Green Process Engineering)
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15 pages, 1105 KiB  
Article
Waste Recovery through Thermochemical Conversion Technologies: A Case Study with Several Portuguese Agroforestry By-Products
by Leonel J. R. Nunes, Liliana M. E. F. Loureiro, Letícia C. R. Sá and Hugo F. C. Silva
Clean Technol. 2020, 2(3), 377-391; https://doi.org/10.3390/cleantechnol2030023 - 10 Sep 2020
Cited by 11 | Viewed by 3231
Abstract
Agroforestry waste stores a considerable amount of energy that can be used. Portugal has great potential to produce bioenergy. The waste generated during agricultural production and forestry operation processes can be used for energy generation, and it can be used either in the [...] Read more.
Agroforestry waste stores a considerable amount of energy that can be used. Portugal has great potential to produce bioenergy. The waste generated during agricultural production and forestry operation processes can be used for energy generation, and it can be used either in the form in which it is collected, or it can be processed using thermochemical conversion technologies, such as torrefaction. This work aimed to characterize the properties of a set of residues from agroforestry activities, namely rice husk, almond husk, kiwi pruning, vine pruning, olive pomace, and pine woodchips. To characterize the different materials, both as-collected and after being subjected to a torrefaction process at 300 °C, thermogravimetric analyses were carried out to determine the moisture content, ash content, fixed carbon content, and the content of volatile substances; elementary analyses were performed to determine the levels of carbon, nitrogen, hydrogen, and oxygen, and the high and low heating values were determined. With these assumptions, it was observed that each form of residual biomass had different characteristics, which are important to know when adapting to conversion technology, and they also had different degrees of efficiency, that is, the amount of energy generated and potentially used when analyzing all factors. Full article
(This article belongs to the Special Issue Green Process Engineering)
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21 pages, 1542 KiB  
Article
Torrefied Biomass as an Alternative in Coal-Fueled Power Plants: A Case Study on Grindability of Agroforestry Waste Forms
by Leonel J. R. Nunes
Clean Technol. 2020, 2(3), 270-289; https://doi.org/10.3390/cleantechnol2030018 - 20 Jul 2020
Cited by 24 | Viewed by 4287
Abstract
The use of biomass as a renewable energy source is currently a reality, mainly due to the role it can play in replacing fossil energy sources. Within this possibility, coal substitution in the production of electric energy presents itself as a strong alternative [...] Read more.
The use of biomass as a renewable energy source is currently a reality, mainly due to the role it can play in replacing fossil energy sources. Within this possibility, coal substitution in the production of electric energy presents itself as a strong alternative with high potential, mostly due to the possibility of contributing to the decarbonization of energy production while, at the same time, contributing to the circularization of energy generation processes. This can be achieved through the use of biomass waste forms, which have undergone a process of improving their properties, such as torrefaction. However, for this to be viable, it is necessary that the biomass has a set of characteristics similar to those of coal, such that its use may occur in previously installed systems. In particular, with respect to grindability, which is associated with one of the core equipment technologies of coal-fired power plants—the coal mill. The objective of the present study is to determine the potential of certain residues with agroforestry origins as a replacement for coal in power generation by using empirical methods. Selected materials—namely, almond shells, kiwifruit pruning, vine pruning, olive pomace, pine woodchips, and eucalyptus woodchips—are characterized in this regard. The materials were characterized in the laboratory and submitted to a torrefaction process at 300 °C. Then, the Statistical Grindability Index and the Hardgrove Grindability Index were determined, using empirical methods derived from coal analysis. The results obtained indicate the good potential of the studied biomasses for use in large-scale torrefaction processes and as replacements for coal in the generation of electrical energy. However, further tests are still needed, particularly relating to the definition of the ideal parameters of the torrefaction process, in order to optimize the grindability of the materials. Full article
(This article belongs to the Special Issue Green Process Engineering)
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20 pages, 3459 KiB  
Article
Electroreforming of Glucose and Xylose in Alkaline Medium at Carbon Supported Alloyed Pd3Au7 Nanocatalysts: Effect of Aldose Concentration and Electrolysis Cell Voltage
by Thibault Rafaïdeen, Neha Neha, Bitty Roméo Serge Kouamé, Stève Baranton and Christophe Coutanceau
Clean Technol. 2020, 2(2), 184-203; https://doi.org/10.3390/cleantechnol2020013 - 16 Jun 2020
Cited by 10 | Viewed by 3885
Abstract
The effects of cell voltage and of concentration of sugars (glucose and xylose) on the performances of their electro-reforming have been evaluated at a Pd3Au7/C anode in 0.10 mol L−1 NaOH solution. The catalyst synthesized by a wet [...] Read more.
The effects of cell voltage and of concentration of sugars (glucose and xylose) on the performances of their electro-reforming have been evaluated at a Pd3Au7/C anode in 0.10 mol L−1 NaOH solution. The catalyst synthesized by a wet chemistry route is first comprehensively characterized by physicochemical and electrochemical techniques. The supported catalyst consists in alloyed Pd3Au7 nanoparticles of circa 6 nm mean diameter deposited on a Vulcan XC72 carbon support, with a metal loading close to 40 wt%. Six-hour chronoamperometry measurements are performed at 293 K in a 25 cm2 electrolysis cell for the electro-conversion of 0.10 mol L−1 and 0.50 mol L−1 glucose and xylose at cell voltages of +0.4 V, +0.6 V and +0.8 V. Reaction products are analyzed every hour by high performance liquid chromatography. The main products are gluconate and xylonate for glucose and xylose electro-reforming, respectively, but the faradaic yield, the selectivity and the formation rate of gluconate/xylonate decrease with the increase of aldose concentration, whereas lower faradaic yields and higher formation rates of gluconate/xylonate are observed at +0.8 V than at +0.4 V (higher chemical yields). Full article
(This article belongs to the Special Issue Green Process Engineering)
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Review

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17 pages, 9756 KiB  
Review
Renewable Biomass Utilization: A Way Forward to Establish Sustainable Chemical and Processing Industries
by Yadhu N. Guragain and Praveen V. Vadlani
Clean Technol. 2021, 3(1), 243-259; https://doi.org/10.3390/cleantechnol3010014 - 17 Mar 2021
Cited by 27 | Viewed by 4749
Abstract
Lignocellulosic biomass feedstocks are promising alternatives to fossil fuels for meeting raw material needs of processing industries and helping transit from a linear to a circular economy and thereby meet the global sustainability criteria. The sugar platform route in the biochemical conversion process [...] Read more.
Lignocellulosic biomass feedstocks are promising alternatives to fossil fuels for meeting raw material needs of processing industries and helping transit from a linear to a circular economy and thereby meet the global sustainability criteria. The sugar platform route in the biochemical conversion process is one of the promising and extensively studied methods, which consists of four major conversion steps: pretreatment, hydrolysis, fermentation, and product purification. Each of these conversion steps has multiple challenges. Among them, the challenges associated with the pretreatment are the most significant for the overall process because this is the most expensive step in the sugar platform route and it significantly affects the efficiency of all subsequent steps on the sustainable valorization of each biomass component. However, the development of a universal pretreatment method to cater to all types of feedstock is nearly impossible due to the substantial variations in compositions and structures of biopolymers among these feedstocks. In this review, we have discussed some promising pretreatment methods, their processing and chemicals requirements, and the effect of biomass composition on deconstruction efficiencies. In addition, the global biomass resources availability and process intensification ideas for the lignocellulosic-based chemical industry have been discussed from a circularity and sustainability standpoint. Full article
(This article belongs to the Special Issue Green Process Engineering)
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16 pages, 1422 KiB  
Review
Solvolysis of Kraft Lignin to Bio-Oil: A Critical Review
by Abraham Castro Garcia, Shuo Cheng and Jeffrey S. Cross
Clean Technol. 2020, 2(4), 513-528; https://doi.org/10.3390/cleantechnol2040032 - 14 Dec 2020
Cited by 16 | Viewed by 5711
Abstract
Lignin, a component of lignocellulosic biomass, is abundant and is produced extensively as a waste product of the Kraft pulping process, lignin obtained from this process is called Kraft lignin (KL). Lignin’s three-dimensional structure composed of aromatic alcohols (monolignols) makes it a potential [...] Read more.
Lignin, a component of lignocellulosic biomass, is abundant and is produced extensively as a waste product of the Kraft pulping process, lignin obtained from this process is called Kraft lignin (KL). Lignin’s three-dimensional structure composed of aromatic alcohols (monolignols) makes it a potential source of renewable aromatic chemicals or bio-oil, if depolymerized. Among all the depolymerization methods for KL, solvolysis is the most popular, showing consistently high bio-oil yields. Despite the large number of studies that have been carried out, an economically feasible industrial process has not been found and comparison among the various studies is difficult, as very different studies in terms of reaction media and catalysts report seemingly satisfactory results. In this review, we compare and analyze KL solvolysis studies published, identify trends in bio-oil composition and give a comprehensive explanation about the mechanisms involved in the processes. Additional commentary is offered about the availability and future potential of KL as a renewable feedstock for aromatic chemicals, as well as logistical and technical aspects. Full article
(This article belongs to the Special Issue Green Process Engineering)
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25 pages, 600 KiB  
Review
Lignocellulosic Biomass Mild Alkaline Fractionation and Resulting Extract Purification Processes: Conditions, Yields, and Purities
by Vincent Oriez, Jérôme Peydecastaing and Pierre-Yves Pontalier
Clean Technol. 2020, 2(1), 91-115; https://doi.org/10.3390/cleantechnol2010007 - 14 Feb 2020
Cited by 51 | Viewed by 7036
Abstract
Fractionation of lignocellulose is a fundamental step in the valorization of cellulose, hemicelluloses, and lignin to produce various sustainable fuels, materials and chemicals. Strong alkaline fractionation is one of the most applied processes since the paper industry has been using it for more [...] Read more.
Fractionation of lignocellulose is a fundamental step in the valorization of cellulose, hemicelluloses, and lignin to produce various sustainable fuels, materials and chemicals. Strong alkaline fractionation is one of the most applied processes since the paper industry has been using it for more than a century, and the mineral acid fractionation process is currently the most applied for the production of cellulosic ethanol. However, in the last decade, mild alkaline fractionation has been becoming increasingly widespread in the frame of cellulosic ethanol biorefineries. It leads to the solubilization of hemicelluloses and lignin at various extent depending on the conditions of the extraction, whereas the cellulose remains insoluble. Some studies showed that the cellulose saccharification and fermentation into ethanol gave higher yields than the mineral acid fractionation process. Besides, contrary to the acid fractionation process, the mild alkaline fractionation process does not hydrolyze the sugar polymers, which can be of interest for different applications. Lignocellulosic mild alkaline extracts contain hemicelluloses, lignin oligomers, phenolic monomers, acetic acid, and inorganic salts. In order to optimize the economic efficiency of the biorefineries using a mild alkaline fractionation process, the purification of the alkaline extract to valorize its different components is of major importance. This review details the conditions used for the mild alkaline fractionation process and the purification techniques that have been carried out on the obtained hydrolysates, with a focus on the yields and purities of the different compounds. Full article
(This article belongs to the Special Issue Green Process Engineering)
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