| 1. |
- Abdelhamid, Hani Nasser, et al.
(author)
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CelloZIFPaper : Cellulose-ZIF hybrid paper for heavy metal removal and electrochemical sensing
- 2022
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In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 446
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Journal article (peer-reviewed)abstract
- The processing of hierarchical porous zeolitic imidazolate frameworks (ZIF-8) into a cellulose paper using sheet former Rapid-Kothen (R.K.) is reported. The procedure is a promising route to overcome a significant bottleneck towards applying metal-organic frameworks (MOFs) in commercial products. ZIF-8 crystals were integrated into cellulose pulp (CP) or TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-oxidized cellulose nanofibrils (TOCNF) following an in-situ or ex-situ process; the materials were denoted as CelloZIFPaper_In Situ and CelloZIFPaper_Ex Situ, respectively. The materials were applied as adsorbents to remove heavy metals from water, with adsorption capacities of 66.2-354.0 mg/g. CelloZIFPaper can also be used as a stand-alone working electrode for the selective sensing of toxic heavy metals, for instance, lead ions (Pb2+), using electrochemical-based methods with a limit of detection (LOD) of 8 mu M. The electrochemical measurements may advance 'Lab-onCelloZIFPaper' technologies for label-free detection of heavy metal ions.
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| 2. |
- Georgouvelas, Dimitrios, et al.
(author)
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All-cellulose functional membranes for water treatment : Adsorption of metal ions and catalytic decolorization of dyes
- 2021
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 264
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Journal article (peer-reviewed)abstract
- In this study, we present a facile, one-step method for the manufacturing of all-cellulose, layered membranes containing cellulose nanocrystals (CNC), TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibers (TO-CNF), or zwitterionic polymer grafted cellulose nanocrystals (CNC-gPCysMA) as functional entities in combination with cellulose fibers and commercial grade microfibrillated cellulose. The presence of active sites such as hydroxyl, carbonyl, thioethers, and amines, gave the membranes high adsorption capacities for the metal ions Au (III), Co (II), and Fe (III), as well as the cationic organic dye methylene blue (MB). Furthermore, the membranes served as excellent metal-free catalysts for the decolorization of dyes via hydrogenation. A 3-fold increase of the hydrogenation efficiency for cationic dyes such as rhodamine B (RhB) and methylene blue was obtained in the presence of membranes compared to NaBH4 alone. Water-based processing, the abundance of the component materials, and the multifunctional characteristics of the membranes ensure their potential as excellent candidates for water purification systems.
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| 3. |
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| 4. |
- Georgouvelas, Dimitrios, et al.
(author)
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In situ modified nanocellulose/alginate hydrogel composite beads for purifying mining effluents
- 2023
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In: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 5:21, s. 5892-5899
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Journal article (peer-reviewed)abstract
- Biobased adsorbents and membranes offer advantages related to resource efficiency, safety, and fast kinetics but have challenges related to their reusability and water flux. Nanocellulose/alginate composite hydrogel beads were successfully prepared with a diameter of about 3-4 mm and porosity as high as 99%. The beads were further modified with in situ TEMPO-mediated oxidation to functionalize the hydroxyl groups of cellulose and facilitate the removal of cationic pollutants from aqueous samples at low pressure, driven by electrostatic interactions. The increased number of carboxyl groups in the bead matrix improved the removal efficiency of the adsorbent without compromising the water throughput rate; being as high as 17 000 L h(-1) m(-2) bar(-1). The absorptivity of the beads was evaluated with UV-vis for the removal of the dye Methylene Blue (91% removal) from spiked water and energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) elemental analyses for the removal of Cd2+ from industrial mining effluents. The modified beads showed a 3-fold increase in ion adsorption and pose as excellent candidates for the manufacturing of three-dimensional (3-D) column filters for large-volume, high flux water treatment under atmospheric pressure.
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| 5. |
- Georgouvelas, Dimitrios, 1985-, et al.
(author)
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In situ modified nanocellulose/alginate hydrogel composite beads for purifying mining effluents
- 2023
-
In: Nanoscale Advances. - 2516-0230. ; 5:21, s. 5892-5899
-
Journal article (peer-reviewed)abstract
- Biobased adsorbents and membranes offer advantages related to resource efficiency, safety, and fast kinetics but have challenges related to their reusability and water flux. Nanocellulose/alginate composite hydrogel beads were successfully prepared with a diameter of about 3–4 mm and porosity as high as 99%. The beads were further modified with in situ TEMPO-mediated oxidation to functionalize the hydroxyl groups of cellulose and facilitate the removal of cationic pollutants from aqueous samples at low pressure, driven by electrostatic interactions. The increased number of carboxyl groups in the bead matrix improved the removal efficiency of the adsorbent without compromising the water throughput rate; being as high as 17 000 L h−1 m−2 bar−1. The absorptivity of the beads was evaluated with UV-vis for the removal of the dye Methylene Blue (91% removal) from spiked water and energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) elemental analyses for the removal of Cd2+ from industrial mining effluents. The modified beads showed a 3-fold increase in ion adsorption and pose as excellent candidates for the manufacturing of three-dimensional (3-D) column filters for large-volume, high flux water treatment under atmospheric pressure.
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| 6. |
- Georgouvelas, Dimitrios, 1985-
(author)
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Modified and hybrid cellulose-based materials for water purification
- 2022
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Doctoral thesis (other academic/artistic)abstract
- The need for clean water has led to the development of several different water treatment methods as well as to a large number of organic, inorganic, hybrid and/or composite materials that are used in these methods. Cellulose, being a highly abundant biopolymer with meritorious properties, such as high mechanical strength, tunable surface chemistry, high aspect ratio and surface area, to mention a few, is exploited in the current thesis for water treatment applications. Cellulose and its nanoscaled derivatives (i.e. cellulose nanocrystals and cellulose nanofibers) are modified or hybridized to achieve multiple functionalities.Cellulose and lignocellulose nanocrystals were successfully prepared by mechanical treatment from the residue of bioethanol production and were decorated with zwitterionic polymer grafts through controlled radical polymerization reactions. The presence of residual lignin and polymer grafts was investigated which showed that especially the polymer grafting can significantly improve the antibacterial and antifouling performance of nanocellulose.Functional cellulose-based membranes were prepared in a one-step water-based process. The membranes were evaluated as adsorbents for the removal of dyes and metal ions as well as metal-free catalysts for the decolorization of dyes Methylene Blue (MB) and Rhodamine B (RhB). The membranes exhibited maximum adsorption capacity of 78.6 mg/g for Co2+, up to 100 % of MB removal efficiency and up to 3-fold increase in the decolorization of MB.Both in-situ and ex-situ growth of ZIF-8 crystals was performed on the surface of cellulose and nanocellulose and cellulose/ZIF hybrid membranes were manufactured. The adsorption capacity of the membranes was tested with Cd2+, Cu2+, Fe3+, and Pb2+, exhibiting a maximum adsorption capacity of 354 mg/g for Cu2+. Furthermore, the membranes showed potential for use as self-standing electrode for the detection of Pb2+.Processing of cellulose/alginate composite hydrogels in the form of highly porous beads was successful. The surface of the beads was modified via in-situ TEMPO oxidation for the introduction of carboxyl groups. Adsorption of cationic contaminants as dyes and metal ions (MB and Cd2+ were used as models, respectively) was enhanced with in-situ modification. Removal of metal ions from the mining industry wastewater using modified cellulose/alginate hydrogel beads confirmed the potential of the adsorbent in complex water sources.All-cellulose flat sheets (100 × 20 cm) were produced via a water-based process using a Formette dynamic sheet former. The sheets exhibited excellent mechanical properties attributed to the alignment of the micro and nanofibers that this process offers. The adsorption performance of the sheets was evaluated both with Irgalite Blue RL and Irgalite Violet H dyes, which are highly used in paper and pulp industries as dyes models, and Fe3+, Mg2+, Cd2+, Co2+, Cr3+, and Mn2+ as metal ion models. A maximum removal efficiency of 83% for IB RL and maximum adsorption capacity of 737 mg/g for Mg2+.The work shows the potential of cellulose as a sustainable and scalable platform for the tailoring of multifunctional materials for water treatment with cationic pollutants removal, antifouling, antibacterial and sensing capabilities.
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| 7. |
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| 8. |
- Georgouvelas, Dimitrios, et al.
(author)
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Residual Lignin and Zwitterionic Polymer Grafts on Cellulose Nanocrystals for Antifouling and Antibacterial Applications
- 2020
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In: ACS APPLIED POLYMER MATERIALS. - : American Chemical Society (ACS). - 2637-6105. ; 2:8, s. 3060-3071
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Journal article (peer-reviewed)abstract
- Hybrid materials from nanocellulose, lignin, and surface- grafted zwitterionic poly(sulfobetaine methacrylate) (PSBMA) chains are prepared to attain antifouling bio-based nanomaterials with enhanced antibacterial performance. The grafting of PSBMA from both cellulose and lignocellulose nanocrystals (CNC and LCNC, respectively) is attempted; however, the materials' analysis with FTIR, XPS, and solid-state C-13 NMR reveals that the grafting on LCNC is negligible. Antifouling and antibacterial performances of CNC and LCNC, as well as PSBMA-grafted CNC, are evaluated by using quartz crystal microbalance with dissipation monitoring, confocal microscopy, and the agar diffusion method using bovine serum albumin and E. coli ACTT 8937 as protein model and bacterial model, respectively. The results demonstrate that the grafting of CNC with PSBMA improves the antifouling and antibacterial activity of the material compared to pristine CNC and LCNC.
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| 9. |
- González-Zapata, José Luis, et al.
(author)
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Introducing random bio-terpene segments to high cis-polybutadiene : making elastomeric materials more sustainable
- 2020
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10:72, s. 44096-44102
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Journal article (peer-reviewed)abstract
- In this work, we explore the statistical copolymerization of 1,3-butadiene with the terpenic monomers myrcene and farnesene, carried out via coordination polymerization using a neodymium-based ternary catalytic system. The resultant copolymers, poly(butadiene-co-myrcene) and poly(butadiene-co-farnesene), were synthesized at different monomer ratios, elucidating the influence of the bio-based monomer content over the kinetic variables, molecular and thermal properties, and the reactivity constants (Fineman-Ross and Kelen-Tudos methods) of the resultant copolymers. The results indicate that through the herein employed conditions, it is possible to obtain more sustainable high-cis (approximate to 95%) polybutadiene elastomers with random and tunable content of bio-based monomer. Moreover, the polymers exhibit fairly high molecular weights and a rather low dispersity index. Upon copolymerization, the T-g of high-cis PB can be shifted from -106 to -75 degrees C (farnesene) or -107 to -64 degrees C (myrcene), without altering the microstructure control. This work contributes to the development of more environmentally friendly elastomers, to form green rubber materials.
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| 10. |
- Karim, Zoheb, et al.
(author)
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Upscaled engineered functional microfibrillated cellulose flat sheet membranes for removing charged water pollutants
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Other publication (other academic/artistic)abstract
- Polymeric composite membranes have shown great potential in removing pollutantsfrom water. A significant limitation of polymeric membranes is the centimeter-sizeddimensions, which limit their application at the pilot or industrial scales. In the currentstudy, flat sheet functional membranes of microfibrillated cellulose (MFC) withmixed and layered architectures are produced using the up-scaled Dynamic SheetFormer (Formette) in a fully water-based-system, and their potential for the removalof charged impurities from the aqueous medium is evaluated. The processing ofcomposite membranes is unique in terms of their size (1m × 20 cm), assembled MFCarchitectures, controlled/tunable porosity, functional groups densities, and freestanding at high water pressure. Such properties could be difficult to achieve with alab-scale processing setup. It is shown that the MFC assembly has a direct influenceon the pollutant removal efficiency, and again the layered architecture turns out to bea more efficient scavenger of the charged pollutants due to the combined actions ofelectrostatic interactions, hydrogen bonding, and size exclusion, which areresponsible for an ultrafast separation of the impurities through the flat sheets. Theseexperimental results are supported by reactive molecular dynamics simulations ofrepresentative model systems that provided possible realistic scenarios at theatomic/molecular scaleAll the data confirm the scalability and tunability of theproduced MFC-based water cleaning membranes, which show high adsorptioncapacity, flexibility, hydrolytic stability, and mechanical robustness.
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