Carbon dioxide plasma treated PVDF electrospun membrane for the removal of crystal violet dyes and iron oxide nanoparticles from water

International audienceHere we reported a reactive plasma treatment of polyvinylidene fluoride (PVDF) electrospun membrane by using carbon dioxide (CO2) plasma in order to reduce the hydrophobicity of the PVDF membrane and thereby used to remove toxic crystal violet dye (CV) and iron oxide (Fe2O3) nanoparticles from water. The demonstrated plasma treated PVDF electrospun membrane showed a decrement in the hydrophobicity after plasma treatment. Most of the microfiltration membranes based on PVDF were fabricated via phase inversion technique and solvent casting. The main drawback of these methods is that to obtain membranes with uniform pore size. Moreover, the membranes fabricated via phase inversion and solvent casting process have low surface area whereas in the membranes via electrospinning technique have interconnected pore structure with high surface area and uniform pore size. The contact angle of the neat PVDF electrospun membrane and plasma treated PVDF electrospun membrane were 141°and 102°respectively. FTIR studies revealed that, after CO2 plasma treatment, highly negative carboxylate (COO-) groups were formed on the surface of the PVDF electrospun membrane. With the 10 mg/L of crystal violet (CV) aqueous solution, the dye adsorption capacity was 1.368 mg/g of the membrane for neat PVDF membrane and 3.84 mg/g of the membrane for plasma treated PVDF membrane. It was found that, the CO2 plasma treated PVDF membrane had two- or three-times greater adsorption capacity then neat PVDF membrane against crystal violet dyes which was due to the strong electrostatic interaction between the highly negative carboxyl groups on the surface of plasma treated PVDF electrospun membrane and protonated CV dye. Both neat PVDF membrane and plasma treated PVDF membrane showed excellent filtration capacity against Fe2O3 nanoparticles. The demonstrated plasma treated PVDF membrane could successfully remove iron oxide nanoparticles and crystal violet dyes from water via size exclusion and adsorption mechanism respectively

Robust superhydrophobic cellulose nanofiber aerogel for multifunctional environmental applications

The fabrication of superadsorbent for dye adsorption is a hot research area at present. However, the development of low-cost and highly efficient superadsorbents against toxic textile dyes is still a big challenge. Here, we fabricated hydrophobic cellulose nanofiber aerogels from cellulose nanofibers through an eco-friendly silanization reaction in liquid phase, which is an extremely efficient, rapid, cheap, and environmentally friendly procedure. Moreover, the demonstrated eco-friendly silanization technique is easy to commercialize at the industrial level. Most of the works that have reported on the hydrophobic cellulose nanofiber aerogels explored their use for the elimination of oil from water. The key novelty of the present work is that the demonstrated hydrophobic cellulose nanofibers aerogels could serve as superadsorbents against toxic textile dyes such as crystal violet dye from water and insulating materials for building applications. Here, we make use of the possible hydrophobic interactions between silane-modified cellulose nanofiber aerogel and crystal violet dye for the removal of the crystal violet dye from water. With a 10 mg/L of crystal violet (CV) aqueous solution, the silane-modified cellulose nanofiber aerogel showed a high adsorption capacity value of 150 mg/g of the aerogel. The reason for this adsorption value was due to the short-range hydrophobic interaction between the silane-modified cellulose nanofiber aerogel and the hydrophobic domains in crystal violet dye molecules. Additionally, the fabricated silane-modified cellulose nanofiber hydrophobic aerogels exhibited a lower thermal conductivity value of 0.037 W\ub7m -1 K -1 , which was comparable to and lower than the commercial insulators such as mineral wools (0.040 W\ub7m -1 K -1 ) and polystyrene foams (0.035 W\ub7m -1 K -1 ). We firmly believe that the demonstrated silane-modified cellulose nanofiber aerogel could yield an eco-friendly adsorbent that is agreeable to adsorbing toxic crystal violet dyes from water as well as active building thermal insulators

Utilization of agrowaste-derived nanoparticles as reinforcement in microfilled epoxy composites

The substantial release of oil palm ash into ground water has been a serious concern to the environmentalist due to the enormous generation of oil palm ash waste from oil palm incineration. The effective utilization of this agrowaste is yet to be fully exploited. In this context, herein we, investigated the potential of oil palm ash nanofiller as an effective reinforcement in epoxy-based composites. Transmission electron microscopy (TEM) revealed that the prepared oil palm ash nanoparticles had circular morphology with particle size in the range of 20to 25 nm. X-ray diffraction patterns of the prepared oil palm ash nanoparticles revealed the crystalline nature of the oil palm ash nanoparticles. Tensile strength and tensile modulus of the epoxy composites were substantially improved to 64, 67, 70,and 75 MPa and 1.01,1.05,1.16,and 1.18 MP a at oil palm ash nanofiller loading of 1%,2%,3%,and %,respectively.The impact strength of nanocomposite was enhanced from 2.7015 ± 0.13 kJ/m2to 3.98 ± 0.17kJ/m2 at 3% of oil palm ash nanofiller loading. The optimum values of mechanical properties were attained at 4% filler loading,after which further loading resulted in the decrement of mechanical properties of epoxy nanocomposite. Thermal stability of the epoxy nanocomposite was enhanced substantially to 435 °C by the incorporation of oil palm ash nanofillers. This study proved that nano-sized oil palm ash could be an efficient reinforcement in polymer composite

Matériaux fonctionnels à base de nanocellulose pour la purification de l'eau et l’atténuation des micro-ondes

After agriculture, the textile dyeing and finishing industry has generated a large water pollution problem as most of the chemicals coming from these industries are highly toxic and directly or indirectly affect human health. Another important issue is the Electro Magnetic (EM) pollution which deteriorates the performance and life of electronic gadgets and also adversely affects the human health. In this context, cellulose nanomaterial’s inherent fibrous nature and remarkable mechanical properties combined with low cost, biocompatibility and sustainable source, suggest huge potential as a component in water filtration membranes and green microwave attenuators in future. The main objective of this thesis is to fabricate cellulose nanofibers based functional constructs for clean water and microwave suppression. The presented unique method to produce novel absorbent material from cellulose nanofibers via non-solvent assisted method using Meldrum’s acid as an esterification agent for absorption of toxic dyes from water has not been addressed till date. This finding offers a new platform for the surface treatment of cellulose nanofibers using solvent free green technology. Conventionally, metals were used to shield EM waves but are highly undesirable due to their inherent drawbacks such as higher weights, corrosive nature and difficulty of processing into intricate shapes. Conductive cellulose nanopapers can offer a potential green feasible solution to this problem. The presented conductive cellulose nanopapers with an effective total shielding effectiveness of > 20 B will be a promising candidate for commercial device applications and will be an effective platform for developing eco-friendly green based attenuators.Après l'agriculture, l'industrie textile a engendré un important problème de pollution de l'eau car la plupart des produits chimiques provenant de ces industries sont hautement toxiques et affectent directement ou indirectement la santé humaine. La pollution électromagnétique (EM) est un autre problème important qui détériore les performances et la durée de vie des objets électroniques et nuit également à la santé humaine. Dans ce contexte, la nature fibreuse inhérente des nanomatériaux cellulosiques et leurs propriétés mécaniques remarquables, associées à une biocompatibilité et à une ressource durable, offrent un potentiel énorme en tant que composant dans les membranes de filtration de l'eau et les atténuateurs de micro-ondes verts. L'objectif principal de cette thèse est de fabriquer des objets fonctionnels à base de nanofibres de cellulose pour la filtration de l'eau et la suppression des micro-ondes. La méthode présentée dans ce manuscrit décrit un nouveau matériau absorbant à partir de nanofibres de cellulose par l'intermédiaire d'une méthode non solvatée utilisant l'acide de Meldrum comme agent d'estérification pour l'absorption de colorants toxiques. Cette innovation offre une nouvelle plate-forme pour le traitement de surface des nanofibres de cellulose utilisant une technologie verte sans solvant. Classiquement, les métaux ont été utilisés pour protéger les ondes électromagnétiques, mais sont fortement indésirables en raison de leurs inconvénients tels que des poids plus élevés, une nature corrosive et une difficulté de traitement en formes complexes. Les nano- papiers, à base de cellulose conductrice, peuvent offrir une solution verte à ce problème. La cellulose rendue conductrice présente une efficacité de blindage totale de plus de 20 B. Il s’agit d’une plate-forme efficace pour développer des atténuateurs verts respectueux de l'environnement

Interfacial Compatibility Evaluation on the Fiber Treatment in the Typha Fiber Reinforced Epoxy Composites and Their Effect on the Chemical and Mechanical Properties

Natural fiber composites have been widely used for various applications such as automotive components, aircraft components and sports equipment. Among the natural fibers Typha spp have gained considerable attention to replace synthetic fibers due to their unique nature. The untreated and alkali-treated fibers treated in different durations were dried under the sun for 4 h prior to the fabrication of Typha fiber reinforced epoxy composites. The chemical structure and crystallinity index of composites were examined via FT-IR and XRD respectively. The tensile, flexural and impact tests were conducted to investigate the effect of the alkali treated Typha fibers on the epoxy composite. From the microscopy analysis, it was observed that the fracture mechanism of the composite was due to the fiber and matrix debonding, fiber pull out from the matrix, and fiber damage. The tensile, flexural and impact strength of the Typha fiber reinforced epoxy composite were increased after 5% alkaline immersion compared to untreated Typha fiber composite. From these results, it can be concluded that the alkali treatment on Typha fiber could improve the interfacial compatibility between epoxy resin and Typha fiber, which resulted in the better mechanical properties and made the composite more hydrophobic. So far there is no comprehensive report about Typha fiber reinforcing epoxy composite, investigating the effect of the alkali treatment duration on the interfacial compatibility, and their effect on chemical and mechanical of Typha fiber reinforced composite, which plays a vital role to provide the overall mechanical performance to the composite

Nanocellulose-Based Membranes for Water Purification

Scarcity and contamination of worldwide drinking water demand advanced, effective water purification methodologies. Eliminating numerous contaminants, such as heavy metals, toxic textile dyes, pesticides, oil, and other industrial, as well as agricultural, wastes, from water has become a serious concern because of their adverse effects on human health and the ecosystem. Recently, developments in nanoscience and nanotechnology propose that several of the present problems relating to water quality could be greatly reduced by using nanomaterials because of their good adsorption efficiency, higher surface area, and greater active sites for interaction with contaminants in water. In this context, nanocellulose is the most abundant and renewable polymer available globally and consists of repeating β-d-glucopyranose units covalently linked through acetal functions between the hydroxyl groups of C4 and C1 carbon atoms that provide it chirality and reactivity properties. Nanocellulose is a fascinating material for practical applications because it is cost-effective, is renewable, and can be handled at huge scale using conventional wood industry techniques. Nanocellulose is a valuable filtration material because it is affordable, sustainable, inert, and stable at a broad range of pH/ionic strength. Moreover, the abundant availability of the surface hydroxyl groups on the nanocellulose facilitates various surface chemistries that can be explored for targeting various contaminants in water. This chapter covers the recent developments and literature of nanocellulose in the field of water purification

Advances in cellulose nanomaterials

International audienceResearch on nanocellulose has significantly increased over the past few decades, owing to the various attractive characteristics of this material, such as renewability, widespread availability, low density, excellent mechanical properties, economic value, biocompatibility, and biodegradability. Nanocellulose categorized into two main types, namely cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). In this review, we present the recent advances made in the production of CNFs and CNCs. In addition to the conventional mechanical and chemical treatments used to prepare CNFs and CNCs, respectively, other promising techniques as well as pretreatment processes have been also proposed in recent times, in an effort to design an economically efficient and eco-friendly production route for nanocellulose. Further, while the hydrophilic nature of nanocellulose limits its use in polymeric matrices and in some industrial applications, the large number of hydroxyl groups on the surface of nanocellulose provides a suitable platform for various kinds of modification treatments. The various chemical and physical surface treatment procedures reported for nanocellulose have been reviewed in this paper. Finally, in this review, we summarize the life cycle assessment studies conducted so far on nanocellulose, which quantify the environmental impact of nanocellulose products. The current paper is a comprehensive review of the recent literature on nanostructured cellulose

Ultra-fast heat dissipating aerogels derived from polyaniline anchored cellulose nanofibers as sustainable microwave absorbers

International audienceElectromagnetic (EM) pollution is ubiquitous and has soared to a great extent in the past few decades. The use of plant sourced cellulose nanofibers to fabricate sustainable and high performance electromagnetic shielding materials is foreseen as a green solution by the electronics industry to address this unseen pollutant. In this view, we report a facile and environmentally benign strategy to synthesize ultra-light and highly conductive aerogels derived from cellulose nanofibers (CNF) decorated with polyaniline (PANI) via a simple in-situ polymerization and subsequent freeze drying process devoid of any volatile organic solvents. The obtained conductive aerogels exhibited density as low as 0.01925 g/cc with a maximum EMI shielding value −32 dB in X band region. These porous shields demonstrated strong microwave absorption behavior (95 %) with minimal reflection (5 %) coupled with high specific EMI SE value ∼1667 dB.cm3. g−1 which make these aerogels a potential candidate for use in telecommunication, military and defense applications

Meldrum's Acid Modified Cellulose Nanofiber-Based Polyvinylidene Fluoride Microfiltration Membrane for Dye Water Treatment and Nanoparticle Removal

International audienceThe work presented here aims to study and compare the performance of a polyvinylidene fluoride (PVDF) electrospun membrane, unmodified cellulose nanofiber (CNF) based PVDF membrane, and Meldrum's acid (2,2-dimethyl1,3-dioxane-4,6-dione) modified CNF-based PVDF membranes against the Fe2O3 nanoparticle filtration and crystal violet (CV) dye adsorption. Herein, we introduced a facile method to produce a unique green adsorbent material from cellulose nanofibers (CNFs) via a nonsolvent assisted procedure using Meldrum's acid as an esterification agent to enhance the adsorption toward positively charged crystal violet dyes. Most of the surface modifications of cellulose nanofibers have been done using toxic organic solvents like pyridine, dimethyl acetate, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), etc. So far, this is the first report on the surface modification of cellulose nanofibers via a nonsolvent assisted procedure. Both CNF-based PVDF membranes were prepared by successive coating of modified and unmodified CNFs on to the surface of a PVDF electrospun membrane. All the demonstrated membranes showed high filtration capacity against the Fe2O3 nanoparticles. With the 10 mg/L of crystal violet (CV) aqueous solution, CV adsorption of PVDF electrospun membrane, and unmodified CNF-based PVDF membrane was around 1.368 and 2.948 mg/g of the membrane respectively, whereas it was 3.984 mg/g of the membrane by Meldrum's acid CNF-based PVDF membrane. The demonstrated Meldrum's acid modified CNF-based PVDF membrane was proven to be the efficient media that can concurrently eliminate the Fe2O3 nanoparticles and CV dyes from the water. The investigation into the surface chemistries of cellulose nanofibers beyond the adoption of toxic solvents can enhance the economic usefulness of the process and also yield a new ecofriendly adsorbent material that is agreeable to adsorbing various toxic pollutants

Mechanically Robust Antibacterial Nanopapers Through Mixed Dimensional Assembly for Anionic Dye Removal

There is a piqued interest in development of biobased sorbents for water treatment. Here in we reported, the fabrication of mechanically strong nanopapers by mixed dimensional assembly of 1D Cellulose nanofibers and 2D amino functionalized graphene oxide for water treatment. The fabricated amino functionalized GO/ cellulose nanofiber (AMGO-CNF) nanopaper showed superior antibacterial resistance towards Escherichia coli MTCC 1610 and Klebsiella due to the enhanced surface roughness which was confirmed from SEM and AFM studies. The amino group present in the AMGO enhanced the adsorption efficiency of the nanopaper towards methyl orange dye. The fabricated nanopaper showed an adsorption of 11.05 mg/gm 30 mg/L concentration at pH 2. Maximum adsorption was observed at pH 2 which was due to protonation of amine group. Moreover, the fabricated membrane showed excellent hydrolytic stability which can be corroborated to the surface roughness and reduced hydrophilicity. The investigation into the surface chemistries of cellulose nanofibers beyond the adoption of toxic solvents can enhance the economic usefulness of the process and yield a new eco-friendly adsorbent material that is agreeable to adsorbing various toxic pollutants