Surface Of Cellulose Fibers Research Articles

Synthesis and application of hydrazono-imidazoline modified cellulose for selective separation of precious metals from geological samples

A new hydrazono-imidazoline modified cellulose (HIMC) was synthesized for selective recovery of Pt(IV), Pd(II) and Au(III) from geological samples. Cellulose was oxidized by periodate and was further functionalized with hydrazono-imidazoline moieties to afford N-donor chelating fibers. Scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 physisorption, elemental analysis, and energy-dispersive X-ray spectroscopy (EDX) were used for characterization. Introducing the hydrazono-imidazoline groups at the surface of cellulose fibers did not alert their ordered structure and crystallinity, as indicated by XRD and SEM results. Factors affecting the adsorption were systematically investigated. Under the optimized conditions, the HIMC sorbent exhibited high adsorption capacities of 105, 88 and 75 mg g−1 for Pt(IV), Pd(II) and Au(III), respectively. Besides, the metal ion adsorption process fitted by pseudo-second-order kinetic model and Langmuir adsorption isotherm. These results highlight the applicability of this carbohydrate-based sorbent for the selective recovery of precious metals from various matrices.

Boosting electrical properties of flexible PEDOT/cellulose fiber composites through the enhanced interface connection with novel combined small-sized anions

Rapid development of flexible electronics has raised the demand for renewable conductive materials. Biomass-derived cellulose fibers (CFs) are very promising candidates due to their outstanding advantages. In this paper, flexible, lightweight and freestanding biomaterial with high electrical conductivity was prepared via in situ chemical polymerization process using 3,4-ethylenedioxythiophene (EDOT) and CFs. In order to improve the performance of PEDOT/CFs, novel combined small-sized anion doping agents, sulphosalicylic acid (SSA) and sodium benzenesulfonate (SBS), were adopted to construct a well-organized conducting layer. The obtained PEDOT layer possessed good crystallinity and high doping level and was uniformly coated onto the surface of CFs through the dopant-dependent interface. The PEDOT:SSA-SBS/CFs exhibited electrical conductivity as high as 472 S/m and the mass loading was up to 1.92 mg/cm2. Moreover, the flexible biomaterial displayed favorable electrochemical stability. Hence, the results presented here provide a new way to produce highly conducting and flexible biomaterial.

Study of wheat straw delignification in a rotary-pulsation apparatus

This paper presents the results of studies of isolation lignin and hemicelluloses efficiency during the pre-treatment of wheat straw for hydrolysis in a rotary-pulsation apparatus. The pre-treatment of lignocellulosic raw materials for hydrolysis is a necessary step in the second-generation bioethanol production technology. The lignocellulose complex is destroyed during this process, and this allows hydrolytic enzymes access to the surface of cellulose fibers. The pre-treatment is the most energy-consuming stage in bioethanol production technology, since it usually occurs at high temperature and pressure for a significant time. One of the ways to improve the efficiency of this process is the use of energy-efficient equipment that allows intensifying heat and mass transfer. An example of such equipment is a rotary-pulsation apparatus, which are effective devices in stirring, homogenization, dispersion technologies, etc. The treatment of wheat straw in a rotary-pulsation apparatus was carried out under atmospheric pressure without external heat supply at solid/water ratios of 1:10 and 1:5 in the presence of alkali. It was determined that the treatment of the water dispersion of straw at ratio of 1:10 due to the energy dissipation during 70 minutes leads to the release of 42 % of lignin and 25.76 % of easily hydrolyzed polysaccharides. Changing the solid / water ratio from 1:10 to 1:5 leads to an increase in the yield of lignin and easily hydrolyzed polysaccharides to 58 and 33.38 %, respectively.

Laminated superwetting aerogel/membrane composite with large pore sizes for efficient separation of surfactant-stabilized water-in-oil emulsions

Although superwetting filtration membranes have been widely used, they suffer from the disadvantages of low flux and membrane fouling caused by the nanoscale pore size. Herein, a laminated cellulose aerogel/membrane composite with large pore size is fabricated via combining facile freeze-drying and hydrophobic modification using cellulose fibers as building blocks. An ultrathin silanization coating layer on cellulose fibers surface is constructed via directly coupling alkoxysilane and endows the composite with excellent superhydrophobicity (161°) and superoleophilicity (0°). Upon contact with a water-in-oil emulsion, the aerogel layer causes the micrometer-sized water droplets to coalesce. The coalesced water droplets are then repelled by the membrane layer with large pore size, achieving ultrafast gravity-driven separation with high separation efficiency (99.5%) and separation flux (12890 L m−2 h−1). Moreover, the composite exhibits ease to cycle and good usability. The outstanding performance of composite highlights its potential applications in the field of oil related industry.

Highly flame retardant zeolitic imidazole framework-8@cellulose composite aerogels as absorption materials for organic pollutants

In the current study, Zeolitic Imidazole Framework-8 (ZIF-8) was in situ grown on the surface of cellulose fibers and the ZIF-8@cellulose composite aerogels were fabricated by a freeze-drying method. The flame-retardant, thermal and mechanical characteristics of the cellulose-based aerogels were investigated. SEM images indicated that ZIF-8 was evenly deposited on the surface of the cellulose fibers in the aerogel owing to formation of hydrogen bonding with cellulose molecules. The addition of ZIF-8 enhanced thermal stability and flame retardancy of the host cellulose aerogel. The peak of heat release rate of the ZIF-8@cellulose-3 composite aerogel exhibited a drastic decline from 128 W g−1 to 63 W g−1 and the total heat release from 25.9 kJ g−1 to 14.8 kJ g−1. In the UL-94 vertical burning test, the samples showed self-extinguishing behavior. Additionally, ZIF-8 induced a dramatic enhancement in the mechanical properties of the host cellulose. Specifically, the compressive stress of the ZIF-8@cellulose composite aerogel showed a significant increase from 0.45 to 34.80 MPa. Moreover, the ZIF-8@cellulose composite aerogel can selectively remove the organic pollutants from water and adsorb a wide range of liquid oils with considerable capacities. The current study presented a feasible approach to synthesis of strong and flame-retardant cellulose-based aerogels for waste water purification.

Reinforcing agents based on cellulose fibers modified by insertion of end-alkyl groups obtained from pyrolytic bio-oil of sugarcane bagasse

Modification of cellulose fibers is a promissory alternative for the production of new composite materials, but the high hydrophilicity of cellulose limits its use as a reinforcing agent in the making of olefin-based composites. The aim of this research was to develop reinforcing agents based on cellulose fibers modified by insertion of end-alkyl groups from pyrolytic bio-oil (PBO). For that, PBO of sugarcane bagasse was obtained and characterized by several techniques including gas chromatography coupled to mass spectrometry. Later, the surface of cellulose fibers was activated using methylene-bis-isocyanate and modified using acetic acid, formic acid, and PBO. Results show that the modification of cellulose surface is possible by the use of PBO at low temperature obtaining results like to those obtained when organic acids are used.

Analysis of interfacial nanostructure and interaction mechanisms between cellulose fibres and calcium silicate hydrates using experimental and molecular dynamics simulation data

Understanding the effects of cellulose fibre on the nanostructure of and adhesion energy at the cellulose fibre-calcium silicate hydrate (C-S-H) interface is essential for designing high-performance cement-based composites (CBCs). Therefore, the chemical structure of cellulose fibre surface and microstructure of the fibre-cement matrix interface were investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Molecular dynamics (MD) simulations were used to study the adhesion energy and nanostructure at the cellulose fibre-(C-S-H) interface by comparing crystalline Iβ and amorphous celluloses (AC). The results revealed that the adhesion energy at the AC-(C-S-H) interface was approximately 35% greater than that at Iβ-(C-S-H) interface. Given that the AC configuration was disordered and presented greater deformation than Iβ, the AC-(C-S-H) interface was denser than the Iβ-(C-S-H) interface. Electrostatic interactions between OH groups and Ca2+ ions caused the Ca2+ in C-S-H to migrate towards the interface; the Ca2+ ions exhibit a bridging effect at the interface. Additionally, the OH groups in the cellulose fibre and C-S-H could also interact with each other via hydrogen bonding. The electrostatic and hydrogen bonds increased the interfacial adhesion energy, which was beneficial for improving the performance of cellulose fibre-reinforced CBCs.

Quantifying cellulose accessibility during enzyme-mediated deconstruction using 2 fluorescence-tagged carbohydrate-binding modules

Two fluorescence-tagged carbohydrate-binding modules (CBMs), which specifically bind to crystalline (CBM2a-RRedX) and paracrystalline (CBM17-FITC) cellulose, were used to differentiate the supramolecular cellulose structures in bleached softwood Kraft fibers during enzyme-mediated hydrolysis. Differences in CBM adsorption were elucidated using confocal laser scanning microscopy (CLSM), and the structural changes occurring during enzyme-mediated deconstruction were quantified via the relative fluorescence intensities of the respective probes. It was apparent that a high degree of order (i.e., crystalline cellulose) occurred at the cellulose fiber surface, which was interspersed by zones of lower structural organization and increased cellulose accessibility. Quantitative image analysis, supported by 13C NMR, scanning electron microscopy (SEM) imaging, and fiber length distribution analysis, showed that enzymatic degradation predominates at these zones during the initial phase of the reaction, resulting in rapid fiber fragmentation and an increase in cellulose surface crystallinity. By applying this method to elucidate the differences in the enzyme-mediated deconstruction mechanisms, this work further demonstrated that drying decreased the accessibility of enzymes to these disorganized zones, resulting in a delayed onset of degradation and fragmentation. The use of fluorescence-tagged CBMs with specific recognition sites provided a quantitative way to elucidate supramolecular substructures of cellulose and their impact on enzyme accessibility. By designing a quantitative method to analyze the cellulose ultrastructure and accessibility, this study gives insights into the degradation mechanism of cellulosic substrates.

Natural Cellulose Derived Nanocomposites as Anodic Materials for Lithium-Ion Batteries.

Bio-inspired synthetic method provides an effective shortcut to fabricate functional nanostructured materials with specific morphologies and designed functionalities. Natural cellulose substances (e. g., commercial laboratory cellulose filter paper) possesses unique three-dimensionally cross-linked porous structures and abundant functional groups for the functional modification on the surfaces. The deposition of metal oxide gel film on the surfaces of the cellulose nanofibers is facilely to be achieved through the surface sol-gel process, resulting in metal oxide replicas of the initial cellulose substance or metal-oxide/carbon nanocomposites. Moreover, the as-deposited metal oxide gel films coated on the cellulose fiber surfaces provide ideal platforms for the further formation of specific functional assemblies, and eventually to the corresponding nanocomposite materials. Based on this methodology, various nanostructured composites were prepared and employed as anodic materials for lithium-ion batteries, including metal-oxides-based (such as SnO2 , TiO2 , MoO3 , Fex Oy , and SiO2 ) and Si-based composites, as summarized in this personal account. Benefiting from the unique hierarchically porous network structures and the synergistic effects among the composite components of the anodic materials, the transfer of electrons/ions is accelerated and the structural stability of the electrode is enhanced, leading to the improved lithium storage performances and promoted cycling stability.

Evaluating the degree of molecular contact between cellulose fiber surfaces using FRET microscopy

The degree of molecular contact, i.e. the contact area on the nanometer scale, between paper fibers is crucial for the van-der-Waals and hydrogen bond adhesion between the fibers and thus for the fiber-fiber bond strength. We apply Förster resonance energy transfer (FRET) to investigate the degree of contact in the distance range of 1–10 nm between pulp fiber bonds and between thin films. The FRET system with DCCH and FTSC as fluorescence dyes has been validated for spectrophotometry and for local imaging with widefield microscopy, using pHema thin films. Bonding between thin films can be detected with this system, however it has not been possible to achieve a significant FRET signal between bonded pulp fibers. Therefore, we conclude that in principle it is possible to quantify the degree of contact between two surfaces on the nanometer scale with the investigated FRET system. For further work on pulp fibers we recommend an exclusively surface active dyeing, as bulk dyeing massively deteriorates the signal to noise ratio which is likely the reason for the low FRET signal found in this work.Graphic

Conductive Regenerated Cellulose Fibers by Electroless Plating

Continuous metalized regenerated cellulose fibers for advanced applications (e.g., multi-functional composites) are produced by electroless copper plating. Copper is successfully deposited on the surface of cellulose fibers using commercial cyanide-free electroless copper plating packages commonly available for the manufacturing of printed wiring boards. The deposited copper was found to enhance the thermal stability, electrical conductivity and resistance to moisture uptake of the fibers. On the other hand, the chemistry involved in plating altered the molecular structure of the fibers, as was indicated by the degradation of their mechanical performance (tensile strength and modulus).

Facile Approach to Develop Hierarchical Roughness fiber@SiO2 Blocks for Superhydrophobic Paper.

Papers with nanoscaled surface roughness and hydrophobically modification have been widely used in daily life. However, the relatively complex preparation process, high costs and harmful compounds have largely limited their applications. This research aims to fabricate superhydrophobic papers with low cost and nontoxic materials. The surface of cellulose fibers was initially coated with a film of SiO2 nanoparticles via sol-gel process. After papermaking and subsequent modification with hexadecyltrimethoxysilane through a simple solution-immersion process, the paper showed excellent superhydrophobic properties, with water contact angles (WCA) larger than 150°. Moreover, the prepared paper also showed superior mechanical durability against 10 times of deformation. The whole preparation process was carried out in a mild environment, with no intricate instruments or toxic chemicals, which has the potential of large-scale industrial production and application.

The three-dimensional heterostructure synthesis of ZnO/cellulosic fibers and its application for rubber composites

Agglomeration of cellulosic fibers is the limiting factor in the fabrication of high-performance polymer composites. Here, we report a three-dimensional heterostructure of zinc oxide (ZnO)/cellulosic fiber hybrids to fabricate the multifunctional biomass rubber composites via the wet mixing method. The ultrasonic treatment and in-situ chemosynthesis method were used to incorporate ZnO particles on the surface of cellulosic fibers. The experimental results showed that ZnO particles with rod-like structures were grown on the surface of cellulosic fibers, and ultrasonic treated cellulosic fibers (UCF) could improve the aggregation and increase the growth content of ZnO particles from 16.5% to 23.2%. The composites microstructures showed that ZnO/UCF had a better dispersion and interface bonding than cellulosic fiber in natural rubber (NR) matrix. Moreover, ZnO/UCF/NR composites had higher tensile strength, stiffness, hydrophobic properties and antibacterial efficiency than pure NR. In view of the characterization of cellulosic fibers and inorganic particles, this three-dimensional structure hybrid would provide enormous opportunities to fabricate multifunctional biomass polymer composites.

Using cellulose fibers to fabricate transparent paper by microfibrillation

Fabricating transparent paper from cellulose nanofibers (CNFs) normally involves high energy or the use of expensive chemicals for the extraction of CNFs from cellulose fibers and time-consuming paper formation processes because of the slow filtration rate of CNFs. In this study, we reported a strategy for the fabrication of transparent paper using microfibrillated cellulose fibers (MFCFs), which were prepared by extracting nanosized fibrils from the cellulose fiber surfaces by a two-step refining process. The paper made from MFCFs has hierarchical structures of microsized fiber/nanosized fibril networks, where the microsized fiber skeletons are buried in the nanosized fibril networks. Consequently, the paper shows a light transmittance of 82.4% at 550 nm; this is comparable to the light transmittance (89.1%) of papers made from CNFs. Meanwhile, the filtration time of the paper made from MFCFs is less than 2 min, which is much shorter than the time (longer than 180 min) required for the formation of nanopaper made from commercial CNFs. In addition, the transparent paper made from MFCFs shows higher thermal stability, higher tensile strength, higher resistance to deformation, and more flexibility than the nanopaper made from commercial CNFs. This work provides a promising method for the manufacture of transparent paper from cellulose fibers.

Effective and simple one-step strategy for preparation of “clickable” cellulose modules: support to build antibacterial materials

An efficient and simple way to generate “clickable” cellulose modules called alkyne-functionalized cellulose fibers (ACFs) for click reaction was presented. This method is only based on one step reaction: propargyl methacrylate (PMA) with pendant alkynyl groups was grafted onto the surface of cellulose fibers (CFs) using ceric ammonium nitrate as the initiator in aqueous medium. This has been providing a new and versatile platform for the wide utilization of cellulose resources and creation of novel functional materials. The effect of process variables on grafting copolymerization of PMA was investigated and suitable preparation conditions were identified. The clickability of ACFs was evaluated by reacting with two azides. The antibacterial cellulose functional material was achieved through incorporation of a “clickable” handle (alkynyl groups) to cellulose fibers followed by rapid attachment of β-cyclodextrin with an azide tag using copper-catalyzed click reaction and loading with ciprofloxacin hydrochloride (CipHCl). Pure CFs and ACFs showed a little affinity to CipHCl, whereas click products (ACFs@Azide-β-CD) increased the loading amount dramatically because the equilibrium amount was higher than pure CFs and ACFs. Meanwhile, the release process of CipHCl from ACFs@Azide-β-CD was prolonged to reaches the equilibrium. The ACFs@Azide-β-CD loaded with CipHCl showed excellent antibacterial activity against Escherichia coli. The ACFs@Azide-β-CD loading CipHCl have considerably longer bacterial activity against E. coli compared to CFs and ACFs.

Study of ultraviolet sensing properties of ZnO nanoparticles grown on cellulose fibers

Abstract ZnO nanoparticles were grown on cellulose fiber surfaces with different precursor concentrations by a simple aqueous chemical method. The morphology and structure of the ZnO-cellulose nanocomposites were studied by scanning electron microscopy and X-ray diffraction, respectively. The ultraviolet sensitivity of the nanocomposites was observed by current-voltage measurement followed by time-resolved photocurrent study A ZnO-cellulose nanocomposite synthesized at 37.5 mM concentration of zinc nitrate hexahydrate had a higher UV sensitivity with faster response. Due to UV illumination, the photocurrent of the nanocomposite pellet increased from 2.251 × 10-8 A to 1.11 × 10-6 A in 8 s. The ON to OFF ratio (IUV/IDark) for this sample was found to be 49.31.

Immobilization of α-Fe2O3 nanoparticles on the cellulose surface: role of cellulose in tuning the microstructure and crystallographic phase

Nanoparticles of α-Fe2O3 of diameter ca. 15–130 nm were immobilized on the cellulose fiber surface by a single step in situ hydrothermal method carried out at 150 °C for 16 h. In the absence of cellulose, keeping all other experimental conditions same, nanoflakes of α-FeOOH having width of ca. 25 nm and length of ca. 250 nm were precipitated out. The immobilization of the α-Fe2O3 on the cellulose surface owing to the formation of the covalent bond between these two plays an important role in manipulating the nucleation of Fe(III) as α-Fe2O3. The non-existence of the covalent bond leads to the nucleation of the α-FeOOH. A plausible mechanism for the nucleation of α-Fe2O3 and α-FeOOH in the presence and absence of cellulose, respectively, has been proposed in the light of the evidence obtained from the FTIR, XPS and 13C CPMAS NMR investigations.

Mechanical Performance of Glass-Based Geopolymer Matrix Composites Reinforced with Cellulose Fibers.

Glass-based geopolymers, incorporating fly ash and borosilicate glass, were processed in conditions of high alkalinity (NaOH 10–13 M). Different formulations (fly ash and borosilicate in mixtures of 70–30 wt% and 30–70 wt%, respectively) and physical conditions (soaking time and relative humidity) were adopted. Flexural strength and fracture toughness were assessed for samples processed in optimized conditions by three-point bending and chevron notch testing, respectively. SEM was used to evaluate the fracture micromechanisms. Results showed that the geopolymerization efficiency is strongly influenced by the SiO2/Al2O3 ratio and the curing conditions, especially the air humidity. The mechanical performances of the geopolymer samples were compared with those of cellulose fiber–geopolymer matrix composites with different fiber contents (1 wt%, 2 wt%, and 3 wt%). The composites exhibited higher strength and fracture resilience, with the maximum effect observed for the fiber content of 2 wt%. A chemical modification of the cellulose fiber surface was also observed.

Improvement in adhesion of cellulose fibers to the thermoplastic starch matrix by plasma treatment modification

This work deals with provision and characterization of the biopolymer-based composites achieved by incorporation of cellulose fibers as the reinforcement within the glycerol plasticized matrix formed by thermoplastic cornstarch biopolymer. The function of starch-based polymers is limited due to poor mechanical properties. However, it is improved with forming a biocomposite of thermoplastic starch (TPS) as matrix and the cellulose fibers (CF) as reinforcement. The surface of cellulose fibers is successfully modified using the air plasma treatment with the aim of improving the matrix/fiber adhesion. The modified fibers are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TPS/CF composites are prepared using high friction and hot compression procedure. Tensile test results and SEM images of the fracture surfaces show significant improvement of adhesion between treated cellulose fibers and TPS matrix. Thermogravimetric analysis shows a considerable decomposition at approximately 250–350 °C. XRD proved the significant increase in crystallinity percentage of composites compared to TPS.

Cellulose-Derived Highly Porous Three-Dimensional Activated Carbons for Supercapacitors.

A novel “selective surface dissolution” (SSD) method was successfully utilized in previous research to prepare “all-polymer composites” aiming to structural applications. In the current study, this simple, cost-effective, and environmentally friendly method was employed for the first time to synthesize cellulose-derived highly porous three-dimensional (3D) activated carbon materials to assemble superior electrodes for supercapacitors. ZnCl2 aqueous solution was used to partially dissolve the surface of cellulose fibers. The partially dissolved cellulose I crystalline phase at the fiber surface can be consolidated into fibrillar cellulose polymorphs (e.g., cellulose II) which connects remaining fibers together. By a carefully controlled SSD method, a highly porous 3D cellulosic skeleton with interconnected bridge-like fibrillar linkages and hierarchical pore structures can be created. After carbonization, the 3D fiber construct with interconnected fibrillar linkages and hierarchical pore structures remains and highly porous activated carbons were obtained. The effects of various processing parameters (e.g., solvent concentration, immersion time, etc.) on the morphology of the as-formed activated porous carbons and their electrochemical performance as electrodes in supercapacitors were systematically investigated and discussed. It was concluded that the SSD method is a promising chemical approach to produce large-scale cellulose-derived activated porous carbons in an environmentally friendly manner.