Special Issue "Green Sustainable Chemical Processes"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Chemical Systems".

Deadline for manuscript submissions: 31 October 2019.

Special Issue Editors

Guest Editor
Prof. Dr. Francisco José Hernández Fernández Website E-Mail
Chemical and Environmental Engineering, Technical University of Cartagena, 30202 Cartagena, Spain
Interests: ionic liquid; supercritical fluid; green chemistry; bioenergy; fuel cell
Guest Editor
Prof. Dr. Antonia Pérez de los Ríos Website E-Mail
Department of Chemical Engineering University of Murcia, Campus de Espinardo, 30071 Murcia, Spain
Phone: 0034 868889112
Interests: ionic liquid; green chemistry; membrane technology; fuel cell; biofuel

Special Issue Information

Dear Colleagues,

The present Special Issue will include cutting-edge advances in green sustainable chemical processes. Research in this field is directed towards the development of methods and new chemical engineering routes that can be integrated into industrial processing for safer, more flexible, economic and ecological production processes in the context of green and sustainable chemical engineering.

We invite authors to submit original research and review articles that promote the design and efficient use of environmentally benign chemical processes. We are particularly interested in articles that explore the development of processes that use renewable resources and green solvents, alternative sources of energy, process intensification and innovative environmental technologies for water treatment and pollution control.

Potential topics include, but are not limited to:

  • Renewable resources (valorization of agricultural and industrial waste).
  • Alternative solvents (ionic liquid and supercritical fluids).
  • Biofuels and other alternative sources of energy.
  • Process intensification.
  • Catalysis and biocatalysis.
  • Nanotechnology.
  • Environmental technologies for water treatment and pollution control.
  • Process systems engineering

Prof. Dr. Francisco José Hernández Fernández
Prof. Dr. Antonia Pérez de los Ríos
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. Processes 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 1200 CHF (Swiss Francs). Please note that for papers submitted after 31 December 2019 an APC of 1400 CHF applies. 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 Chemistry
  • Green Engineering
  • Alternative Solvent
  • Renewable Resource
  • Bioenergy
  • Wastewater Treatment
  • Process Intensification
  • Nanotechnology
  • Process Conceptualization

Published Papers (11 papers)

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Research

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Open AccessArticle
Valorization of Swine Manure into Hydrochars
Processes 2019, 7(9), 560; https://doi.org/10.3390/pr7090560 - 23 Aug 2019
Abstract
There is a significant interest in valorizing swine manure that is produced in enormous quantities. Therefore, considering the high moisture content in swine manure, the objective of this research was to convert manure slurry into hydrochars via hydrothermal carbonization and analyze the yields, [...] Read more.
There is a significant interest in valorizing swine manure that is produced in enormous quantities. Therefore, considering the high moisture content in swine manure, the objective of this research was to convert manure slurry into hydrochars via hydrothermal carbonization and analyze the yields, pH, energy contents, and thermal and oxidation kinetic parameters. Experiments were performed in triplicate in 250 mL kettle reactors lined with polypropylene at 180 °C, 200 °C, 240 °C, 220 °C, and 260 °C for 24 h. Analyses of the results indicated that the process temperature affected the hydrochar yields, with yield generally decreasing with increasing temperature, but it had little effect on the composition of the hydrochar. The hydrochars were found to have higher volatile contents and H/C and O/C ratios and about 85% of the energy compared to coal. However, the presence of high fraction (35–38%) of ash in hydrochars is a serious concern and needs to be addressed before the complete utilization of hydrochars as fuels. The surface characterization of hydrochars coupled with wet chemistry experiments indicated that hydrochars were equipped with nitrogen functional groups with points of zero charges between 6.76 and 7.85, making them suitable as adsorbents and soil remediation agents and energy storage devices. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
On the Selective Transport of Nutrients through Polymer Inclusion Membranes Based on Ionic Liquids
Processes 2019, 7(8), 544; https://doi.org/10.3390/pr7080544 - 16 Aug 2019
Abstract
In the last few years, the use of ionic liquid-based membranes has gained importance in a wide variety of separation processes due to the unique properties of ionic liquids. The aim of this work is to analyze the transport of nutrients through polymer [...] Read more.
In the last few years, the use of ionic liquid-based membranes has gained importance in a wide variety of separation processes due to the unique properties of ionic liquids. The aim of this work is to analyze the transport of nutrients through polymer inclusion membranes based on different concentrations of methyltrioctylammonium chloride, in order to broaden the application range of these kinds of membranes. Calcium chloride (CaCl2) and sodium hydrogen phosphate (Na2HPO4) nutrients were used at the concentration of 1 g·L−1 in the feeding phase. The evolution of the concentration in the receiving phase over time (168 h) was monitored and the experimental data fitted to a diffusion-solution transport model. The results show very low permeation values for CaCl2. By contrast, in the case of Na2HPO4 the permeation values were higher and increase as the amount of ionic liquid in the membrane also increases. The surface of the membranes was characterized before and after being used in the separation process by scanning electron microscopy coupled to energy dispersive X-Ray spectroscopy (SEM–EDX) and elemental mapping analysis. The SEM–EDX images show that the polymer inclusion membranes studied are stable to aqueous solution contacting phases and therefore, they might be used for the selective transport of nutrients in separation processes. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Determination of the Potential Impact of Domestic Anaerobic Digester Systems: A Community Based Research Initiative in Rural Bangladesh
Processes 2019, 7(8), 512; https://doi.org/10.3390/pr7080512 - 05 Aug 2019
Abstract
This research examines the potential impact of domestic anaerobic digester (AD) systems adopted in Bangladesh and similar developing countries. Cattle dung and poultry litter feed stocks were specifically investigated, because these were freely available and plentiful to people living within agricultural areas of [...] Read more.
This research examines the potential impact of domestic anaerobic digester (AD) systems adopted in Bangladesh and similar developing countries. Cattle dung and poultry litter feed stocks were specifically investigated, because these were freely available and plentiful to people living within agricultural areas of rural Bangladesh. Data was collected to ascertain whether these two representative AD facility types provide tangible social, economic and environmental impact that benefits homeowners. Primary quantitative and qualitative data was obtained by field data collection, and meeting with expert groups and stakeholders. Empirical analysis conducted revealed that variations were found in the biomass feedstocks available on different sites but also differences were apparent in terms of the operations and maintenance (O and M) systems of the biogas plants operated. The biogas and methane yield variation was also measured, and variations were found in the cattle dung and poultry litter AD yield capacity. Overall, 64% of feedstock was utilised, 91% of biogas plants remain underfed and energy yield efficiency was 57% from cattle smallholdings’ AD and 28% from poultry farms’ AD. These results showed that small scale AD can offer a significant impact upon rural lifestyles through augmented economics, improved social activities, relationship building with neighbours and improved lifestyle achieved via time savings accrued. These results could help rural entrepreneurs, AD equipment providers and government institutions to develop a road map to implement future AD installation on a much wider geographical scale. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Natural Deep Eutectic Solvent-Assisted Pectin Extraction from Pomelo Peel Using Sonoreactor: Experimental Optimization Approach
Processes 2019, 7(7), 416; https://doi.org/10.3390/pr7070416 - 02 Jul 2019
Abstract
Background: Natural deep eutectic solvents (NADESs) can be used for extracting a wide range of biomaterials, such as pectin. This study introduces a new generation of natural solvents for pectin extraction which could replace the conventional solvents in the food industry. Methods: In [...] Read more.
Background: Natural deep eutectic solvents (NADESs) can be used for extracting a wide range of biomaterials, such as pectin. This study introduces a new generation of natural solvents for pectin extraction which could replace the conventional solvents in the food industry. Methods: In this study, NADESs were used for pectin extraction from pomelo (Citrus grandis (L.) Osbeck) peels using a sonoreactor. Definitive screening design (DSD) was used to screen the influence of time, temperature, solid/liquid ratio, and NADES/water ratio on the pectin yield and degree of esterification (DE). Results: The primary screening revealed that the best choices for the extraction were choline chloride–malonic acid (ChCl-Mal) and choline chloride–glucose–water (ChCl:Glc:W). Both co-solvents yielded 94% pectin and 52% DE after optimization at 80 °C, with 60 min of sonication, pH < 3.0, and a NADES-to-water ratio of 1:4.5 (v/v). Morphological screening showed a smooth and compact surface of the pectin from ChCl-Mal where glucose-based pectin had a rough surface and lower DE. Conclusions: NADESs proved to be promising co-solvents for pectin extraction with a high degree of esterification (>55%). Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Kinetics of Arsenic Removal in Waste Acid by the Combination of CuSO4 and Zero-Valent Iron
Processes 2019, 7(7), 401; https://doi.org/10.3390/pr7070401 - 28 Jun 2019
Abstract
In this study, we investigated the kinetics of arsenic removal from waste acid by the combination of zero-valent iron (ZVI) and CuSO4. ZVI samples were characterized by X-ray diffraction and scanning electron microscopy before and after arsenic removal; the results showed [...] Read more.
In this study, we investigated the kinetics of arsenic removal from waste acid by the combination of zero-valent iron (ZVI) and CuSO4. ZVI samples were characterized by X-ray diffraction and scanning electron microscopy before and after arsenic removal; the results showed that after the arsenic removal reaction, As2O3 and magnetite phases were detected on the surface of these samples. Kinetic studies were carried out under different reaction temperatures, with different CuSO4 concentrations, and with different iron to arsenic molar ratios (Fe/As). The kinetic data of the arsenic removal were fitted to different kinetic models. The fitting results showed that the arsenic removal process could be described by the shrinking core model, controlled by residual layer diffusion. The apparent activation energy of the reaction was 9.0628 kJ/mol, the reaction order with the CuSO4 concentrations was −0.12681, and the reaction order with the molar ratio of iron to arsenic (Fe/As) was 3.152. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Evaluation of the Methane Production Potential of Catfish Processing Wastewater Using Various Anaerobic Digestion Strategies
Processes 2019, 7(6), 368; https://doi.org/10.3390/pr7060368 - 12 Jun 2019
Abstract
The U.S. catfish industry is a major industry that has been declining over the years due to imports competition and growing operational costs. Catfish processing wastewater management and high energy requirement put a large financial burden on catfish processing facilities. Recovered protein-based solids [...] Read more.
The U.S. catfish industry is a major industry that has been declining over the years due to imports competition and growing operational costs. Catfish processing wastewater management and high energy requirement put a large financial burden on catfish processing facilities. Recovered protein-based solids have provided some value-added co-products, however, more co-products are needed to offset processing costs. Anaerobic digestion is a proven waste treatment method that produces methane, which is an energetic co-product that can be used within the processing facilities. This study was conducted to evaluate the potential of anaerobic digestion as an alternative to the currently used aerobic biotreatment of catfish processing wastewater. Initial assessments indicated the recalcitrance of the full-strength wastewater to anaerobic digestion, yielding only ~4 m3 per ton (U.S.) of input chemical oxygen demand (CODinput). Thus, several strategies were evaluated to improve the methane yield from the wastewater. These strategies include nutrient (nitrogen and sulfur) amendment, along with ozone, HCl, and NaOH pretreatment. The results showed that nutrient amendment was the most suitable strategy for improving the digestibility of the catfish processing wastewater. A methane yield of 121–236 m3/ton (U.S.) CODinput was obtained, with a purity of 67–80 vol.%. These results are similar to yields and purities of biogas from other feedstock, such as food waste, wastewater solids, and fish canning wastewater. This indicates that anaerobic digestion could be a viable alternative for simultaneous treatment and energetic co-product generation from catfish processing wastewater. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Prediction of CO2 Solubility in Ionic Liquids Based on Multi-Model Fusion Method
Processes 2019, 7(5), 258; https://doi.org/10.3390/pr7050258 - 03 May 2019
Abstract
Reducing the emissions of greenhouse gas is a worldwide problem that needs to be solved urgently for sustainable development in the future. The solubility of CO2 in ionic liquids is one of the important basic data for capturing CO2. Considering [...] Read more.
Reducing the emissions of greenhouse gas is a worldwide problem that needs to be solved urgently for sustainable development in the future. The solubility of CO2 in ionic liquids is one of the important basic data for capturing CO2. Considering the disadvantages of experimental measurements, e.g., time-consuming and expensive, the complex parameters of mechanism modeling and the poor stability of single data-driven modeling, a multi-model fusion modeling method is proposed in order to predict the solubility of CO2 in ionic liquids. The multiple sub-models are built by the training set. The sub-models with better performance are selected through the validation set. Then, linear fusion models are established by minimizing the sum of squares of the error and information entropy method respectively. Finally, the performance of the fusion model is verified by the test set. The results showed that the prediction effect of the linear fusion models is better than that of the other three optimal sub-models. The prediction effect of the linear fusion model based on information entropy method is better than that of the least square error method. Through the research work, an effective and feasible modeling method is provided for accurately predicting the solubility of CO2 in ionic liquids. It can provide important basic conditions for evaluating and screening higher selective ionic liquids. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Characterization of the Primary Sludge from Pharmaceutical Industry Effluents and Final Disposition
Processes 2019, 7(4), 231; https://doi.org/10.3390/pr7040231 - 24 Apr 2019
Cited by 1
Abstract
The generation of large volumes of waste by industrial processes has become an object of study because of the necessity to characterize the composition of residues in order to suggest appropriate treatments and to minimize adverse environmental impacts. We performed analyses of total [...] Read more.
The generation of large volumes of waste by industrial processes has become an object of study because of the necessity to characterize the composition of residues in order to suggest appropriate treatments and to minimize adverse environmental impacts. We performed analyses of total fixed and volatile solids, moisture, and chemical oxygen demand (COD). We found high organic matter content. We also measured physicochemical characteristics, including corrosivity, reactivity, and toxicity. Sewage sludge showed levels of chloride and sodium above the maximum allowed limits. These data suggest the potential for anaerobic digestion as a treatment option for sewage sludge and for its use as a biofertilizer. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Life Cycle Assessment and Economic Analysis of an Innovative Biogas Membrane Reformer for Hydrogen Production
Processes 2019, 7(2), 86; https://doi.org/10.3390/pr7020086 - 08 Feb 2019
Cited by 1
Abstract
This work investigates the environmental and economic performances of a membrane reactor for hydrogen production from raw biogas. Potential benefits of the innovative technology are compared against reference hydrogen production processes based on steam (or autothermal) reforming, water gas shift reactors and a [...] Read more.
This work investigates the environmental and economic performances of a membrane reactor for hydrogen production from raw biogas. Potential benefits of the innovative technology are compared against reference hydrogen production processes based on steam (or autothermal) reforming, water gas shift reactors and a pressure swing adsorption unit. Both biogas produced by landfill and anaerobic digestion are considered to evaluate the impact of biogas composition. Starting from the thermodynamic results, the environmental analysis is carried out using environmental Life cycle assessment (LCA). Results show that the adoption of the membrane reactor increases the system efficiency by more than 20 percentage points with respect to the reference cases. LCA analysis shows that the innovative BIONICO system performs better than reference systems when biogas becomes a limiting factor for hydrogen production to satisfy market demand, as a higher biogas conversion efficiency can potentially substitute more hydrogen produced by fossil fuels (natural gas). However, when biogas is not a limiting factor for hydrogen production, the innovative system can perform either similar or worse than reference systems, as in this case impacts are largely dominated by grid electric energy demand and component use rather than conversion efficiency. Focusing on the economic results, hydrogen production cost shows lower value with respect to the reference cases (4 €/kgH2 vs 4.2 €/kgH2) at the same hydrogen delivery pressure of 20 bar. Between landfill and anaerobic digestion cases, the latter has the lower costs as a consequence of the higher methane content. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Review

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Open AccessReview
Nanoemulsions: Factory for Food, Pharmaceutical and Cosmetics
Processes 2019, 7(9), 617; https://doi.org/10.3390/pr7090617 - 11 Sep 2019
Abstract
Nanotechnology, particularly nanoemulsions (NEs), have gained increasing interest from researchers throughout the years. The small-sized droplet with a high surface area makes NEs important in many industries. In this review article, the components, properties, formation, and applications are summarized. The advantages and disadvantages [...] Read more.
Nanotechnology, particularly nanoemulsions (NEs), have gained increasing interest from researchers throughout the years. The small-sized droplet with a high surface area makes NEs important in many industries. In this review article, the components, properties, formation, and applications are summarized. The advantages and disadvantages are also described in this article. The formation of the nanosized emulsion can be divided into two types: high and low energy methods. In high energy methods, high-pressure homogenization, microfluidization, and ultrasonic emulsification are described thoroughly. Spontaneous emulsification, phase inversion temperature (PIT), phase inversion composition (PIC), and the less known D-phase emulsification (DPE) methods are emphasized in low energy methods. The applications of NEs are described in three main areas which are food, cosmetics, and drug delivery. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessReview
Metabolic Engineering and Fermentation Process Strategies for L-Tryptophan Production by Escherichia coli
Processes 2019, 7(4), 213; https://doi.org/10.3390/pr7040213 - 12 Apr 2019
Cited by 1
Abstract
L-tryptophan is an essential aromatic amino acid that has been widely used in medicine, food, and animal feed. Microbial biosynthesis of L-tryptophan through metabolic engineering approaches represents a sustainable, cost-effective, and environmentally friendly route compared to chemical synthesis. In particular, metabolic pathway engineering [...] Read more.
L-tryptophan is an essential aromatic amino acid that has been widely used in medicine, food, and animal feed. Microbial biosynthesis of L-tryptophan through metabolic engineering approaches represents a sustainable, cost-effective, and environmentally friendly route compared to chemical synthesis. In particular, metabolic pathway engineering allows enhanced product titers by inactivating/blocking the competing pathways, increasing the intracellular level of essential precursors, and overexpressing rate-limiting enzymatic steps. Based on the route of the L-tryptophan biosynthesis pathway, this review presents a systematic and detailed summary of the contemporary metabolic engineering approaches employed for L-tryptophan production. In addition to the engineering of the L-tryptophan biosynthesis pathway, the metabolic engineering modification of carbon source uptake, by-product formation, key regulatory factors, and the polyhydroxybutyrate biosynthesis pathway in L-tryptophan biosynthesis are discussed. Moreover, fermentation bioprocess optimization strategies used for L-tryptophan overproduction are also delineated. Towards the end, the review is wrapped up with the concluding remarks, and future strategies are outlined for the development of a high L-tryptophan production strain. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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