| 1. |
- Aguilar-Sanchez, Andrea, et al.
(author)
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Charged ultrafiltration membranes based on TEMPO-oxidized cellulose nanofibrils/poly(vinyl alcohol) antifouling coating
- 2021
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 11:12, s. 6859-6868
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Journal article (peer-reviewed)abstract
- This study reports the potential of TEMPO-oxidized cellulose nanofibrils (T-CNF)/poly(vinyl alcohol) (PVA) coatings to develop functionalized membranes in the ultrafiltration regime with outstanding antifouling performance and dimensional/pH stability. PVA acts as an anchoring phase interacting with the polyethersulfone (PES) substrate and stabilizing for the hygroscopic T-CNF via crosslinking. The T-CNF/PVA coated PES membranes showed a nano-textured surface, a change in the surface charge, and improved mechanical properties compared to the original PES substrate. A low reduction (4%) in permeance was observed for the coated membranes, attributable to the nanometric coating thickness, surface charge, and hydrophilic nature of the coated layer. The coated membranes exhibited charge specific adsorption driven by electrostatic interaction combined with rejection due to size exclusion (MWCO 530 kDa that correspond to a size of similar to 35-40 nm). Furthermore, a significant reduction in organic fouling and biofouling was found for T-CNF/PVA coated membranes when exposed to BSA and E. coli. The results demonstrate the potential of simple modifications using nanocellulose to manipulate the pore structure and surface chemistry of commercially available membranes without compromising on permeability and mechanical stability.
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| 2. |
- Aguilar-Sánchez, Andrea, 1987-, et al.
(author)
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Nano-cellulose coatings for antifouling and mechanically enhanced polyethersulfone (PES) membranes
- 2019
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In: Nordic Polymer Days 2019. ; , s. 92-92
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Conference paper (peer-reviewed)abstract
- Membrane technology is commonly used for filtration processes of industrial wastewater. Using membranes for water filtration is a safe and energy efficient solution. One of the main problems that arises during the usage of membranes is the fouling effects. Fouling increases the membrane separation resistance, reduces productivity due to a flux decline and affect membrane selectivity. These effects can be avoid by modifying the surface of the membranes using bio-based materials such as nano-cellulose. Nano-cellulose is a great example of a material obtained from renewable resources, which provides high reinforcement and antifouling properties to membranes.The aim of this work was the development of coatings with cellulose nano-crystals (CNC) and Tempooxidized cellulose nano-fribrils (T-CNF) using polyvinyl-alcohol (PVOH), as binding phase to enhance mechanical and antifouling properties over pure commercial PES membranes. The coatings were chemically crosslinked to increase mechanical properties and to improve stability of the coating and avoid swelling. It is expected that by avoiding swelling, permeability remains stable through time. All coating formulations remained stable after 10 hours of crossflow filtration. Mechanical properties of the coated membranes were improved in both dry and wet conditions, showing higher values of tensile strenght and E modulus compared to the uncoated ones. In addition, coated membranes showed high hydrophilicity and low adherence of bovine serum albumin (BSA).The coatings developed showed stability over PES membranes and provide them with a nanostructured surface which showed an extended durability in use. The modified surface membranes presented good mechanical properties in dry and wet conditions, high flux, high hydrophilicity, resistance to BSA fouling and to different pH environments. Moreover, these modified membranes showed promising results for fast upscaling at industrial level due to the simplicity of the coating process and the availability of the materials in the market.
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| 3. |
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| 4. |
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| 5. |
- Aguilar-Sanchez, Andrea, et al.
(author)
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Waterborne nanocellulose coatings for improving the antifouling and antibacterial properties of polyethersulfone membranes
- 2021
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In: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 620
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Journal article (peer-reviewed)abstract
- This article presents a waterborne nanocellulose coating process to change the surface characteristics and mitigate fouling of commercially available polyethersulfone (PES) microfiltration membranes. An extensive comparative study between nanoporous and nano-textured layers composed of cellulose nanocrystals (CNC) or TEMPO-oxidized cellulose nanofibrils (T-CNF), which were coated on the PES membrane by taking advantage of the electrostatic interactions between the PES substrate, a polyallylamine hydrochloride (PAHC1) anchoring layer, and the nanocellulose functional layer. Coated PES membranes exhibited decreased surface roughness and pore sizes as well as rejection of compounds with a M-w above 150 kDa, while the water permeability and mechanical properties of remained largely unaffected. The coatings improved the wettability as confirmed by a reduction of the contact angle by up to 52% and exhibited a higher negative surface charge compared to the uncoated membranes over a pH range of 4-8. A significant reduction in organic fouling was observed for the coated membranes demonstrated by bovine serum albumin (BSA) adsorption studies on T-CNF and CNC surfaces using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), UV-vis spectroscopy and FTIR mapping after exposing the membranes to dynamic adsorption of BSA. The T-CNF coating exhibited effective antibacterial action against Escherichia coli (E. coli) attributed to the pH reduction effect induced by the carboxyl groups; while CNC coatings did not show this property. This work demonstrates a simple, green, and easy-to-scale layer-by-layer coating process to tune the membrane rejection and to improve antifouling and antibacterial properties of commercially available membranes.
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| 6. |
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| 7. |
- 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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| 8. |
- Goetz, Lee, et al.
(author)
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Superhydrophilic anti-fouling electrospun cellulose acetate membranes coated with chitin nanocrystals for water filtration
- 2016
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In: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 510, s. 238-248
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Journal article (peer-reviewed)abstract
- Electrospun cellulose acetate (CA) random mats were prepared and surface coated with chitin nano crystals (ChNC) to obtain water filtration membranes with tailored surface characteristics. Chitin nano crystals self-assembled on the surface of CA fibers into homogenous nanostructured networks during drying that stabilized via hydrogen bonding and formed webbed film-structures at the junctions of the electrospun fibers. Coating of CA random mats using 5% chitin nanocrystals increased the strength by 131% and stiffness by 340% accompanied by a decrease in strain. The flux through these membranes was as high as 14217 L m(-2) h(-1) at 0.5 bar. The chitin nanocrystal surface coating significantly impacted the surface properties of the membranes, producing a superhydrophilic membrane (contact angle 0) from the original hydrophobic CA mats (contact angle 132 degrees). The coated membranes also showed significant reduction in biofouling and biofilm formation as well as demonstrated improved resistance to fouling with bovine serum albumin and humic acid fouling solutions. The current approach opens up an easy, environmental friendly and efficient route to produce highly hydrophilic membranes with high water flux and low fouling for microfiltration water purification process wash water from food industry for biological contaminants.
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| 9. |
- Jalvo, Blanca, et al.
(author)
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Coaxial poly(lactic acid) electrospun composite membranes incorporating cellulose and chitin nanocrystals
- 2017
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In: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 544, s. 261-271
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Journal article (peer-reviewed)abstract
- In this study, we used electrospinning to produce core-shell nanofibers of poly(lactic acid) as core and polyacrylonitrile/ cellulose nanocrystals (CNC) or polyacrylonitrile/chitin nanocrystals (ChNC) as shell. Electrospun materials prepared at different nanocrystal concentrations were tested and assayed as microfiltration membranes. The coaxial membranes presented a maximum pore size in the 1.2-2.6 mu m range and rejections > 85% for bacterial cells (0.5 x 2.0 mu m) and > 99% for fungal spores (> 2 mu m). The morphological and mechanical properties and the water permeability of the nanocomposite membranes were studied. The morphological characterization showed random fibers of beadless and well-defined core/shell structured fibers with diameter generally below the micron size with presence of secondary ultrafine nanofibers. Tensile strength and Young's modulus of elasticity improved with respect to coaxial membranes without nanocrystals with best mechanical properties achieved at 5 wt% CNC and 15 wt% ChNC loadings. The enhancement was attributed to the reinforcing effect of the percolating network of cellulose nanocrystals. Water permeability increased for all membranes loaded with nanocrystals with respect to the coaxial fibers without nanocrystals, the highest corresponding to ChNC composites with up to a 240% increase over non-loaded membranes. Composite membranes prepared with CNC in their shell were hydrophilic, in contrast with the hydrophobic PLA core, while coaxial fibers with ChNC were superhydrophilic. CNC membranes were negatively charged but ChNC originated neutral or positively charged membranes due to the contribution of deacetylated chitin structural units. Upon exposure to E. coli cultures, composite membranes containing ChNC showed a high antimicrobial action and were essentially free of bacterial colonization under strong biofilm formation conditions.
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| 10. |
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| 11. |
- Jalvo, Blanca, et al.
(author)
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Water Filtration Membranes Based on Non-Woven Cellulose Fabrics : Effect of Nanopolysaccharide Coatings on Selective Particle Rejection, Antifouling, and Antibacterial Properties
- 2021
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In: Nanomaterials. - : MDPI AG. - 2079-4991. ; 11:7
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Journal article (peer-reviewed)abstract
- This article presents a comparative study of the surface characteristics and water purification performance of commercially available cellulose nonwoven fabrics modified, via cast coating, with different nano-dimensioned bio-based carbohydrate polymers, viz. cellulose nanocrystals (CNC), TEMPO-oxidized cellulose nanofibers (T-CNF), and chitin nanocrystals (ChNC). The surface-modified nonwoven fabrics showed an improvement in wettability, surface charge modification, and a slight decrease of maximum pore size. The modification improved the water permeance in most of the cases, enhanced the particle separation performance in a wide range of sizes, upgraded the mechanical properties in dry conditions, and showed abiotic antifouling capability against proteins. In addition, T-CNF and ChNC coatings proved to be harmful to the bacteria colonizing on the membranes. This simple surface impregnation approach based on green nanotechnology resulted in highly efficient and fully bio-based high-flux water filtration membranes based on commercially available nonwoven fabrics, with distinct performance for particle rejection, antifouling and antibacterial properties.
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| 12. |
- Karnaouri, Anthi C., et al.
(author)
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Lytic Polysaccharide Monooxygenase-Assisted Preparation of Oxidized-Cellulose Nanocrystals with a High Carboxyl Content from the Tunic of Marine Invertebrate Ciona intestinalis
- 2020
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In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 8:50, s. 18400-18412
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Journal article (peer-reviewed)abstract
- The tunicate species Ciona intestinalis is a fast-growing marine invertebrate animal that contains cellulose in its outer part - the tunic. The high crystallinity and microfibril aspect ratio of tunicate cellulose make it an excellent starting material for the isolation of nanocellulose. In the present work, tunic from C. intestinalis was subjected to organosolv pretreatment followed by bleaching and acid-hydrolysis steps for the isolation of nanocrystals. Applying an intermediate enzymatic treatment step with a lytic polysaccharide monooxygenase (LPMO) from the thermophilic fungus Thermothelomyces thermophila was proved to facilitate the isolation of nanocellulose and to improve the overall process yield, even when the bleaching step was omitted. LPMOs are able to oxidatively cleave the glycosidic bonds of a polysaccharide substrate, either at the C1 and/or C4 position, with the former leading to introduction of carboxylate moieties. X-ray photoelectron spectroscopy analysis showed a significant increase in the atomic percentage of the Câ•O/O-C-O and O-Câ•O bonds upon the addition of LPMO, while the obtained nanocrystals exhibited higher thermal stability compared to the untreated ones. Moreover, an enzymatic post-treatment with LPMOs was performed to additionally functionalize the cellulose nanocrystals. Our results demonstrate that LPMOs are promising candidates for the enzymatic modification of cellulose fibers, including the preparation of oxidized-nanocellulose, and offer great perspectives for the production of novel biobased nanomaterials. ©
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| 13. |
- Valencia, Luis, et al.
(author)
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Fully bio-based zwitterionic membranes with superior antifouling and antibacterial properties prepared via surface-initiated free-radical polymerization of poly(cysteine methacrylate)
- 2018
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 6:34
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Journal article (peer-reviewed)abstract
- This article proposes a strategy to prepare membranes that combine the network characteristics of micro/nanocellulose with grafted zwitterionic poly(cysteine methacrylate) (PCysMA) to develop fully bio-based membranes with antifouling properties. The surface characteristics of the membranes were studied, together with static adsorption of bovine serum albumin (BSA) and S. aureus for evaluating the antifouling properties of the membranes. Experimental data revealed a homogeneous modification that resulted in excellent antifouling properties with a reduction of 85% in biofilm formation and enhanced antimicrobial activity. Moreover, we introduced a novel method to determine the pore size of membranes in the wet-state and assess the antifouling performance in situ by synchrotron-based SAXS. This allowed us to observe in real-time the decrease in pore size upon adsorption of BSA during filtration, and how this phenomenon is strongly suppressed by grafting of PCysMA. The importance of this work lies in introducing a simple method to yield cellulosic membranes with superior antifouling properties, which could significantly increase their potential for water treatment applications.
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| 14. |
- Valencia, Luis, et al.
(author)
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Nanolignocellulose extracted from environmentally undesired prosopis juliflora
- 2019
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:2, s. 4330-4338
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Journal article (peer-reviewed)abstract
- Rising sustainability demands the search of new low-market-value sources of lignocellulosic biomass as raw material for nanocellulose processing. In this paper, we accordingly propose the isolation of nanocellulose from Prosopis juliflora, an abundant but environmentally undesired tree. P. juliflora wood was powered, refined by steam explosion and bleaching, and subsequently used to isolate cellulose nanocrystals and nanofibers by means of acid hydrolysis and mechanical fibrillation. The derived nanocrystals had a rod-shaped structure with an average diameter of 20 nm and length of 150 nm, whereas the nanofibers had a diameter of 10 nm and length in micron size. Moreover, we report a simple method to isolate nanolignocellulose by using partially bleached P. juliflora as feedstock. The presence of lignin provided antioxidant and antimicrobial activity to nanocellulose, as well as hydrophobicity and increased thermal stability. The study demonstrates the successful use of P. juliflora to extract functional nanomaterials, which compensate for its environmental concern and declining market interest.
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