Cellulose Surface Research Articles

Treatment of heavy metal ions-polluted water into drinkable water: Capture and recovery of Pb2+ by cellulose@CaCO3 bio-composite filter via spatial confinement effect

A bio-composite of cellulose@CaCO3 (Cel@CaCO3) has been prepared via a facile precipitation reaction route, in anticipation of solving the toxic lead ion pollution problem and satisfying the sustainable development. The microstructures along with the morphology were characterized by XRD, FT-IR, SEM and TEM. It is found that CaCO3 forms the hydrogen bonding with cellulose in the composite, which makes it cover on the cellulose fibers. This would construct a suitable micro-environment for the Pb2+ capture and removal due to the spatial confinement effect. The high performance has been achieved with the up-taken capacity of 602.3 mg·g−1. When treating the wastewater with the Pb2+ concentration less than 50 mg·g−1, almost 100 % removal rate was obtained only within 10 min. The Pb2+ ions were trapped on the surface of cellulose and appeared as the form of PbCO3. Consequently, the complete separation and recovery would be accomplishable without the secondary pollution, for the spent bio-composite filter was removed easily and conveniently. Notably, the treated water met the drinkable criterion. The roles of cellulose and removal mechanism have also been explained in details.

A sensitive dual mode turn-on fluorescence and colorimetric nanosensor for ultrasensitive detection of trace amount of gluten proteins in bread products based on crystalline nano cellulose and gold nanoparticles

In this work, Gold nanoparticles (AuNPs) encapsulated in the surface of crystalline nano cellulose grafted poly citric acid (CNC-g-PCA) and CNC-g-PCA/Au nanocomposite were synthesized successfully that exhibited stable and intense fluorescence property in aqueous buffer. A dual-mode nanosensor is reported with both colorimetric and fluorimetric readout based on citrate-protected AuNPs for discriminative detection of gluten proteins. The proposed sensing system consists of AuNPs and fluorescent CNCs, where CNCs function as a fluorimetric reporter and AuNPs serve a dual function as a colorimetric reporter and fluorescence quencher. The mechanism of the reported dual-mode nanosensor is based on two distance-dependent phenomena, the color change of AuNPs and FRET. The presence of gluten proteins can reverse the process by enlarging the inter-particle distance between AuNPs and CNCs and recovering the fluorescence emission of CNC. The linear range was 0.05 to 0.40 μgmL−1 for UV–vis spectroscopy and 0.017 to 0.298 μgmL−1 for fluorescence spectroscopy, The limit of detection was 4.43 ± 0.019 ngmL−1 for UV–vis spectroscopy and 3.13 ± 0.033 ngmL−1 for fluorescence spectroscopy (n = 6). The fabricated nanosensor was applied to the gluten analysis in gluten-free bread successfully.

Visual design of high-density polyethylene into wood plastic composite with multiple desirable features: A promising strategy for plastic waste valorization

Plastics waste represents an alarming pollution to the world due to its high production volume, strong biological and chemical stability hence difficult to be decomposed. Plastic waste has currently been disposed of in an unsatisfactory manner, resulting in secondary pollution of the environment being inevitable. This study demonstrates the use of plastic waste as feedstock to produce wood plastic composites as a promising strategy to reuse plastic waste. The existing production methods for wood plastic composite are complex, cost ineffective, and often yield the product with low mechanical properties. Here, we report a one-step hot molding method as an alternative to prepare high-performance wood plastic composites using poplar veneer and recycled high density polyethylene (HDPE). The resulted composite shows enhanced hydrogen bonding between cellulose and molecular crosslinking networks which have led to the carbonized lignin coated on the surface of cellulose. The composite also possesses of high strength (tensile strength 198.9 MPa), waterproof, corrosion resistance, heat insulation and flame retardancy. Overall, the composite prepared can be used in construction and furniture, thus demonstrating an effective approach to re-utilize plastic waste.

Molecular insights on the crystalline cellulose-water interfaces via three-dimensional atomic force microscopy.

Cellulose, a renewable structural biopolymer, is ubiquitous in nature and is the basic reinforcement component of the natural hierarchical structures of living plants, bacteria, and tunicates. However, a detailed picture of the crystalline cellulose surface at the molecular level is still unavailable. Here, using atomic force microscopy (AFM) and molecular dynamics (MD) simulations, we revealed the molecular details of the cellulose chain arrangements on the surfaces of individual cellulose nanocrystals (CNCs) in water. Furthermore, we visualized the three-dimensional (3D) local arrangement of water molecules near the CNC surface using 3D AFM. AFM experiments and MD simulations showed anisotropic water structuring, as determined by the surface topologies and exposed chemical moieties. These findings provide important insights into our understanding of the interfacial interactions between CNCs and water at the molecular level. This may allow the establishment of the structure-property relationship of CNCs extracted from various biomass sources.

(Invited) Surface Modification to Control Wetting and Adhesion of Aqueous Solutions

rf plasmas and electrochemical treatments have been used extensively for thin film deposition and etching in the fabrication of microelectronic and photonic devices. These methods can be applied to non-traditional substrates (e.g., paper and stainless steel) to alter surface and bulk properties to create (i) paper-based analytical devices with application to microfluidic devices, and (ii) antibacterial structures on stainless steel. Two examples will be described. First, the effects of plasma-based oxygen etching of cellulose surfaces followed by plasma-enhanced fluorocarbon film deposition will be described and shown to control wetting and adhesion of water droplets. These process steps can also be used to form fully enclosed hydrophilic channels in bulk paper and thereby allow microfluidic device fabrication on inexpensive and renewable substrates. Electrochemical etching of stainless steel creates micro- and nano-structures on stainless steel surfaces that repel water and bacteria. These surfaces have potential applications in orthopedic implants and consumer metal products prone to bacterial contamination.

Prediction Model of Bubble Formation in Oil-Paper Insulation Based on the ITBE Envelope

Due to rapid temperature rise and insulation moisture, bubbles can generate in the oil-paper insulation of oil-immersed power transformers, which can reduce the dielectric strength of oil-paper insulation and even bring about the risk of insulation breakdown. In order to accurately evaluate the conditions of bubble formation, the physical process of bubble formation in oil-paper insulation is studied in this article. Considering the effects of water vaporization, gas dissolution in oil, and moisture migration on bubble formation, a bubble formation prediction model is constructed. Based on Henry’s law, the dissolution equilibrium of gas in oil is taken into consideration and the upper boundary of the initial temperature of bubble effect (ITBE) envelope is obtained in this model. Based on the moisture equilibrium in oil-paper insulation, the bubble formation process caused by the emergence and rapid evaporation of free water is analyzed, and then, the lower boundary of the ITBE envelope is obtained in this model. The model results show that the moisture content of the pressboard and the presence of free water have a great impact on ITBE. Specifically, the higher the moisture content, the lower the ITBE value. In addition, with the further increase of moisture content, the upper and lower boundaries of the ITBE envelope gradually tend to be the same. However, once free water is present on the surface of cellulose, ITBE decreases rapidly to below 120 °C. The model built in this article is of great significance to study the temperature limit of the power transformer. Hence the ITBE envelope can provide an important theoretical reference for reducing the risk of bubble formation during power transformer operation.

Efficient utilization of waste wheat straw through humic acid and ferric chloride co-assisted hydrothermal pretreatment for fermentation to produce bioethanol

The adsorbed ash and lignin contained in waste wheat straw (WWS) have been the essential factors restricting its high-value utilization in biorefinery. Hence, humic acid (HA) and FeCl3 as the additives of hydrothermal pretreatment were applied to simultaneously enhance the removal of lignin and eliminate the acid buffering of ash in WWS, respectively. The results showed that the xylan and lignin removal of WWS pretreated with 10 g/L HA and 20 mM FeCl3 could be efficiently increased from 61.4% to 72.9% and from 14.7% to 38.7%, respectively. The enzymatic hydrolysis efficiency and ethanol yield of WWS were increased this way from 44.4% to 82.7% and from 20.55% to 36.86%, respectively. According to the characterization of WWS, the synergistic interaction between HA and FeCl3 was beneficial to the cellulose accessibility and surface lignin area of WWS changed in positive directions, leading to the improvement of hydrolysis efficiency.

Immobilization of Solvatochromic Dyes on Transparent Cellulose Films: an Improved Method for the Study of Homeopathic Potencies.

Highly diluted and succussed solutions (homeopathic potencies) have been shown to interact with a wide range of solvatochromic dyes based on changes in their UV-visible spectra. Studies so far have involved free dyes in solution, but there is a pressing need to find ways to investigate the potency-dye interaction using isolated dye molecules to ask more searching physico-chemical questions regarding the fundamental nature of potencies. The aims of the present study have been to look for ways to covalently immobilize solvatochromic dyes onto transparent cellulose films and hence be in a position to investigate dye-potency interactions without the complication of dye-dye interactions, including dye aggregation, which can occur with free dyes in solution. To date, a total of nine different dyes have been immobilized on cellulose films using epoxide activation of hydroxyl groups on the cellulose surface. Using this method, studies have begun looking at the time course of potency action on one of these immobilized dyes, Brooker's merocyanine. Results show that the interaction of Arsenicum 10M with this dye consists of three phases-an initial growth phase, a sustained plateau of interaction, and a final decline phase lasting several days. A method has been developed that successfully immobilizes solvatochromic dyes onto transparent cellulose film. These films can then be used in a spectrophotometer to study at a much more detailed level how potencies interact with dyes compared with using free dyes in solution. Results indicate that the information gained in this way provides new insights regarding the fundamental nature of potencies. Specifically, studies using immobilized Brooker's merocyanine with Arsenicum 10M reveal that the lifetime of the potency is much longer than expected and that its action consists of three distinct phases, suggesting a resonant interaction with the dye. How resonant interaction might help to explain the clinical action of potencies is discussed.

Cellulose-based films with enhanced load of nitrogen containing heterocycles: The impact on the surface morphology and proton conductivity

Nitrogen-containing heterocycles and cellulose are a promising pair of materials studied for use as polyelectrolytic membranes in fuel cells. However, the effect of the amount of heterocycle applied to the cellulosic substrate on the proton conductivity value is yet unknown. In order to provide new insights, in this paper we investigated the proton conductivity of three types of cellulose-based films that contain varying amounts of 1-hydroxybenzotriazole (HBT), a model heterocycle, in close correlation with other film surface properties such as X-ray diffraction, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Furthermore, the effects of changing the kind of cellulosic surface on mechanical characteristics were assessed.

Immobilisation of Solvatochromic Dyes on Transparent Cellulose Films; an Improved Methodology for the Study of Homeopathic Potencies.

Abstract
 Background Highly diluted and succussed solutions (homeopathic potencies) have been shown to interact with a wide range of solvatochromic dyes based on changes in their UV-visible spectra. Studies so far have involved free dyes in solution, but there is a pressing need to find ways to investigate the potency-dye interaction using isolated dye molecules in order to ask more searching physico-chemical questions regarding the fundamental nature of potencies.
 Aims and Methods The aims of the present study have been to look for ways to covalently immobilise solvatochromic dyes onto transparent cellulose films and hence be in a position to investigate dye-potency interactions without the complication of dye-dye interactions, including dye aggregation, which can occur with free dyes in solution.
 Results To date a total of nine different dyes have been immobilised on cellulose films using epoxide activation of hydroxyl groups on the cellulose surface. Using this methodology studies have begun looking at the time course of potency action on one of these immobilised dyes, Brooker’s merocyanine. Results show that the interaction of Arsenicum 10M with this dye consists of three phases – an initial growth phase, a sustained plateau of interaction and a final decline phase lasting several days. 
 Conclusions A methodology has been developed that successfully immobilises solvatochromic dyes onto transparent cellulose film. These films can then be used in a spectrophotometer to study at a much more detailed level how potencies interact with dyes compared with using free dyes in solution. Results indicate that the information gained in this way provides new insights regarding the fundamental nature of potencies. Specifically, studies using immobilised Brooker’s merocyanine with Arsenicum 10M reveal that the lifetime of the potency is much longer than expected and that its action consists of three distinct phases, suggesting a resonant interaction with the dye.

Significant enhancement of electrical conductivity of conductive cellulose derived from bamboo and polypyrrole

Cellulose fiber was successfully prepared from bamboo waste. It was chemically purified by alkali treatment at ambient condition. After that, conductive cellulose was successfully prepared. Polypyrrole was formed due to the presence of FeCl3. It was coated on the surface of purified cellulose. It was remarkable to note that N-H stretching was observed by Fourier transform infrared. No significant change of crystallinity was observed by X-ray diffraction. Thermogravimetric analysis reported that composites were thermally stable up to 200 °C. Scanning electron microscope reported the smoothness of surface. The existence of polypyrrole was found in the porosity between cellulose networks. Energy dispersive analysis and CHN analysis illustrated the presence of ferrous and nitrogen atoms, respectively. The electrical conductivity was enhanced with respect to amount of polypyrrole. It was remarkable to note that polypyrrole coated onto surface of cellulose derived from bamboo exhibited the excellent properties as a candidate for the flexible electronic substrate.

Cellulose Iβ microfibril interaction with pristine graphene in water: Effects of amphiphilicity by molecular simulation

Graphene-cellulose interactions have considerable potential in the development of new materials. In previous computational work (Biomacromolecules2016, 16, 1771), we predicted that the model 100 hydrophobic surface of cellulose interacted favourably with pristine graphene in aqueous solution molecular dynamics simulations; conversely, a model of the hydrophilic 010 surface of cellulose exhibited progressive rearrangement to present a more hydrophobic face with the graphene, with weakened hydrogen bonds between cellulose chains and partial permeation of water. Here, we extend this work by simulating the interaction in aqueous solution of the amphiphilic 110 surface of a cellulose Iβ microfibril model, comprising 36 chains of 40 glucosyl residues, with an infinite sheet of pristine graphene. This face of the microfibril is of intermediate hydrophilicity and progressively associates with graphene over replicate simulations. As cellulose chains adhere to the graphene surface, forming interactions via its CH and OH groups, we observe a degree of local and global untwisting of the microfibril. Complementary rippling of the graphene surface is also observed, as it adapts to interaction with the microfibril. This adsorption process is accompanied by increased exclusion of water between cellulose and graphene although some water localises between chains at the immediate interface. The predicted propensity of a cellulose microfibril to adsorb spontaneously on the graphene surface, with mutual structural accommodation, highlights the amphiphilic nature of cellulose and the types of interactions that can be harnessed to design new graphene-carbohydrate biopolymer materials.

Citrate-mediated impregnation of silver nanoparticles for durable antibacterial cellulosic fabric

PurposeThe purpose of this study is to apply silver nanoparticles on the cellulosic fabric via a green cross-linking approach to obtain antibacterial textiles. The cellulosic fabrics may provide an ideal enclave for microbial growth due to their biodegradable nature and retention of certain nutrients and moisture usually required for microbial colonization. The application of antibacterial finish on the textile surfaces is usually done via synthetic cross-linkers, which, however, may cause toxic effects and halt the biodegradation process.Design/methodology/approachHerein, we incorporated citrate moieties on the cellulosic fabric as eco-friendly crosslinkers for the durable and effective application of nanosilver finish. The nanosilver finish was then applied on the citrate-treated cellulosic fabric under the pad-dry-cure method and characterized the specimens for physicochemical, textile and antibacterial properties.FindingsThe results expressed that the as-prepared silver particles possessed spherical morphology with their average size in the nano range and zeta potential being −40 ± 5 mV. The results of advanced analytical characterization demonstrated the successful application of nanosilver on the cellulosic surface with appropriate dispersibility.Practical implicationsThe nanosilver-treated fabric exhibited appropriate textile and comfort and durable broad-spectrum antibacterial activity.Originality/valueThe treated cellulosic fabric expressed that the cross-linking, crystalline behavior, surface chemistry, roughness and amphiphilicity could affect some of its comfort and textile properties yet be in the acceptable range for potential applications in medical textiles and environmental sectors.

Deconstruction of pineapple peel cellulose based on Fe2+ assisted cold plasma pretreatment for cellulose nanofibrils preparation

An effective method based on Fe2+ assisted cold plasma (CP) to pretreat pineapple peel cellulose for the preparation of cellulose nanofibrils (CNF) was proposed in this study. The mechanism underlying Fe2+ assisted CP pretreatment based on the structural changes of cellulose was investigated. Results showed that the cellulose preabsorbed Fe2+, followed by 60 min of CP treatment, and then was nanofibrillated into CNF via ultrasonication. Fe2+ assisted CP treatment exhibited strong capacity to significantly decrease the degree of polymerization of cellulose and to enhance electrostatic repulsion of fibrils. Furthermore, the roughness and breakage were observed on the surface of pretreated cellulose. The content of inter-molecular hydrogen bonds and average crystallite size (Dhkl) also decreased significantly. The current results provided useful fundamental insights into Fe2+ assisted CP and cellulose interaction, which should be beneficial to developing new pretreatment methods for disintegrating cellulose into CNF.

Influence Of Dewaxing on Mechanical properties of kapok fiber-reinforced polymer composite

The low density, lightweight, easy processing and biodegradability nature of Natural fiber-reinforced polymer composite have gained enough attention from many researchers and scientists. Kapok Fiber (Ceiba pentandra) is a natural cellulosic fiber have a hollow microtubular structure and a high degree of hollowness. The hand lay-up technique has been adopted for kapok fiber-reinforced epoxy polymer composite fabrication with different fiber loading(2, 3, 4, 5, 6 and 7 wt %). The mechanical strength of kapok fiber-reinforced polymer epoxy composite is investigated through the flexural and tensile test. The best flexural and tensile performance is observed at 5 wt% loading of kapok fiber. To increase compatibility between fiber and epoxy matrix dewaxing process is adopted. The effect of dewaxing on cellulose crystallinity, crystallinity size, surface morphology, elemental composition and functional groups of fiber are studied. The roughness of the fiber surface increases after dewaxing due to the partial removal of non-cellulosic compounds like lignin, pectin, wax and some oily substances. The increase in fiber surface roughness and cellulose crystallinity index by chemical treatment made a strong interlocking at the fiber-matrix interface. The effect of dewaxing on mechanical strength is also studied to fabricate the composite for the benefit of society.

Poly(dopamine)-modified microcrystalline cellulose,a green reinforcing filler for natural rubber latex with high performance

ABSTRACT The presence of a large number of reactive -OH groups on the surface of the microcrystalline cellulose (MCC) causes the MCC to easily agglomerate together due to hydrogen bonding, reducing the dispersion of the MCC in the NRL matrix. At the same time, the poor interfacial compatibility between the hydrophilic MCC and the hydrophobic NRL substrate does not achieve a good reinforcement effect, thus limiting to a certain extent the application of MCC in rubber substrates. The surface modification of MCC by poly(dopamine) (PDA) for improving the performance of rubber composites and broadening the application of MCC in NRL matrix, and improving the dispersibility and interfacial interaction of nanofillers in natural rubber latex (NRL) composites was studied. We report the effects of the MCC/PDA ratios on the vulcanization characteristics, the Payne effect, and the mechanical properties of the developed composites. These facts exhibit that not only the processing properties but also the mechanical performance of NRL/MCC/PDA are better than those of the NRL/MCC composites. This study reports an efficient approach to improving the interfacial interaction of the nanocomposite. Based on this, as a green reinforcing filler, MCC modified with PDA shows great potential in reinforcing NRL composites. Furthermore, a simple dip-coating method was used to modify the surface of MCC with dopamine. FTIR, TGA, and XRD confirmed the interaction between PDA and MCC.

Effects of Fluorine-Based Modification on Triboelectric Properties of Cellulose.

The hydroxyl groups on the cellulose macromolecular chain cause the cellulose surface to have strong reactivity. In this study, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PDOTES) was used to modify cellulose to improve its triboelectric properties, and a triboelectric nanogenerator (TENG) was assembled. The introduction of fluorine groups reduced the surface potential of cellulose and turned it into a negative phase, which enhanced the ability to capture electrons. The electrical properties increased by 30% compared with unmodified cellulose. According to the principles of TENGs, a self-powered human-wearable device was designed using PDOTES-paper, which could detect movements of the human body, such as walking and running, and facilitated a practical method for the preparation of efficient wearable sensors.

Metal-organic frameworks decorated wood aerogels for efficient particulate matter removal

The severe indoor/outdoor air contamination caused by hazardous particulate matters (PMs) has a devastating impact on the environment and human health. Herein, air filters fabricated from delignified wood aerogels and metal–organic frameworks (MOFs) were used for PM removal. Two specially designed MOFs (i.e. Zn-based ZIF-L and Zr-based UiO-66-NH2) were deposited into a highly porous wood matrix through in situ growth approach. The MOF crystals are attached tightly to the highly available cellulose surface groups and distributed uniformly. The integration of MOFs can regulate the aerogel morphology and surface property, leading to enhanced PM removal performance. Bare wood aerogels beard removal efficiencies of 70.7% and 75.0% for PM2.5 and PM10, with a low-pressure drop of 15 Pa. By contrast, ZIF-L decorated wood aerogels exhibited PM2.5 and PM10 removal efficiencies of 97.6% and 99.5%, respectively, which are ascribed to the increased interception/impaction of PMs with the positively charged ZIF-L layer. While UiO-66-NH2 functionalized wood aerogels demonstrated PM2.5 and PM10 removal efficiencies of 96.4% and 98.9% because of the hierarchical filter matrix and the presence of polar –NH2 groups. Moreover, MOF modified wood aerogels can be easily regenerated and superior reusability can be achieved. This work provides an effective and economic strategy for the preparation of air filters from renewable materials.

Enzyme Synergy in Transient Clusters of Endo- and Exocellulase Enables a Multilayer Mode of Processive Depolymerization of Cellulose.

Biological degradation of cellulosic materials relies on the molecular-mechanistic principle that internally chain-cleaving endocellulases work synergistically with chain end-cleaving exocellulases in polysaccharide chain depolymerization. How endo–exo synergy becomes effective in the deconstruction of a solid substrate that presents cellulose chains assembled into crystalline material is an open question of the mechanism, with immediate implications on the bioconversion efficiency of cellulases. Here, based on single-molecule evidence from real-time atomic force microscopy, we discover that endo- and exocellulases engage in the formation of transient clusters of typically three to four enzymes at the cellulose surface. The clusters form specifically at regular domains of crystalline cellulose microfibrils that feature molecular defects in the polysaccharide chain organization. The dynamics of cluster formation correlates with substrate degradation through a multilayer-processive mode of chain depolymerization, overall leading to the directed ablation of single microfibrils from the cellulose surface. Each multilayer-processive step involves the spatiotemporally coordinated and mechanistically concerted activity of the endo- and exocellulases in close proximity. Mechanistically, the cooperativity with the endocellulase enables the exocellulase to pass through its processive cycles ∼100-fold faster than when acting alone. Our results suggest an advanced paradigm of efficient multienzymatic degradation of structurally organized polymer materials by endo–exo synergetic chain depolymerization.

Iridium-Functionalized Cellulose Microcrystals as a Novel Luminescent Biomaterial for Biocomposites

Microcrystalline cellulose (MCC) is an emerging material with outstanding properties in many scientific and industrial fields, in particular as an additive in composite materials. Its surface modification allows for the fine-tuning of its properties and the exploitation of these materials in a plethora of applications. In this paper, we present the covalent linkage of a luminescent Ir-complex onto the surface of MCC, representing the first incorporation of an organometallic luminescent probe in this biomaterial. This goal has been achieved with an easy and sustainable procedure, which employs a Bronsted-acid ionic liquid as a catalyst for the esterification reaction of -OH cellulose surface groups. The obtained luminescent cellulose microcrystals display high and stable emissions with the incorporation of only a small amount of iridium (III). Incorporation of MCC-Ir in dry and wet matrices, such as films and gels, has been also demonstrated, showing the maintenance of the luminescent properties even in possible final manufacturers.