Showing papers in "Cellulose in 2020"
TL;DR: French et al. as mentioned in this paper used the Rietveld method for cellulose crystallinity analysis, which includes the smaller peaks that are lost in what appears to be the background or amorphous scattering.
Abstract: Crystallinity analysis is important for practical reasons and related research can offer information on the nature of amorphous cellulose. Two papers in this issue mark a transition in general understanding of cellulose crystallinity analysis. First, a brief review of diffraction crystallinity methods. Several diffraction methods are used to analyze cellulose crystallinity (Thygesen et al. 2005; Park et al. 2010). The most prevalent, and by far the simplest, is the Segal peak height method (Segal et al. 1959). It had 4871 citations as of this writing, despite frequent use with no attribution or with only citations of secondary publications. Another approach, peak deconvolution, is more effort to carry out and to attribute. Perhaps Hermans and Weidinger (1948) were first to suggest that the area under diffraction peaks be divided by the total area. At present, conventional peak deconvolution involves curve fitting to the observed pattern with the individual visible peaks plus a very broad, but simple, e.g., Gaussian, peak for the amorphous material. Typically, general purpose curve-fitting software is used. A third method (Rietveld 1969 (16,400 citations); Young 1995) is used for general molecular structure determination of powders as well as occasionally for cellulose crystallinity. The Rietveld method also optimizes variables to fit a diffraction pattern, but it uses all of the diffraction peaks. Unlike peak deconvolution, the Rietveld method includes the smaller peaks that are lost in what appears to be the background or amorphous scattering. These smaller peaks can be visualized by calculating a diffraction pattern for an unrealistically large (100 nm) model cellulose crystal. Paul Scherrer (1918) showed that peaks are sharp when crystals are large, and broad when crystals are small. When the sharp and separated calculated peaks are broadened to mimic the peaks that arise from model crystals of a size similar to most cellulosic samples (a few nanometers), it appears that much of the intensity formerly attributed to ‘‘background’’ or ‘‘amorphous scatter’’ is just the overlapped intensity from adjacent crystalline peaks (French 2014). The interpretation that the intensity between peaks results from peak overlap, particularly in the region that Segal attributed to only amorphous intensity, casts doubt on the Segal method as a ‘‘crystallinity’’ determination (French and Santiago Cintrón 2013). It also disqualifies a fourth method, ‘‘amorphous subtraction’’ (Thygesen et al. 2005). The Rietveld method uses the x-, y-, and zcoordinates of the atoms in the crystal structure unit cell such as from Nishiyama et al. (2002) to calculate a diffraction pattern for an ideal crystalline powder. Experimental patterns from cellulose are never ideal, so Rietveld analyses can compensate for the varied unit cell dimensions, inevitable preferred orientation, A. D. French (&) New Orleans, USA e-mail: cellulose.editor@gmail.com
170 citations
TL;DR: In this article, a review describes the recent advances in the production and application of cellulose nanomaterials (CNMs) and their applications in various fields such as medical, sensors, in wastewater treatment, paper and board/packaging industry.
Abstract: This review describes the recent advances in the production and application of cellulose nanomaterials. Cellulose nanomaterials (CNMs), especially cellulose nanocrystals and cellulose nanofibers, can be produced using different preparation processes resulting in materials with unique structures and physicochemical properties that are exploited in different fields such as, biomedical, sensors, in wastewater treatment, paper and board/packaging industry. These materials possess attractive properties such as large surface area, high tensile strength and stiffness, surface tailor-ability via hydroxyl groups and are renewable. This has been a driving force to produce these materials in industrial scale with several companies producing CNMs at tons-per-day scale. The recent developments in their production rate and their applications in various fields such as medical sector, environmental protection, energy harvesting/storage are comprehensively discussed in this review. We emphasize on the current trends and future remarks based on the production and applications of cellulose nanomaterials.
134 citations
TL;DR: In this paper, the authors performed a comprehensive literature evaluation of the biomass sources used to produce cellulose nanofibers and found that 57% were derived from wood-based biomass and 30% from non-wood biomass, with 100 unique biomass sources identified.
Abstract: The rise of biomass-derived nanocellulose addresses the sustainability criteria now demanded of new materials, which have been widely overlooked in the plastics era—renewability, abundance, biodegradability, and recyclability. Cellulose nanofibers have conventionally been extracted from wood products, supported by an established forestry infrastructure, but the drive for biomass sustainability has encouraged researchers to explore non-wood sources over the past 15 years. Non-wood sources, including agricultural residues and industrial wastes, offer an attractive alternative due to their abundance, fast generation, and low starting value. Moreover, agricultural residues can improve the sustainability of cellulose nanofiber processing from multiple angles. The biochemical composition of the typical agricultural residue, which is lower in lignin and higher in hemicellulose than wood stems, improves the fibrillation efficiency of cellulose bundles into nano-scale fibers. In addition, agricultural residues yield high biomass volume from short growth cycles with improved land utilisation, whilst offsetting environmental issues associated with their current uses. In this work, we performed a comprehensive literature evaluation of the biomass sources used to produce cellulose nanofibers. Of the 3358 cellulose nanofiber publications from 2004 to 2018 with an identifiable source material, 57% were derived from wood-based biomass and 30% from non-wood biomass, with 100 unique biomass sources identified. Furthermore, the top research fields associated with non-wood publications included general characterisation (36%), plastic nanocomposites (19%), bionanocomposites (9%), biomedical products (8%), and electronic devices (6%). As social, political and economic drivers reinforce sustainability as a key focus in nanocellulose production, this bibliometric resource provides a timely snapshot of the sustainability trends in cellulose nanofiber research.
119 citations
TL;DR: In this paper, the authors provide an overview of textile based sensors, sensor substrates, and substrate pre-processing including surface modification of the base substrates and different factors affecting the durability and cleaning of conductive textiles.
Abstract: Textile based sensors, an emerging class of wearable devices, are a potential platform for next generation, functionality and amenability for the human body incorporating sensing and control. The main purpose of this review is to provide an overview of textile based sensors, sensor substrates, and substrate pre-processing including surface modification of the base substrates. This review also summarizes various conducting polymers and inks, production methods of developing robust conductive fibres or textiles, and different factors affecting the durability and cleaning of conductive textiles. This manuscript also critically examines properties relating to acceptability and performance of textile based sensors which are subjected to wear and care during repeated use e.g. care, maintenance, and durability. This aspect (wear and care) of performance is often ignored during development. Wear and care effects on performance need to be understood and solutions found for extending the life cycle and performance of textile based sensors.
104 citations
TL;DR: In this paper, Ag2WO4@MIL-125-NH2@cotton and Ag3VO4@Mil-125 NH2@Cotton were applied as photocatalysts in the degradation of Methylene Blue (MB) and Rhodamine B (RhB) dyes in the visible light.
Abstract: Photocatalysts are highly applicable in treatment of the water pollution. However, most of the applied photocatalysts suffer from the inapplicability and non-recyclability which limited their application. Herein, applicable and recyclable effective photocatalyst composites of Ag2WO4@MIL-125-NH2@cotton and Ag3VO4@MIL-125-NH2@cotton successfully prepared by direct synthesis of MIL-125-NH2 and Ag2WO4 or Ag3VO4 within the cotton fabric as supported template, sequentially. Agglomerated rock structure of Ag2WO4@MIL-125-NH2 and smaller particles of Ag3VO4@MIL-125-NH2 formed onto the cotton. The prepared composites applied as photocatalysts in the degradation of Methylene Blue (MB) and Rhodamine B (RhB) dyes in the visible light. The highest photodegradtion of dyes observed for Ag2WO4@MIL-125-NH2@cotton and Ag3VO4@MIL-125-NH2@cotton composites because of their low optical band gaps (2.36 eV and 1.87 eV) and their quenching in luminescent spectrum which helped in the ease transfer of photoexcited electrons. The rate constant (k2) for the photodegradation of MB (RhB) dye reduced significantly from 1.78 × 10–3 (2.8 × 10–3) L/mg min to 0.43 × 10–3 (1.04 × 10–3) L/mg min and 0.29 × 10–3 (0.79 × 10–3) L/mg min, when Ag2WO4 and Ag3VO4 incorporated in MIL-125-NH2@cotton composite, respectively. After 4 recycling process, the photodegradation activity of the applied composites diminished from 86–92% (68–80%) to 58–65% (47–54%). The obtained results declared the topmost photocatalytic activity in daylight of the recyclable prepared tri-component composites, reflecting their promising potentials in environmental applications.
96 citations
TL;DR: In this article, post-harvest tomato plant residue (TPR) was proposed as a viable and sustainable source for the extraction of cellulose derivatives, namely cellulose microfibers (CMF) and cellulose nanocrystals (CNC).
Abstract: With the aim of identifying new sources for cellulose manufacturing, post-harvest tomato plant residue (TPR) was proposed in this study as a viable and sustainable source for the extraction of cellulose derivatives, namely cellulose microfibers (CMF) and cellulose nanocrystals (CNC). Pure CMF with an average diameter of 20 µm were successfully produced by subjecting the raw TPR to chemical treatments and then characterized in terms of their morphology and physico-chemical characteristics. By subjecting CMF to sulfuric, phosphoric and citric/hydrochloric acid hydrolysis, sulfated CNC (S-CNC), phosphorylated CNC (P-CNC) and carboxylated CNC (C-CNC) have been successfully produced. This was done to produce CNC with different characteristics and surface functionalities depending on the inserted functional groups during the acid hydrolysis process. By using several characterization techniques, it was found that all the extracted CNC characterized by cellulose I structure, with a crystallinity index of 81–89, 81 and 78%, an aspect ratio of 40–49, 98 and 67 and zeta potential of − 27.8 to − 37.3, − 36.9 and − 22.3 mV for S-CNC, P-CNC and C-CNC, respectively. The determined thermal stability of all extracted CNC is relatively higher than that generally obtained for S-CNC from other sources, which suffer from limited thermal stability. The produced CNC with different surface functionalities formed stable colloidal suspensions in polar solvents such as water and dimethyl sulfoxide. The production of CMF and CNC from this underutilized waste has the potential to add value to the post-harvest tomato plant, which is produced annually as waste in vast quantities throughout the world, in addition to significantly reducing the volume of cumulative waste in the environment.
93 citations
TL;DR: In this article, nanoscale lignin with high content of hydroxyl groups and small particle size in prehydrolysate was isolated and used as a green reinforcement ingredient for fabrication of cellulose nanofibril (CNF) films with excellent mechanical properties, as well as UV protection and antibacterial capabilities.
Abstract: Cellulose is lack of UV-blocking and antibacterial properties, which have limited its application. In this work, the nanoscale lignin with high content of hydroxyl groups and small particle size in prehydrolysate was isolated and used as a green reinforcement ingredient for fabrication of cellulose nanofibril (CNF) films with excellent mechanical properties, as well as UV protection and antibacterial capabilities. Cryogenic transmission electron microscopy (Cryo-TEM) and nuclear magnetic resonance analyses showed that the resulting lignin was in the form of nanoparticles (6–12 nm) with high phenolic hydroxyl contents (4.9 mmol/g). The optimum lignin inclusion rate of 5% allowed it to reinforce CNF composite film, increasing its tensile strength from 108.5 to 143.3 MPa. In addition, the film exhibited excellent UV protection capabilities. It blocked 91.5% of UV-A and 99.9% of UV-B light. Finally, the resulting lignin-based CNF films exhibited antibacterial activities against both Escherichia coli and Streptococcus hemolyticus. This work demonstrates the utility of nanoscale lignin from prehydrolysate can be used to produce cellulose-based composite films with valuable properties.
92 citations
TL;DR: In this paper, the present state and recent progress in the area of lignin-containing cellulose nanofibrils (LCNFs), an emerging family of green cellulose nano-materials, is discussed.
Abstract: This review outlines the present state and recent progress in the area of lignin-containing cellulose nanofibrils (LCNFs), an emerging family of green cellulose nanomaterials. Different types of LCNF raw materials are described, with main focus on wood-based raw materials, and the properties of the resulting LCNFs are compared. Common problems faced in industrial utilization of CNFs are discussed in the light of potential improvements from LCNFs, covering areas such as chemical and energy consumption, dewatering and redispersibility. Out of the potential applications, barrier films, emulsions and nanocomposites are considered.
86 citations
TL;DR: The properties and applications of BC, a promising biomaterial that has potential application in electronics, cosmetics, medicine and food and its related products, are discussed.
Abstract: Bacterial cellulose (BC) is a promising biomaterial due to its specific and excellent properties such as high cellulose purity, mechanical strength, high crystallinity and biodegradability. BC has potential application in electronics, cosmetics, medicine and food and its related products due to its properties. Various chemical compounds have been added to the BC production process to analyse the effect on the BC yield and enhance BC’s properties. In this review, we discuss in-situ and ex-situ modifications and biotechnological approach as alternative optimisation methods in BC production. Given that BC has excellent structural characteristics, which lead to better physical and mechanical properties compared with plant cellulose, the properties and applications of BC are also discussed in this paper.
86 citations
TL;DR: In this paper, a new peak deconvolution method was proposed to analyze cellulose X-ray diffraction data with the amorphous Fourier model function in conjunction with standard Voigt functions representing the crystalline peaks.
Abstract: This paper addresses two fundamental issues in the peak deconvolution method of cellulose XRD data analysis: there is no standard model for amorphous cellulose and common peak functions such as Gauss, Lorentz and Voigt functions do not fit the amorphous profile well. It first examines the effects of ball milling on three types of cellulose and results show that ball milling transforms all samples into a highly amorphous phase exhibiting nearly identical powder X-ray diffraction (XRD) profiles. It is hypothesized that short range order within a glucose unit and between adjacent units survives ball milling and generates the characteristic amorphous XRD profiles. This agrees well with cellulose I d-spacing measurements and oligosaccharide XRD analysis. The amorphous XRD profile is modeled using a Fourier series equation where the coefficients are determined using the nonlinear least squares method. A new peak deconvolution method then is proposed to analyze cellulose XRD data with the amorphous Fourier model function in conjunction with standard Voigt functions representing the crystalline peaks. The impact of background subtraction method has also been assessed. Analysis of several cellulose samples was then performed and compared to the conventional peak deconvolution methods with common peak fitting functions and background subtraction approach. Results suggest that prior peak deconvolution methods overestimate cellulose crystallinity.
85 citations
TL;DR: In this article, the synthesis and modification of kombucha-derived bacterial cellulose in order to produce textiles of desired physicochemical and mechanical properties was presented, which can be used to manufacture various articles of clothing using commonly available sewing techniques.
Abstract: In this paper, we present a novel, ecologically friendly technology for the synthesis and modification of kombucha-derived bacterial cellulose in order to produce textiles of desired physicochemical and mechanical properties. The procedure of manufacturing cellulose in the form of a stable hydrogel bacterial cellulose (HGBC) ensures the desired properties for the application of such a material, e.g., in the textile industry. Bacterial cellulose was obtained from a yeast/bacteria kombucha culture (a symbiotic consortium also known as “tea fungus” or SCOBY) that is easy and cheap to breed. The process of bacterial cellulose manufacturing and modification was optimized in order to obtain a maximum recovery of raw materials, minimal energy consumption and ensure the use of only natural and renewable resources. The obtained materials were characterized in terms of their wettability, mechanical properties, and flame resistance. Moreover, the morphology and composition of the materials were determined by using scanning electron microscopy and infrared spectroscopy, respectively. Additionally, it was proven that the HGBC materials might be used to manufacture various articles of clothing using commonly available sewing techniques, which are not adequate for non-modified cellulose-based materials. Finally, the synthesized fabrics were used as wristbands and parts of T-shirts and tested on volunteers to determine a skin-to-skin contact behaviour of the prepared fabrics. The reported results allow for confirming that the HGBC fabric may be used as a new textile and the proposed synthesis method is in accordance with the “green chemistry.”
TL;DR: In this article, the morphological, spectroscopic, and stability properties of the as-prepared rod-shaped CNCs were characterized using zeta potential, X-ray diffraction, transmission electron microscopy, scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric techniques.
Abstract: Cellulose nanocrystals (CNCs) have been widely used as renewable materials and tough nano-composites due to its excellent properties. Currently, the preparation methods of CNCs require substantial energy and time consumption and the use of toxic chemicals. Herein, cotton and other biomass feedstocks were treated with deep eutectic solvents (DESs) and subsequent high-pressure homogenization (HPH), which was a simple preparation procedure for CNCs. The morphological, spectroscopic, and stability properties of the as-prepared rod-shaped CNCs were characterized using zeta potential, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, fourier transform infrared spectroscopy and thermogravimetric techniques. CNCs with a diameter range of 50–100 nm and a length range of 500–800 nm were successfully assembled. The resulting CNC suspension was stable even after one month of storage. The solvent could be recycled successfully and reused for at least three additional pretreatment cycles while maintaining its pretreatment capability. The use of a DES as both the catalyst and solvent introduces a green chemical process that does not produce any hazardous waste and is an economical process because of the high recyclability (> 85%). The molecular structure changes of cellulose after HPH and DES treatment were also discussed. This is the first report on the recycling and reuse of a DES after preparing CNCs.
TL;DR: In this paper, the authors summarized the recent work on the extraction, modification, and food-related applications of CNCs and discussed the potential applications in food packaging, food thickener, emulsion stabilization, quality sensor, and active compound immobilization.
Abstract: Cellulose nanocrystals (CNCs) with prominent mechanical properties are well known as the natural reinforcing elements in composites and have received considerable interest over the past decades. Numerous original resources and extraction methods were applied to obtaining CNCs, and the surface properties of CNCs were modified to improve the compatibility with polymeric matrices. Despite these different raw materials and treatments, various novel applications of CNCs have been developed in recent years. Among them, the food-related applications of CNCs have attracted more and more attention because of their renewability, outstanding mechanical properties, unique nanoscale structure, biocompatibility, and easy surface modifications. This review summarized the recent work on the extraction, modification, and food-related applications of CNCs. Traditional raw materials, such as cotton, wood, and tunicate, were still widely used, while there is a new trend to obtain CNCs from waste biomass. Different pretreatments, extraction processes, and surface modifications were compared and discussed. Moreover, the potential applications of CNCs in food packaging, food thickener, emulsion stabilization, quality sensor, and active compound immobilization were presented. Finally, concerns about safety and sustainability have been addressed.
TL;DR: In this paper, the authors reported successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated in Sweden.
Abstract: We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated ...
TL;DR: In this paper, an optical cellulose fiber for water sensoring was prepared by using a sequential preparation strategy, in which the core of the fiber was prepared from dissolved cellulose, in [EMIM]OAc, which was dry-wet spun into water.
Abstract: In this study an optical cellulose fiber for water sensoring was prepared by using a sequential preparation strategy. The core of the fiber was prepared from dissolved cellulose, in [EMIM]OAc, which was dry–wet spun into water. The cladding layer on the cellulose core was produced by coating a layer of cellulose acetate, dissolved in acetone, using a filament coater. The chemical and optical properties of both regenerated cellulose and cellulose acetate were studied from cast films using ultraviolet–visible and Fourier-transform infrared spectroscopy measurements. Regenerated cellulose film was observed to absorb UV light, passing the visible light wavelengths. Cellulose acetate film was observed to pass the whole light wavelength range. The mechanical strength and topography of the prepared optical cellulose fiber were investigated through tensile testing and SEM imaging. The mechanical performance of the fiber was similar to previously reported values in the literature (tensile strength of 120 MPa). The prepared optical fiber guided light in the range of 500–1400 nm. The attenuation constant of the cellulose fiber was observed to be 6.3 dB/cm at 1300 nm. The use of prepared optical cellulose fiber in a water sensor application was demonstrated. When the fiber was placed in water, a clear attenuation in the light intensity was observed. The studied optical fiber could be used in sensor applications, in which easy modifiability and high thermal resistance are beneficial characteristics.
Coaxial cellulose acetate-regenerated cellulose fiber for transporting light in sensor optical fiber sensor applications.
TL;DR: In this paper, a graft-copolymerization technique using the crosslinked hydrogel of Carrageenan (KC) and AQSOA-Z05 zeolite was used to synthesize a ZHC for water remediation applications for methylene blue (MB) dye adsorption.
Abstract: This work reports the preparation of zeolite hydrogel composite (ZHC) based on κ-carrageenan (KC) and AQSOA-Z05 zeolite and its potential use in water remediation applications for methylene blue (MB) dye adsorption. The ZHC was synthesized via the graft-copolymerization technique using the crosslinked hydrogel of KC as polymer matrix. Effects of incorporating zeolite particles within the hydrogel matrix on the properties were studied using different characterization techniques such as TEM, X-ray diffraction, SEM and FTIR. The hydrogel composite with 8% loading of zeolite exhibited maximum swelling capacity (3.481%) among the synthesized ZHCs. For MB removal, ZHC adsorbed 99% dye with 0.4 g L−1 adsorbent dose in the neutral pH solution. Furthermore, the adsorption of MB onto ZHC followed pseudo-second-order and Langmuir isotherm models. The ZHC exhibited maximum adsorption capacities of 661.91 at 298.18 K, 674.05 at 308.15 K and 682.67 mgdye gads−1 at 318.15 K. Dye diffusion mechanism partially followed both liquid film and intra-particle diffusion mechanisms. Results obtained from thermodynamics experiments suggested the endothermic nature of the MB adsorption on ZHC. MB was selectively adsorbed from the binary dye mixtures having MB and methyl orange in different concentration ratio. In addition, the ZHC showed excellent adsorption behavior for six continuous adsorption–desorption cycles. Therefore, the synthesized ZHC has all the properties to be used as a potential adsorbent for the treatment of cationic dyes contaminated wastewater.
TL;DR: In this paper, a simple and green approach to prepare biocompatible adsorbents with two environmentally friendly raw materials, cellulose nanocrystals (CNCs) and mussel-inspired polydopamine (PDA), was presented.
Abstract: It remains a great challenge to develop environmentally friendly adsorbents with large adsorption capacity, fast adsorption speed, and high regenerability from eco-friendly and cheap biomaterials. Herein, we present a simple and green approach to prepare biocompatible adsorbents with two environmentally friendly raw materials, cellulose nanocrystals (CNCs) and mussel-inspired polydopamine (PDA). The resultant CNC@PDA nanocomposites show a ditinct core–shell structure with a very thin PDA coating, providing a high specific surface area of 107.2 m2/g for adsorption sites. The CNC@PDA nanocomposites have an exceptionally high adsorption capacity of up to 2066.72 mg/g for MB and can rapidly sequester MB from water within 5 min at high initial MB concentration of 500 mg/L. Moreover, CNC@PDA nanocomposites can be regenerated by a simple method and maintain high adsorption capacity for MB even after multiple adsorption–desorption cycles. The work provides promising results for the developed CNC@PDA materials as economical adsorbent materials for effective and efficient dye decontamination of the wastewater.
TL;DR: A survey of the literature reveals that nanocellulose materials have a proven track record as viable alternatives as adsorbents as discussed by the authors, and this review describes the methodologies under current use for such designs and gives a systematic overview of these technologies.
Abstract: Efficient separation and removal is necessary in applications ranging from environmental remediation to the food sector. A well-designed adsorption system should meet the demands for high efficiency in a cost and time effective manner. In wastewater treatment, the ideal chemical feedstock used to synthesize the adsorbents should themselves been environmentally friendly (i.e. non-toxic) to avoid subsequent environmental issues. Nanocellulose, made of the most abundant organic biopolymer on earth, fulfills many criteria to fit the profile of a highly safe, but efficient adsorbent. A survey of the literature reveals that nanocellulose materials have a proven track record as viable alternatives as adsorbents. To summarize these recent advances, this review describes the methodologies under current use for such designs and gives a systematic overview of these technologies to promote a more focused research in the future for nanocellulose based adsorbent materials.
TL;DR: Results supported potential of this non-toxic, biofriendly and appropriately tailored polysaccharide based hydrogel to be used as drug delivery carrier for controlled and site-specific drug release.
Abstract: The work was intended to develop a novel acrylic acid grafted hydrogel by chemical crosslinking of xanthan gum and starch under microwave irradiation. The swelling capacity of hydrogel was found to be dependent upon pH. The maximum swelling capacity of hydrogel was recorded as 32.21 g/g under the optimized conditions. The swelling capacity of hydrogel was quite higher than most of the hydrogels containing xanthan gum mentioned in the literature. Various characterization techniques including FTIR, SEM, TGA and XRD confirmed successful synthesis of hydrogel with porous morphology and better thermal stability. Synthesized hydrogel was employed as an oral drug delivery vehicle. Releasing behavior of the hydrogels for the drugs aspirin and paracetamol was studied under specific physiological conditions. The drug release was significantly higher at pH 7.4 in comparison to acidic and neutral media. Synthesized hydrogel was found to be suitable for colon-specific drug delivery. Both aspirin and paracetamol followed non-Fickian diffusion mechanism at higher pH and Fickian mechanism at lower pH. Release profiles of both the drugs were best fitted in the first order model. Hydrogel was found to be non-cytotoxic to human fibroblast cells and biocompatible, with a low hemolytic ratio. Consequently results supported potential of this non-toxic, biofriendly and appropriately tailored polysaccharide based hydrogel to be used as drug delivery carrier for controlled and site-specific drug release.
TL;DR: In this paper, the thermal conductivities of the CNF-based composites are analyzed with respect to the heat transfer mechanism, thermal conductivity of the polymer, the loading of the filler, the size and morphology of a filler, and the type of filler.
Abstract: The natural world abounds in lignocellulosic biomass, which is an environmentally friendly renewable resource. Cellulose nanofibrils (CNFs) made from biomass have the advantages of high optical transparency, light weight, good mechanical properties, high specific surface area and biodegradability. Increasing applications of CNFs have been identified in emerging high-tech fields, such as flexible electronics and clean energy. A variety of thermal management materials have been discussed in flexible electronic products. This paper reviews the merits of CNFs compared to other polymers in flexible electronic products and emphasizes the application status of CNF-based thermal management materials in flexible electronic products. The thermal conductivities of the CNF-based composites are analyzed with respect to the heat transfer mechanism, the thermal conductivity of the polymer, the loading of the filler, the size and morphology of the filler, the type of filler, and the surface treatment of the filler. Current challenges and future research opportunities are also discussed, offering a reasonable and scientific route for the structural design of future flexible thermal management materials that will promote the development of the flexible electronics industry.
TL;DR: In this paper, a superhydrophobic, flame-retardant and conductive cotton fabrics were fabricated by sequential assembly of poly(ethylenimine), ammonium polyphosphate and carbon nanotubes, followed by post-treatment with poly(dimethylsiloxane).
Abstract: Functional textiles are ideal substrates for wearable electronics. Herein, superhydrophobic, flame-retardant and conductive cotton fabrics were fabricated by sequential assembly of poly(ethylenimine), ammonium polyphosphate and carbon nanotubes, followed by post-treatment with poly(dimethylsiloxane). The resulting fabrics possessed excellent superhydrophobic stability toward acid, alkali, organic solvent, UV irradiation, abrasion and long-time laundering. Meanwhile, when suffering to fire, the coated fabric could generate an efficient char layer and extinguish the fire to protect the cotton fiber from forming flame. Furthermore, this conductive cotton fabric exhibited stable sensing ability in contact with water droplets, showing wide potential application in wearable electronics as multifunctional smart textiles.
TL;DR: In this paper, a novel cyclic-shaped copolymer containing silicon and phosphorus, poly (tetramethylcyclosiloxyl spirocyclic pentaerythritol diphosphonate) (PCTSi) was successfully synthesized and characterized by Fourier transform infrared spectra (FT-IR), 1H and 13C nuclear magnetic resonance (1H NMR and 13c NMR) for the preparation of flame retardant and hydrophobic cotton fabrics.
Abstract: A novel cyclic-shaped copolymer containing silicon and phosphorus, poly (tetramethylcyclosiloxyl spirocyclic pentaerythritol diphosphonate) (PCTSi) was successfully synthesized and characterized by Fourier transform infrared spectra (FT-IR), 1H and 13C nuclear magnetic resonance (1H NMR and 13C NMR) for the preparation of flame retardant and hydrophobic cotton fabrics. The surface morphology of treated cotton fabrics was characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The thermal degradation and combustion properties of cotton fabrics before and after treatment were investigated by thermogravimetric (TG) analysis, limiting oxygen index (LOI) test, vertical burning test and cone calorimetry test. After treated with PCTSi, the LOI value of coton fabrics increased to 29.5%, which was significantly higher than untreated cotton fabrics and the LOI value remained at above of 26.0% after 20 washing times. In the vertical burning test, the PCTSi treated cotton fabrics showed no afterflame and afterglow with a minimum char length of 8.5 cm. Thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) results indicated that flame-retardant cotton fabrics released nonflammable gases and less flammable gases than the untreated cotton fabrics. X-ray diffraction analysis demonstrated that the crystal structures of the PCTSi-treated cotton were almost unaffected. According to the results of TG-FTIR, SEM, EDS, and analyses of char residues, the cyclic-shaped copolymer can significantly improve flame retardant performance of cotton fabric by promoting the generation of char layer and the release of noncombustible volatiles. The treated cotton fabrics showed excellent hydrophobic properties, which reached a contact angle (CA) of 150° compared with cotton fabrics without treatment. In addition, 119.18° of CA and 26.0% of LOI value can be maintained after 20 washing times.
TL;DR: In this paper, a review of cellulose nanomaterials is presented to identify the toxicological effects that are elicited by nanocelluloses produced through a top-down approach from vegetal biomass.
Abstract: The need for reaching environmental sustainability encourages research on new cellulose-based materials for a broad range of applications across many sectors of industry. Cellulosic nanomaterials obtained from different sources and with different functionalization are being developed with the purpose of its use in many applications, in pure and composite forms, from consumer products to pharmaceutics and healthcare products. Based on previous knowledge about the possible adverse health effects of other nanomaterials with high aspect ratio and biopersistency in body fluids, e.g., carbon nanotubes, it is expected that the nanometric size of nanocellulose will increase its toxicity as compared to that of bulk cellulose. Several toxicological studies have been performed, in vitro or in vivo, with the aim of predicting the health effects caused by exposure to nanocellulose. Ultimately, their goal is to reduce the risk to humans associated with unintentional environmental or occupational exposure, and the design of safe nanocellulose materials to be used, e.g., as carriers for drug delivery or other biomedical applications, as in wound dressing materials. This review intends to identify the toxicological effects that are elicited by nanocelluloses produced through a top-down approach from vegetal biomass, namely, cellulose nanocrystals and nanofibrils, and relate them with the physicochemical characteristics of nanocellulose. For this purpose, the article provides: (i) a brief review of the types and applications of cellulose nanomaterials; (ii) a comprehensive review of the literature reporting their biological impact, alongside to their specific physicochemical characteristics, in order to draw conclusions about their effects on human health.
TL;DR: An eco-friendly, low-cost, and highly efficient adsorbent based on biomass material, cellulose matrix-supported metal-organic-framework (MOF) hybrid aerogel (ZIF-67@CA), was designed and prepared by in situ growth of ZIF67 nanoparticles on pre-synthesized chemically crosslinked cellulose aerogels.
Abstract: An eco-friendly, low-cost, and highly efficient adsorbent based on biomass material, cellulose matrix-supported metal-organic-framework (MOF) hybrid aerogel (ZIF-67@CA), was designed and prepared by in situ growth of ZIF-67 nanoparticles on pre-synthesized chemically crosslinked cellulose aerogel. The chemical structure and surface morphology of as-prepared ZIF-67@CA were characterized by various methods. Analysis results confirmed the successful formation of a densely coated layer of ZIF-67 on the surface of the cellulosic aerogel. Owing to its large specific surface area and electrostatic attraction of ZIF-67 with methyl orange (MO), ZIF-67@CA exhibited high adsorption capacity of up to 617 mg g−1 for MO, which was more than four times higher than that of the pristine cellulose aerogel. Additionally, ZIF-67@CA could selectively separate anionic dye from the dye mixture and maintain 90% adsorptivity even after five cycles of repeated usage. Hence, this work provided a feasible solution and scalable platform for the functional design and rational manufacture of MOF-based cellulose aerogel. Moreover, the versatility of its structural design makes it a promising adsorbent material for wide application range of wastewater treatment.
TL;DR: In this article, the effect of using the effective enzymes produced from Rhizopus microspores AH3 which is grown on watermelon peel waste (WPW) extract, as a bio-deinking method in the deinking of MOWP, which is difficult to recycle because of their ink type and printing process.
Abstract: Mixed office waste paper (MOWP) is a low cost, high quality and easily collected fiber source for the papermaking industry. Unfortunately, limits in the application of traditional deinking are related to the negative environmental impacts of using chemicals during the deinking process. Hence, enzymatic deinking has received growing attention in the last decade. This study investigates the effect of using the effective enzymes produced from Rhizopus microspores AH3 which is grown on watermelon peel waste (WPW) extract, as a bio-deinking method in the deinking of MOWP, which is difficult to recycle because of their ink type and printing process. The methodology involves preparation of samples, impregnation with water, enzymatic treatment, washing, papermaking, evaluation of the produced paper sheets. The evaluation includes determination of the optical and mechanical properties as well as topographic investigation via scanning electron microscope of produced paper sheets. The results showed that there is an improvement in both optical and mechanical properties of all paper sheets produced in this study. The best enhancement was for medium B30 which was extracted by boiling of WPW for 30 min. This treatment gave high enhancement because of the effect of the produced enzymes from Rhizopus microspores AH3, where cellulase, xylanase, lignin peroxidase, poly phenol oxidase and laccase were 1.62, 1.49, 1.38, 1.2 and 1.5 U/ml, respectively. Moreover, the tensile strain (maximum load) increased by about 77% as well as the brightness percentage achieved about 86.78% and the deinking ability was increased approximately 16%.
TL;DR: In this paper, a new silicon-phosphorus-nitrogen flame retardant, di-(trimethoxysilylpropyl) spirocyclic pentaerythritol bisphosphorate (SPDP-PTMS), was synthesized and the SPDP treated cotton fabrics were prepared using sol-gel technology.
Abstract: A new silicon–phosphorus–nitrogen flame retardant, di-(trimethoxysilylpropyl) spirocyclic pentaerythritol bisphosphorate (SPDP-PTMS) was synthesized and the SPDP-PTMS treated cotton fabrics were prepared using sol–gel technology. The chemical structure of SPDP-PTMS was characterized by FT-IR and 1H NMR. The surface morphologies and elemental changes of SPDP-PTMS treated cotton fabrics and char residues were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer. After treating with 500 g/L SPDP-PTMS, the LOI value reached 29.5% and maintained 26.2% after 20 washing times. The char length of cotton fabrics treated with 500 g/L SPDP-PTMS was 8.8 cm with no afterflame and afterglow in the vertical burning test. The thermal stability of SPDP-PTMS treated cotton fabrics was improved and measured by thermogravimetric (TG) analysis. In the cone calorimetry test, the peak heat release rate and total heat release decreased from 232.1 to 179.4 kW/m2 and from 6.5 to 4.5 MJ/m2, and the char residue reached 23.5%. Thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) results indicated that SPDP-PTMS treated cotton fabrics released nonflammable gases and less flammable gases than the untreated cotton fabrics. The analysis of the data proved that SPDP-PTMS might have a flame retardant effect by releasing non-flammable gases and forming a stable char layer.
TL;DR: In this article, the authors investigated the adsorption characteristic of magnetized Tectona grandis sawdust for methylene blue from aqueous media, and the removal efficiency was found to be 90.8% under the optimized adaption conditions.
Abstract: In the submitted research work, adsorption characteristic of magnetized Tectona grandis sawdust for methylene blue from aqueous media was explored. The prepared adsorbent was characterized by SEM/EDXS, TEM, BET, XRD, FTIR, TGA-DTG/DTA, VSM, and point of zero charge. To investigate the adsorption capacity and mechanisms prevailing for the adsorption of methylene blue, batch adsorption studies were performed by changing adsorbate/adsorbent contact time, pH, initial dye concentration, and temperature. The removal efficiency was found to be 90.8% under the optimized adsorption conditions. The optimal process parameters were 1 g/L of magnetized adsorbent, 60 min contact time, pH 8, and temperature of 30 °C for 100 mg/L MB solution. The laboratory generated adsorption data was best conformed by pseudo-second-order kinetics and Langmuir adsorption isotherm models. The maximum monolayer adsorption capacity was determined to be 172.41 mg/g. The adsorption process was established to be thermodynamically feasible and accompanying with the absorption of heat and escalation of entropy. Regeneration study revealed that magnetized Tectona grandis sawdust could be reused efficaciously up to four repeated adsorption–desorption cycles using HCl as the best desorbing agent. The magnetized Tectona grandis sawdust has been proved to be novel, efficient, and cost-effective adsorbent. The combined advantages of easy preparation, good affinity towards dyes, excellent separability, reusability, and cost-effectiveness of magnetized Tectona grandis sawdust make it a novel adsorbent.
TL;DR: In this paper, a superhydrophobic cotton fabric was fabricated through the combination of micro-nano-binary structure of polydopamine (PDA) and grafting of octadecylamine (ODA).
Abstract: Oily wastewater seriously pollutes the environment, and is difficult to separate. In this work, superhydrophobic cotton fabrics were fabricated through the combination of micro–nano-binary structure of polydopamine (PDA) and grafting of octadecylamine (ODA). Herein, fluorine-free compounds were used. The PDA binary structure was rapidly deposited on cotton fabric under the catalysis of metal salts and oxidants. Then, the ODA was grafted onto the cotton fabric through Schiff base reaction with o-quinone formed by oxidation of the catechol structure of PDA, which covered the surface of PDA coated cotton fabric. The superhydrophobic cotton fabric with contact angle up to 163.7° and scroll angle around 9° was obtained. Due to the excellent adhesion of polydopamine, the superhydrophobic cotton fabric demonstrated great stability and durability under a variety of harsh environmental conditions. After coating the polyurethane (PU) sponge with the prepared superhydrophobic cotton fabric, an oil absorbing bag was made and it showed good oil–water separation even after being reused 20 times, and the prepared cotton fabric also had excellent self-cleaning performance. This facile strategy of preparation of superhydrophobic materials for continuous oil–water separation is quick, efficient and environmentally friendly, which has great prospect for application in removal of marine oil spills.
TL;DR: In this paper, a facile method on fabricating aerogels with hierarchical porous structures was created by freeze-drying the cellulose nanofibril (CNF)/methyltrimethoxysilan (MTMS)/fumed silica (FS) suspension.
Abstract: Herein, a facile method on fabricating aerogels with hierarchical porous structures was created by freeze-drying the cellulose nanofibril (CNF)/methyltrimethoxysilan (MTMS)/fumed silica (FS) suspension. FS was introduced for its porous structure, which could improve the thermal insulation performance of freeze-dried aerogels. The as-prepared aerogels were hydrophobic with improved mechanical properties (elastic recovery rate was up to 99.7%) and reduced thermal conductivity (0.027 Wm−1 K−1 at 25 °C). Most importantly, the addition of FS was proved to improve the thermal insulation stability of cellulose aerogels efficiently in different values of relative humidity (RH) and temperatures. The thermal conductivity of pure CNF aerogel conditioned at 25 °C and 95% RH was 196% higher than that of the fully-dried one, while the increase was 56% for the composite aerogel. Besides, at 30% RH, the thermal conductivity increased by 24% for the pure CNF aerogel when tested from 20 to 60 °C while only a 2% increase for the composite aerogel. Moreover, when tert-butanol was used as the solvent to optimize the distribution of the pores of freeze-dried aerogels, their thermal insulation performance was further improved. Our work provides easily available CNF/MTMS/FS ternary aerogels, which are stable in thermal conductivity in the changing environment.
TL;DR: While the stability and mechanical properties of collagen hydrogel was enhanced by adding CNF, the MTT assay revealed the same cell viability for collagen/CNF scaffold as collagen, and the live-dead assay demonstrated excellent capability of CNF nanocomposite for cell 3D culturing.
Abstract: Collagen hydrogel applications in tissue engineering are limited due to its weak physical and mechanical properties, e.g. loss of water, destruction in the biological medium, weak mechanical properties, and handling difficulty. To improve the physical and mechanical properties of collagen hydrogel, cellulose nanofibers (CNF) were introduced to the collagen hydrogel. Up to 8% CNF, by total dry weight, was added to cold collagen acidic solution and the solution underwent gel formation by increasing pH and temperature to 7.4 and 37 °C, respectively. The gelation time was decreased when CNF was added to the collagen solution. The scanning electron microscopy images of collagen/CNF nanocomposites illustrated porous morphology with larger pore and denser nanofibrous structure than pure collagen. More water retention ability of collagen/CNF hydrogels along with lower hydrolytic degradation rate indicated higher stability of CNF composite hydrogels than pure collagen hydrogel. Mechanical testing demonstrated enhancement in both compression strength and fracture strain when CNF was added to the collagen hydrogel. The presence of free CNF and possible interactions between collagen and CNF was demonstrated by thermogravimetric and Fourier-transform infrared analysis. While the stability and mechanical properties of collagen hydrogel was enhanced by adding CNF, the MTT assay revealed the same cell viability for collagen/CNF scaffold as collagen. Furthermore, the live-dead assay demonstrated excellent capability of CNF nanocomposite for cell 3D culturing.