| 1. |
- Anusuyadevi, Prasaanth Ravi, et al.
(author)
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Photoresponsive and Polarization-Sensitive Structural Colors from Cellulose/Liquid Crystal Nanophotonic Structures
- 2021
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In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 33:36, s. 2101519-
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Journal article (peer-reviewed)abstract
- Cellulose nanocrystals (CNCs) possess the ability to form helical periodic structures that generate structural colors. Due to the helicity, such self-assembled cellulose structures preferentially reflect left-handed circularly polarized light of certain colors, while they remain transparent to right-handed circularly polarized light. This study shows that combination with a liquid crystal enables modulation of the optical response to obtain light reflection of both handedness but with reversed spectral profiles. As a result, the nanophotonic systems provide vibrant structural colors that are tunable via the incident light polarization. The results are attributed to the liquid crystal aligning on the CNC/glucose film, to form a birefringent layer that twists the incident light polarization before interaction with the chiral cellulose nanocomposite. Using a photoresponsive liquid crystal, this effect can further be turned off by exposure to UV light, which switches the nematic liquid crystal into a nonbirefringent isotropic phase. The study highlights the potential of hybrid cellulose systems to create self-assembled yet advanced photoresponsive and polarization-tunable nanophotonics.
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| 2. |
- Capezza, Antonio Jose, et al.
(author)
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Greenhouse gas emissions of biobased diapers containing chemically modified protein superabsorbents
- 2023
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 387
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Journal article (peer-reviewed)abstract
- Replacing the current mainly fossil-based, disposable, and non-biodegradable sanitary products with sustainable, functional alternatives is an industry priority. Suggested biobased alternatives require evaluation of their actual impact on greenhouse gas (GHG) emissions. We evaluated GHG emissions of biobased baby diapers as the most consumed sanitary product, using a biodegradable functionalized protein superabsorbent polymer (bioSAP) and compared them with currently used fossil-based counterparts. Assessment of the diapers also included estimated GHG emissions from the production of the biobased components, transport, and end-of-life combustion of these items. It was shown that only a few of the biobased diaper alternatives resulted in lower GHG emissions than commercial diapers containing fossil-based materials. At the same time, it was demonstrated that the production of the bioSAP via chemical modification of a protein raw material is the primary GHG contributor, with 78% of the total emissions. Reduction of the GHG contribution of the bioSAP production was achieved via a proposed recycling route of the functionalization agent, reducing the GHG emissions by 13% than if no recycling was carried out. Overall, we demonstrated that reduced and competitive GHG emissions could be achieved in sanitary articles using biobased materials, thereby contributing to a sanitary industry producing disposable products with less environmental pollution while allowing customers to keep their current consumption patterns.
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| 3. |
- Capezza, Antonio Jose, et al.
(author)
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High Capacity Functionalized Protein Superabsorbents from an Agricultural Co‐Product: A Cradle‐to‐Cradle Approach
- 2020
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In: Advanced Sustainable Systems. - : Wiley. - 2366-7486.
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Journal article (peer-reviewed)abstract
- Synthesis of superabsorbent particles from nontoxic wheat gluten (WG) protein, as an industrial co‐product, is presented. A natural molecular cross‐linker named genipin (a hydrogenated glycoside) is used together with a dianhydride (ethylenediaminetetraacetic EDTAD), to enable the preparation of a material with a network structure capable of swelling up to ≈4000% in water and ≈600% in saline solution. This represents an increase in swelling by over 10 times compared to the already highly absorbing gluten reference material. The carboxylation (using EDTAD) and the cross‐linking of the protein result in a hydrogel with liquid retention capacity as high as 80% of the absorbed water remaining in the WG network on extensive centrifugation, which is higher than that of commercial fossil‐based superabsorbents. The results also show that more polar forms of the reacted genipin are more effectively grafted onto the protein, contributing to the swelling and liquid retention. Microscopy of the materials reveals extensive nanoporosity (300 nm), contributing to rapid capillarity‐driven absorption. The use of proteins from agricultural industries for the fabrication of sustainable protein superabsorbents is herein described as an emerging avenue for the development of the next generation daily‐care products with a minimal environmental impact.
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| 4. |
- Cui, Yuxiao, et al.
(author)
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Achieving carbonized minitablet-shaped structures from lignin : The importance of heating rate on shape
- 2023
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In: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 176, s. 106260-
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Journal article (peer-reviewed)abstract
- Shape-anisotropic building blocks are vital in the creation of hierarchical materials in nature, as it enables directional alignment, property anisotropy and overall functionality improvement in biological materials. Likewise, the performance of carbonized superstructures could potentially be more precisely designed by using anisotropic building blocks. Lignin represents an important and sustainable alternative in the production of carbonized materials, which is due to its abundance and high carbon content (∼60%). However, to expand its utility, for producing carbonized shape-anisotropic materials, adequate synthesis and pyrolysis-protocols are essential. Here, a fractionated and acetylated Kraft lignin was used to successfully self-assemble shape-anisotropic microcapsules. Then a carbonization procedure (slow heating at 0.6 °C min−1), that retained the original shape-anisotropy after carbonization, was developed. The formation mechanism was discussed as a function of the heating rate. The overall strategy was template-free and the attained shape-anisotropies were well-defined and narrow in size distribution. This is a scalable route for achieving shape-anisotropic carbonized building blocks from lignin.
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| 5. |
- Cui, Yuxiao, et al.
(author)
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Hierarchical soot nanoparticle self-assemblies for enhanced performance as sodium-ion battery anodes
- 2022
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:16, s. 9059-9066
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Journal article (peer-reviewed)abstract
- The drawbacks of amorphous hard carbon are its low conductivity and structural instability, due to its large volume change and the occurrence of side reactions with the electrolyte during cycling. Here, we propose a simple and rapid method to address these disadvantages; we used an emulsion solvent-evaporation method to create hierarchically structured microparticles of hard carbon nanoparticles, derived from soot, and multi-walled-carbon-nanotubes at a very low threshold of 2.8 wt%. These shrub-ball like microparticles have well-defined void spaces between different nanostructures of carbon, leading to an increased surface area, lower charge-resistance and side reactions, and higher electronic conductivity for Na+ insertion and de-insertion. They can be slurry cast to assemble Na+ anodes, exhibiting an initial discharge capacity of 713.3 mA h g(-1) and showing long-term stability with 120.8 mA h g(-1) at 500 mA g(-1) after 500 cycles, thus outperforming neat hard carbon nanoparticles by an order of magnitude. Our work shows that hierarchical self-assembly is attractive for increasing the performance of microparticles used for battery production.
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| 6. |
- Cui, Yuxiao, et al.
(author)
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High Value Use of Technical Lignin. Fractionated Lignin Enables Facile Synthesis of Microcapsules with Various Shapes : Hemisphere, Bowl, Mini-tablets, or Spheres with Single Holes
- 2020
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In: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:35, s. 13282-13291
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Journal article (peer-reviewed)abstract
- Anisotropic carbon-rich microcapsule morphologies are of great value in many applications including catalysis, energy storage, biomedicine, and osmosis-triggered drug delivery, due to an observed shape effect. However, high-precision synthesis, to generate large yields of well-defined anisotropic shapes, is generally challenging. Here, we show for the first time that a modified carbon-rich waste-material, a fractionated and acetylated Kraft lignin, enables facile production of large amounts of well-defined "acorn-like" microcapsules with heterogeneous shell thicknesses. This is due to the inherent physicochemical properties of the fractionated lignin at the oil/water (O/W) interface. The acorn-shape is strongly related to two distinct lignin-molecule populations, that phase separate during microcapsule formation. Fine-tuning the post-treatment conditions (pressure or hydrothermal temperature) results in a number of different microcapsule shapes; hemisphere, bowl, mini-tablets, or spheres with single holes. Further chemical modification to their surfaces is also demonstrated. The present study provides a new library of shape-anisotropic carbon-rich building blocks that open new avenues for assembling hierarchical material with a high level of complexity.
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| 7. |
- Cui, Yuxiao, et al.
(author)
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Self-assembled carbon spheres prepared from abundant lignin and urea for photocatalytic and self-propelling applications
- 2021
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In: Carbon Trends. - : Elsevier BV. - 2667-0569. ; 3, s. 100040-
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Journal article (peer-reviewed)abstract
- Lignin is a valuable bio-resource in the manufacturing of carbon-based functional materials, because of its large carbon content (~60%), various phenolic structural units, abundancy and sustainability. Here, we explored its use in photocatalytic and self-propelling applications. First, hydroxyl-abundant lignin-based carbon precursor particles, HCLSs, were produced by hydrothermal carbonization of lignin-based microcapsules (LCs). Then, by heating urea coated HCLSs, carbon spheres with a layer of graphitic carbon nitride (g-C3N4) were produced. The presence of surface available -OH groups on the HCLSs, were critical in the formation mechanism. Under visible-light irradiation, the photocatalytic spheres exhibited enhanced activity (49% of the model pollutant remained after 60 min, at 100 mW cm−2) and possessed a three times higher average removal rate constant compared to that of g-C3N4 powder. The g-C3N4 powder was obtained when heating urea only. Additionally, by introducing a Pt/Pd coating on only one side of the composite spheres, the spheres were made self-propelling in the presence of a fuel (H2O2). This work provides new insights into the preparation principles of lignin-based photocatalytic spheres for effective solar photocatalysis applications.
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| 8. |
- Wei, Xin-Feng, et al.
(author)
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Millions of microplastics released from a biodegradable polymer during biodegradation/enzymatic hydrolysis
- 2022
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 211
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Journal article (peer-reviewed)abstract
- In this article, we show that enzymatic hydrolysis of a biodegradable polyester (poly(e-caprolactone)) by Amano Lipase PS in an aqueous (buffer) environment yielded rapidly an excessive number of microplastic particles; merely 0.1 g of poly(e-caprolactone) film was demonstrated to yield millions of particles. There were also indications of non-enzymatic hydrolysis at the same conditions, but this did not yield any particles within the time frame of the experiment (up to 6 days). Microplastic particles formed had irregular shapes with an average size of around 10 pm, with only a few reaching 60 pm. The formation of microplastic particles resulted from the uneven hydrolysis/erosion rate across the polymer film surface, which led to a rough and undulating surface with ridge, branch, and rod-shaped micro-protruding structures. The consequent detachment and fragmentation of these micro-sized protruding structures resulted in the release of microplastics to the surroundings. Together with microplastics, hydrolysis products such as acidic monomers and oligomers were also released during the enzymatic hydrolysis process, causing a pH decrease in the surrounding liquid. The results suggest that the risk of microplastic pollution from biodegradable plastics is notable despite their biodegradation. Special attention needs to be paid when using and disposing of biodegradable plastics, considering the enormous impact of the paradigm shift towards more biodegradable products on the environment.
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| 9. |
- Yang, Hanmin, et al.
(author)
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Evaluation of Engineered Biochar-Based Catalysts for Syngas Production in a Biomass Pyrolysis and Catalytic Reforming Process
- 2023
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In: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 37, s. 5942-
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Journal article (peer-reviewed)abstract
- Biochar, originating from biomass pyrolysis, has been proven a promising catalyst for tar cracking/reforming with great coke resistance. This work aims to evaluate various engineered biochar-based catalysts on syngas production in a biomass pyrolysis and catalytic reforming process without feeding extra steam. The tested engineered biochar catalysts include physical- and chemical-activated, nitrogen-doped, and nickel-doped biochars. The results illustrated that the syngas yields were comparable when using biochar and activated biochar as catalysts. A relatively high specific surface area (SSA) and a hierarchical porous structure are beneficial for syngas and hydrogen production. A 2 h physical-activated biochar catalyst induced the syngas with the highest H2/CO ratio (1.5). The use of N-doped biochar decreased the syngas yield sharply due to the collapse of the pore structure but obtained syngas with the highest LHVgas (18.5MJ/Nm3). The use of Ni-doped biochar facilitated high syngas and hydrogen yields (78.2 wt % and 26 mmol H2/g-biomass) and improved gas energy conversion efficiency (73%). Its stability and durability test showed a slight decrease in performance after a three-time repetitive use. A future experiment with a longer time is suggested to determine when the catalyst will finally deactivate and how to reduce the catalyst deterioration. © 2023 The Authors.
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| 10. |
- Yang, Hanmin, et al.
(author)
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High-purity syngas production by cascaded catalytic reforming of biomass pyrolysis vapors
- 2022
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In: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 322
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Journal article (peer-reviewed)abstract
- A novel pyrolysis followed by in-line cascaded catalytic reforming process without additional steam was developed to produce high-purity syngas from woody biomass. The key to the proposed process is the construction of a cascaded biochar + NiAl2O4 catalytic reforming process in which biochar acts as a pre-reforming catalyst, and NiAl2O4 acts as a primary reforming catalyst. The large oxygenates in the pyro-vapors are deeply cracked in the biochar layer due to the increased residence time in the hot-biochar bed. The remaining small molecules are then reformed with the autogenerated steam from pyrolysis catalyzed by the reduced Ni0 species in the NiAl2O4 catalyst (NiAlO). The results showed that the yield of syngas for the optimized process was 71.28 wt% (including 44.44 mg-H2/g-biomass and 536.48 mg-CO/g-biomass), and the CO2 yield of the process was only 3 kg-CO2/kg-hydrogen. High-purity syngas with 89.47 vol% of (H2 + CO) was obtained, and the gas energy conversion efficiency (GECE) of the process reached 75.65%. The study shows that in the cascaded catalytic reforming process, cracking of the large oxygenates and reforming of the small molecules are promoted sequentially in separated biochar + NiAlO catalyst layers, which maximizes the syngas production and improves the activity and stability of the Ni-based catalyst. © 2022 The Author(s)
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