| 1. |
- Abdelhamid, Hani Nasser, 1986-, et al.
(author)
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Cellulose-Based Materials for Water Remediation : Adsorption, Catalysis, and Antifouling
- 2021
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 3
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Research review (peer-reviewed)abstract
- Cellulose-based materials have been advanced technologies that used in water remediation. They exhibit several advantages being the most abundant biopolymer in nature, high biocompatibility, and contain several functional groups. Cellulose can be prepared in several derivatives including nanomaterials such as cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibrils (TOCNF). The presence of functional groups such as carboxylic and hydroxyls groups can be modified or grafted with organic moieties offering extra functional groups customizing for specific applications. These functional groups ensure the capability of cellulose biopolymers to be modified with nanoparticles such as metal-organic frameworks (MOFs), graphene oxide (GO), silver (Ag) nanoparticles, and zinc oxide (ZnO) nanoparticles. Thus, they can be applied for water remediation via removing water pollutants including heavy metal ions, organic dyes, drugs, and microbial species. Cellulose-based materials can be also used for removing microorganisms being active as membranes or antibacterial agents. They can proceed into various forms such as membranes, sheets, papers, foams, aerogels, and filters. This review summarized the applications of cellulose-based materials for water remediation via methods such as adsorption, catalysis, and antifouling. The high performance of cellulose-based materials as well as their simple processing methods ensure the high potential for water remediation.
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| 2. |
- Aristizábal-Lanza, Lucía, et al.
(author)
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Comparison of the enzymatic depolymerization of polyethylene terephthalate and AkestraTM using Humicola insolens cutinase
- 2022
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 4
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Journal article (peer-reviewed)abstract
- The enzymatic depolymerization of synthetic polyesters has become of great interest in recycling plastics. Most of the research in this area focuses on the depolymerization of polyethylene terephthalate (PET) due to its widespread use in various applications. However, the enzymatic activity on other commercial polyesters is less frequently investigated. Therefore, AkestraTM attracted our attention, which is a copolymer derived from PET with a partially biobased spirocyclic acetal structure. In this study, the activity of Humicola insolens cutinase (HiCut) on PET and AkestraTM films and powder was investigated. HiCut showed higher depolymerization activity on amorphous PET films than on Akestra™ films. However, an outstanding performance was achieved on AkestraTM powder, reaching 38% depolymerization in 235h, while only 12% for PET powder. These results are consistent with the dependence of the enzymes on the crystallinity of the polymer since Akestra™ is amorphous while the PET powder has 14% crystallinity. On the other hand, HiCut docking studies and molecular dynamic simulations (MD) suggested that the PET-derived mono (hydroxyethyl)terephthalate dimer (MHET)2 is a hydrolyzable ligand, producing terephthalic acid (TPA), while the Akestra™-derived TPA-spiroglycol ester is not, which is consistent with the depolymerization products determined experimentally. MD studies also suggest ligand-induced local conformational changes in the active site.
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| 3. |
- Biermann, Max, 1989, et al.
(author)
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Carbon Allocation in Multi-Product Steel Mills That Co‐process Biogenic and Fossil Feedstocks and Adopt Carbon Capture Utilization and Storage Technologies
- 2020
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 2
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Journal article (peer-reviewed)abstract
- This work investigates the effects of carbon allocation on the emission intensities of low-carbon products cogenerated in facilities that co‐process biogenic and fossil feedstocks and apply the carbon capture utilization and storage technology. Thus, these plants simultaneously sequester CO2 and synthesize fuels or chemicals. We consider an integrated steel mill that injects biomass into the blast furnace, captures CO2 for storage, and ferments CO into ethanol from the blast furnace gas. We examine two schemes to allocate the CO2 emissions avoided [due to the renewable feedstock share (biomass) and CO2 capture and storage (CCS)] to the products of steel, ethanol, and electricity (generated through the combustion of steel mill waste gases): 1) allocation by (carbon) mass, which represents actual carbon flows, and 2) a free-choice attribution that maximizes the renewable content allocated to electricity and ethanol. With respect to the chosen assumptions on process performance and heat integration, we find that allocation by mass favors steel and is unlikely to yield an ethanol product that fulfills the Renewable Energy Directive (RED) biofuel criterion (65% emission reduction relative to a fossil comparator), even when using renewable electricity and applying CCS to the blast furnace gas prior to CO conversion into ethanol and electricity. In contrast, attribution fulfills the criterion and yields bioethanol for electricity grid intensities 2/kWhel without CCS and yields bioethanol for grid intensities up to 800 gCO2/kWhel with CCS. The overall emissions savings are up to 27 and 47% in the near-term and long-term future, respectively. The choice of the allocation scheme greatly affects the emissions intensities of cogenerated products. Thus, the set of valid allocation schemes determines the extent of flexibility that manufacturers have in producing low-carbon products, which is relevant for industries whose product target sectors that value emissions differently. We recommend that policymakers consider the emerging relevance of co‐processing in nonrefining facilities. Provided there is no double-accounting of emissions, policies should contain a reasonable degree of freedom in the allocation of emissions savings to low-carbon products, so as to promote the sale of these savings, thereby making investments in mitigation technologies more attractive to stakeholders.
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| 4. |
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| 5. |
- Marton, Sofie, 1988, et al.
(author)
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Costs vs. Flexibility of Process Heat Recovery Solutions Considering Short-Term Process Variability and Uncertain Long-Term Development
- 2021
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 3
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Journal article (peer-reviewed)abstract
- To significantly decrease fossil carbon emissions from oil refineries, a combination of climate mitigation options will be necessary, with potential options including energy efficiency, carbon capture and storage/utilization, biomass integration and electrification. Since existing refinery processes as well as many of the potential new processes are characterized by large heating demands, but also offer large opportunities for process excess heat recovery, heat integration plays a major role for energy efficient refinery operation after the implementation of such measures. Consequently, the process heat recovery systems should not only be able to handle current operating conditions, but also allow for flexibility towards possible future developments. Evaluation of the flexibility of process heat recovery measures with both these perspectives enables a more accurate screening and selection of alternative process design options. This paper proposes a new approach for assessing the trade-off between total annual cost and potential operating flexibility for the heat exchanger network in short-as well as in long-term perspectives. The flexibility assessment is based on the evaluation of a flexibility ratio (similar to the conventional flexibility index) to determine the range in which operating conditions may vary while at the same time achieving feasible operation. The method is further based on identification of critical operating points to achieve pre-defined flexibility targets. This is followed by optimization of design properties (i.e., heat exchanger areas) such that feasible operation is ensured in the critical operating points and costs are minimized for representative operating conditions. The procedure is repeated for a range of different flexibility targets, resulting in a curve that shows the costs as a function of desired flexibility ratio. The approach is illustrated by an example representing a heat exchanger network retrofit at a large oil refinery. Finally, the paper illustrates a way to evaluate the cost penalty if the retrofit is optimized for one operating point but then operated under changed conditions. Consequently, the presented approach provides knowledge about cost and flexibility towards short-term variations considering also changes in operating conditions due to long-term development.
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| 6. |
- Muratovska, Nina, et al.
(author)
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Recombinant yeast for production of the pain receptor modulator nonivamide from vanillin
- 2023
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 4
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Journal article (peer-reviewed)abstract
- We report on the development of a method based on recombinant yeast Saccharomyces cerevisiae to produce nonivamide, a capsaicinoid and potent agonist of the pain receptor TRPV1. Nonivamide was produced in a two-step batch process where yeast was i) grown aerobically on glucose and ii) used to produce nonivamide from vanillin and non-anoic acid by bioconversion. The yeast was engineered to express multiple copies of an amine transaminase from Chromobacterium violaceum (CvTA), along with an NADH-dependent alanine dehydrogenase from Bacillus subtilis (BsAlaDH) to enable efficient reductive amination of vanillin. Oxygen-limited conditions and the use of ethanol as a co-substrate to regenerate NADH were identified to favour amination over the formation of the by-products vanillic alcohol and vanillic acid. The native alcohol dehydrogenase ADH6 was deleted to further reduce the formation of vanillic alcohol. A two-enzyme system consisting of an N-acyltransferase from Capsicum annuum (CaAT), and a CoA ligase from Sphingomonas sp. Ibu-2 (IpfF) was co-expressed to produce the amide. This study provides proof of concept for yeast-based production of non-ivamide by combined transamination and amidation of vanillin.
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| 7. |
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| 8. |
- Nypelö, Tiina, 1982, et al.
(author)
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N2O–Assisted Siphon Foaming of Modified Galactoglucomannans With Cellulose Nanofibers
- 2021
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 3:11 November
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Journal article (peer-reviewed)abstract
- Foaming of most bio-based polymers is challenged by low pore formation and foam stability. At the same time, the developing utilization of bio-based materials for the circular economy is placing new demands for easily processable, low-density materials from renewable raw materials. In this work, we investigate cellulose nanofiber (CNF) foams in which foaming is facilitated with wood-based hemicelluloses, galactoglucomannans (GGMs). Interfacial activity of the GGM is modulated via modification of the molecule’s amphiphilicity, where the surface tension is decreased from approximately 70 to 30 mN m−1 for unmodified and modified GGM, respectively. The chemical modification of GGMs by substitution with butyl glycidyl ether increased the molecule’s hydrophobicity and interaction with the nanocellulose component. The highest specific foam volume using 1 wt% CNF was achieved when modified GGM was added (3.1 ml g−1), compared to unmodified GGM with CNF (2.1 ml g−1). An amount of 96 and 98% of the GGM and GGM-BGE foams were lost after 15 min of foaming while the GGM and GGM-BGE with cellulose nanofibers lost only 33 and 28% of the foam respectively. In the case of GGM-BGE, the foam stability increased with increasing nanofiber concentration. This suggests that the altered hydrophobicity facilitated increased foam formation when the additive was incorporated in the CNF suspension and foamed with nitrous oxide (N2O). Thus, the hydrophobic character of the modified GGM was a necessity for foam formation and stability while the CNFs were needed for generating a self-standing foam structure.
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| 9. |
- Shifa, Tofik Ahmed, et al.
(author)
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Controllable Synthesis of 2D Nonlayered Cr2S3 Nanosheets and Their Electrocatalytic Activity Toward Oxygen Evolution Reaction
- 2021
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In: Frontiers in Chemical Engineering. - : Frontiers Media Sa. - 2673-2718. ; 3
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Journal article (peer-reviewed)abstract
- The design of oxygen evolution reaction (OER) electrocatalysts based on Earth-abundant materials holds great promise for realizing practically viable water-splitting systems. In this regard, two-dimensional (2D) nonlayered materials have received considerable attention in recent years owing to their intrinsic dangling bonds which give rise to the exposure of unsaturated active sites. In this work, we solved the synthesis challenge in the development of a 2D nonlayered Cr2S3 catalyst for OER application via introducing a controllable chemical vapor deposition scheme. The as-obtained catalyst exhibits a very good OER activity requiring overpotentials of only 230 mV and 300 mV to deliver current densities of 10 mA cm(-2) and 30 mA cm(-2), respectively, with robust stability. This study provides a general approach to optimize the controllable growth of 2D nonlayered material and opens up a fertile ground for studying the various strategies to enhance the water splitting reactions.
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| 10. |
- Sirigina, Devesh Sathya Sri Sairam, et al.
(author)
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Non-Fossil Methane Emissions Mitigation From Agricultural Sector and Its Impact on Sustainable Development Goals
- 2022
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 4
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Journal article (peer-reviewed)abstract
- The agriculture sector contributes to ∼40% of methane emissions globally. Methane is also 28 times (Assessment Report 5) more potent greenhouse gas than CO2. In this study, we assess the impact of measures for mitigating methane emissions from the agricultural sector on the achievement of all the 17 United Nations’ Sustainable Development Goals (SDGs). A keyword literature review was employed that focused on finding the synergies and trade-offs with non-fossil methane emissions from the agricultural sector and respective SDGs’ targets. The results were in broad consensus with the literature aimed at finding the relationship between SDGs and measures targeting climate change. There is a total of 88 synergies against eight trade-offs from the 126 SDGs’ targets that were assessed. It clearly shows that measures to mitigate methane emissions from the agricultural sector will significantly help in achieving the SDGs. Since agriculture is the primary occupation and the source of income in developing countries, it can further be inferred that methane mitigation measures in developing countries will play a larger role in achieving SDGs. Measures to mitigate methane emissions reduce poverty; diversify the source of income; promote health, equality, education, sanitation, and sustainable development while providing energy and resource security to the future generations.
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| 11. |
- Spirk, Stefan, et al.
(author)
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Current opportunities and challenges in biopolymer thin film analysis–determination of film thickness
- 2021
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 3
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Journal article (other academic/artistic)abstract
- Polymer thin films with thickness below 100 nm are a fascinating class of 2D materials with commercial and research applications in many branches ranging from coatings to photoresists and insulating materials, to mention just a few uses. Biopolymers have extended the scope of polymer thin films with unique materials such as cellulose, cellulose nanocrystals, cellulose nanofibrils with tunable water uptake, crystallinity and optical properties. The key information needed in thin biopolymer film use and research is film thickness. It is often challenging to determine precisely and hence several techniques and their combinations are used. Additional challenges with hydrophilic biopolymers such as cellulose are the presence of humidity and the soft and often heterogenous structure of the films. This minireview summarizes currently used methods and techniques for biopolymer thin film thickness analysis and outlines challenges for accurate and reproducible characterization. Cellulose is chosen as the representative biopolymer.
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| 12. |
- Volpatti, Lisa R., et al.
(author)
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Editorial: Women in chemical engineering
- 2023
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In: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 5
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Journal article (other academic/artistic)
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| 13. |
- Westholm, Lena Johansson, 1967-
(author)
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Filter media for storm water treatment in sustainable cities : A review
- 2023
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In: Frontiers in Chemical Engineering. - : Frontiers Media S.A.. - 2673-2718. ; 5
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Journal article (peer-reviewed)abstract
- Storm water treatment and management will be more important in the future due to climate changes, e.g., more frequent, and intense rain events that might cause flooding. To meet these challenges, low impact development (LID) technologies such as paved surfaces, green roofs and various bioretention systems have been suggested in urban areas. Various filter media, natural and engineered materials, have been used to amend the LID solutions in field experiments enhancing the removal of different contaminants present in storm water of different kinds. Researchers suggest locally available low-cost media having high capacity to remove pollutants. Other parameters to take into consideration when selecting filter media are clogging, hydraulic parameters. Climatic conditions in different regions, e.g., temperate, or cold climatic zones, do not seem to have a large impact on performance on LID solutions.
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