Mercerized Cellulose Research Articles

Silicified microcrystalline cellulose from renewable banana pseudostem: Physicochemical and functional analysis.

Microcrystalline cellulose (MCC) has been isolated from numerous sources through acid hydrolysis of mercerized cellulose. Due to the fibrous shape, its poor flow ability and lower compactibility, MCC is often co-processed with other excipients to improve its functional properties. Musa MCC was isolated from the pseudostem of Musa balbisiana and silicified with 2 % silicon dioxide (SMCC) through homogenization followed by filtration and oven drying. Both Musa MCC and SMCC were thoroughly characterized through FTIR, SEM- EDS, XRD, and TGA-DTG analysis. Detailed pharmaceutical functional properties including packing and rearrangement, consolidation, compressibility, compactibility and tabletability were also investigated and compared against the standard commercial grade MCC. While the percent crystallinity was reduced by silicification, there was enhanced resistance to thermal degradation. By reducing the internal friction, silicification was able to decrease the cohesiveness and improve the flow property of MCC. From Heckel plot and the yield pressure obtained, silicification reduces the extent of plastic deformation of MCC. However, silicification successfully improved the compactibity, tabletability and manufacturability of the Musa MCC. Results from these analyses show that the pseudostem of M balbisiana is a potential sustainable source of highly functional MCC and the silicification process improved the compactibility and tabletability of the MCC.

Fabrication of cellulose-collagen based biosorbent as eco-friendly scavengers for uranyl ions

The aim of the present research is to fabricate a biosorbent using agricultural waste for removal of uranium from contaminated water i.e. “waste to wealth” approach. Cellulose extracted from wheat straw was mercerized and a novel semi-interpenetrating polymer network (semi-IPN) was fabricated through graft copolymerization of polyvinyl alcohol onto hybrid mercerized cellulose + collagen backbone. Response surface methodology was used for optimization of different reaction parameters as a function of % grafting (195.1 %) was carried out. Semi-IPN was found to possess higher thermal stability. Adsorption results revealed that the optimum parameters for the elimination of uranium using semi-IPN were: adsorbent dose = 0.15 g, pH = 6.0, contact time = 120 min and initial U (VI) concentration = 100 μg/L. The pseudo-second-order kinetic model gave the best description of the adsorption equilibrium data as the calculated qe value is nearest to the experimental qe for the different initial U(VI) concentrations. Adsorption experiments followed Langmuir isotherm with R2 = 0.999. Furthermore, recyclability and reusability studies showed that the adsorption efficiency of semi-IPN was 82 % after 5 cycles indicating the superior recycling execution of fabricated biosorbent. Thus, the fabricated ecofriendly device can be used effectively for the removal of uranium from contaminated wastewater sources.

Oil dispersing and adsorption by carboxymethyl cellulose–oxalate nanofibrils/nanocrystals and their kinetics

AbstractThe aim of our work is the preparation of cellulose nanofibrils or nanocrystals made from cellulose that is recovered from sugarcane bagasse agricultural waste (SC) as a dispersant instead of commercial cellulose for oil spill cleanup. In the current study, carboxymethyl cellulose was prepared by cellulose mercerization, which was then esterified by oxalic acid to create nanocellulose. Incorporation of oxalate into carboxymethyl cellulose (CMC) was verified by 1H‐NMR spectroscopy by the appearance of a new peak at 8.15 ppm for CMC–oxalate. The degree of substitution (DS) of oxalate was 0.17. The synthesized nanocellulose formed particles were roughly the same size and shape as both cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs): measuring 321–480 nm in length and 4–5 nm in width. Emulsions of paraffins made from CMC–oxalate are stable up to 10 months without undergoing precipitation. CMC–oxalate had great thermal stability and worked well as a paraffin oil dispersant. CMC–oxalate provided a barrier around the oil droplet surface, which prevented droplets from coalescing. This hypothesis is supported by the contact angle measurement for the O/W emulsion formed by CMC–oxalate being 0°, which is lower than the value for emulsions formed by underivatized CMC, 37.20°. From transmission electron microscopy observations, O/W emulsions of paraffin oil were spherical in shape, and separated from each other by a distance of 30–100 nm. This study shows that CMC–oxalate can be prepared by a low‐cost method, yielding nanocellulose with characteristics that resemble CNFs and CNCs, thereby opening up new potential applications for cellulose nanomaterials.

Untangling the threads of cellulose mercerization

Naturally occurring plant cellulose, our most abundant renewable resource, consists of fibers of long polymer chains that are tightly packed in parallel arrays in either of two crystal phases collectively referred to as cellulose I. During mercerization, a process that involves treatment with sodium hydroxide, cellulose goes through a conversion to another crystal form called cellulose II, within which every other chain has remarkably changed direction. We designed a neutron diffraction experiment with deuterium labelling in order to understand how this change of cellulose chain direction is possible. Here we show that during mercerization of bacterial cellulose, chains fold back on themselves in a zigzag pattern to form crystalline anti-parallel domains. This result provides a molecular level understanding of one of the most widely used industrial processes for improving cellulosic materials.

Edge-On (Cellulose II) and Face-On (Cellulose I) Adsorption of Cellulose Nanocrystals at the Oil-Water Interface: A Combined Entropic and Enthalpic Process.

Nanocelluloses can be used to stabilize oil-water surfaces, forming so-called Pickering emulsions. In this work, we compare the organization of native and mercerized cellulose nanocrystals (CNC-I and CNC-II) adsorbed on the surface of hexadecane droplets dispersed in water at different CNC concentrations. Both types of CNCs have an elongated particle morphology and form a layer strongly adsorbed at the interface. However, while the layer thickness formed with CNC-I is independent of the concentration at 7 nm, CNC-II forms a layer ranging from 9 to 14 nm thick with increasing concentration, as determined using small-angle neutron scattering with contrast-matched experiments. Molecular dynamics (MD) simulations showed a preferred interacting crystallographic plane for both crystalline allomorphs that exposes the CH groups (100 and 010) and is therefore considered hydrophobic. Furthermore, this study suggests that whatever the allomorph, the migration of CNCs to the oil-water interface is spontaneous and irreversible and is driven by both enthalpic and entropic processes.

Cryogenic grinding of cotton fiber cellulose: The effect on physicochemical properties

The study evaluated the effect of cryogrinding, a relatively new, cost-effective, and sustainable mechanical treatment method, on physicochemical properties of two different micronaire (3.6- and 5.3-) cotton fiber cellulose. Native (type I), mercerized (type II), and acidulated cellulose were subjected to cryogrinding for 48 and 96 min, and their physicochemical properties were investigated. The results demonstrated that cryogrinding resulted in partial amorphization of native and mercerized celluloses, particle size decrease, and a slight reduction of T50%. Importantly, degree of polymerization (DP) of native cellulose reduced significantly: more than two-fold after 12 cycles and more than three-fold after 24 cycles of cryogrinding. No difference in properties was found between 3.6- and 5.3-micronaire cellulose. Advantageous impacts of cryogrinding found in this work will help signify the potential of this technique in cellulose processing and enable the identification of areas for future development.

Characterization of mercerized cellulose nanofibrils prepared by aqueous counter collision process

Cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) methods have amphiphilic Janus-type properties, which appear markedly for ACC–CNFs prepared from bacterial nanocellulose (BNC) pellicles. The amphiphilic Janus-type surface is exposed because of the mechanism involved in ACC pulverizing of cellulose materials, in which the predominant interactions of the (2 0 0) lattice plane of the cellulose I crystal structure are weak interplanar van der Waals interactions. Such selective cleavage is more likely to occur for highly crystalline BNC. This study focused on alkali-mercerized cellulose samples, which are of lower crystallinity than BNC. The mercerized raw materials were subjected to ACC treatments and their fiber morphologies, crystallinities, and surface properties were compared to those of ACC–CNFs from native samples. In particular, the Wide-angle X-ray diffraction (WAXD) results suggested that the cleavage was most likely to occur at the (1 1 0) plane in nanofibrils derived from cellulose II, unlike (2 0 0) lattice plane for the case of cellulose I. Accordingly, the entire results indicate that the properties of the ACC-treated mercerized CNFs differ greatly from those of conventional ACC–CNFs composed of cellulose I crystalline structure. This is presumably because ACC nanopulverization proceeds depending on the surface structure and crystalline morphology of the raw material.

Stepwise allomorphic transformations by alkaline and ethylenediamine treatments on bamboo crystalline cellulose for enhanced enzymatic digestibility

Efficient modification and decrystallization of cellulose Iβ in lignocellulosic biomass are potential ways to overcome biomass recalcitrance and facilitates enzymatic degradation. Herein, we have treated moso bamboo and microcrystalline cellulose separately by either alkali or ethylenediamine (EDA) treatments, as well as using both in succession. The pretreatments successfully transformed the initial cellulose Iβ allomorph into cellulose II, IIII, and cellulose IIIII. Crystal structures and crystallinities were determined by Rietveld X-ray diffraction and CP/MAS 13C NMR. Comparatively, the samples that were sequentially treated by EDA and NaOH had low crystallinity (~50%), larger d-spacings of ~4.4 Å for the hydrophobic (110) planes, and less condensed microfibrillar aggregation. The factors simultaneously contributed to as high enzymatic hydrolysis yield as 89.5% and 91.7% respectively, followed by the yields of mercerized cellulose II and cellulose IIIII allomorph. The stepwise allomorphic transformations may provide new strategies on improving efficiency of saccharification process and biomass utilization.

On the orientation of the chains in the mercerized cellulose

The cold alkaline treatment or mercerization of cellulose is widely used in industry to enrich the cellulose raw with high-molecular-weight alpha-cellulose. Washing out of hemicelluloses by alkalies is accompanied by the rearrangement of the cellulose chains’ packing, well known as a transition between cellulose I and cellulose II. Cellulose II can also be produced by the precipitation of the cellulose solutions (regeneration). The currently accepted theory implies that in cellulose II, both mercerized and regenerated, the macromolecules are arranged antiparallelly. However, forming such a structure in the course of the mercerization seems to be significantly hindered, while it seems to be quite possible in the regeneration process. In this work, we discuss the sticking points in the theory on the antiparallel structure of mercerized cellulose from a theoretical point of view summarizing all of the available experimental data in the field.

Isolation, modification and characterisation of cellulose from wild Dioscorea bulbifera

This study attempted to valorise wild Dioscorea bulbifera yam presently known to be poisonous and inedible obtained from three sources. The functional properties as well as its chemical composition were determined and isolated. Isolated cellulose was modified by the actions of sodium hydroxide and maleic anhydride. The biomass, isolated products and modified cellulose were characterized. Results showed that the highest cellulose obtained was 82.6%. FT-IR results showed successful modification of cellulose with the presence of a carbonyl (C = O) adsorption band at around 1725 cm-1. SEM images and XRD data showed a clear decrease in crystallinity but a slight increase in crystallite size after modification of the mercerized cellulose. TGA results showed the polymers degraded between 284 and 414 °C. The study reveals that the modified cellulose has potential application as an adsorbent and industrial material.

Oleogelation of rapeseed oil with cellulose fibers as an innovative strategy for palm oil substitution in chocolate spreads

Abstract The texturing properties of mercerized cellulose dispersed in rapeseed oil without any prior thermal treatment were investigated as a function of botanical origin, cellulose content, mass fraction and fiber size through a molecular analysis of samples, macroscopic/microscopic observations and rheological experiments (continuous and oscillatory shear flows). A solid-like behavior of dispersions was demonstrated for a minimum cellulose content of about 60wt% in the vegetal powder. The oleogelation efficiency increases with the mass fraction of powder in oil and the maximum size of cellulose fibers as a result of weak attractive interactions and fiber entanglement giving rise to a network entrapping the liquid phase. An innovative strategy using a 30wt% dispersion of bamboo fibers in rapeseed oil was finally used to produce in a conch a chocolate spread with a high thermal stability at 38°C and healthier nutritional qualities compared to an equivalent product prepared with palm oil.

Biodegradable cellulose I (II) nanofibrils/poly(vinyl alcohol) composite films with high mechanical properties, improved thermal stability and excellent transparency

Cellulose nanofibrils (CNFs) with cellulose I and II allomorphs were efficiently prepared by sulfuric acid hydrolysis of eucalyptus cellulose under three different conditions followed by mechanical treatments: (i) classical sulfuric acid hydrolysis of cellulose I (CNF-I), (ii) sulfuric acid hydrolysis of mercerized cellulose II (MNF-II), and (iii) solubilization and hydrolysis of cellulose I by concentrated sulfuric acid and subsequent recrystallization in water (RNF-II). Crystal structure, surface chemistry, morphology and thermal properties of three CNFs were investigated and compared. Three CNFs of 2–10 wt% were mixed with PVA to prepare biodegradable composite films. CNF allomorph had significant impact on crystal structure, mechanical and thermal properties of the PVA composites. The maximum Young's modulus of CNF-I/PVA, RNF-II/PVA and MNF-II/PVA were increased by 62, 32 and 44%, respectively. Addition of CNFs raised onset degradation temperature (Tonset) and thermal decomposition temperature (Tmax) of PVA nanocomposite, while decreased the melting temperature (Tm). Temperature window (Tonset − Tm) for the melt processing of nanocomposites (10 wt% CNF loading) were increased 2.8, 3.2 and 2.5 times for CNF-I/PVA, RNF-II/PVA and MNF-II/PVA, respectively. All composite films remained excellent transparency with addition of CNFs. This comparative study provided important knowledge of selecting CNF allomorph for fabrication of high-performance CNF/PVA composites.

An Integrated Approach to Optimizing Cellulose Mercerization.

An integrated approach, based on quantitative transmission mode powder X-ray diffraction (PXRD) combined with multivariate statistical analysis, has been applied to cellulose obtained from three different sources to correlate the mercerization degree and crystallinity with the cellulose type, temperature, and reaction time. The effects of the experimental conditions on the two outcomes were studied by design of experiments (DoE) and surface responding analysis (SRA) combined with principal component analysis (PCA). SRA showed a marked influence of the type of cellulose (wood cellulose from the kraft vs. sulfite process, WCK vs. WCS) on the conversion of cellulose I to cellulose II (CII%) during mercerization. A counterintuitive simultaneous effect of temperature and cellulose type was also highlighted. The data elaboration in the form of response surface plots provided an easy predictive tool for the optimum conditions to maximize the conversion. The simulation reported for WCK showed maximum conversion (96%) at 70 °C in 24 h with 18%wt NaOH.

Chemical Modification of Cotton Cellulose by Carbamation with Urea and Its Dyeability with Reactive Dyes without the Use of Electrolyte

ABSTRACT Dyeing of cotton cellulose is done mostly with reactive dyes which form a strong covalent bond with the substrate. Reactive dyeing process requires a high amount of salt and alkali. Studies have been made to improve the exhaustion and reduce the use of a high amount of salt and alkali by cationization of the substrate. This study focuses on the carbamation of mercerized cotton cellulose for the purpose of preparing an alternative way of dyeing cotton fabric with Reactive dye in the absence of electrolyte. The effect of carbamation was shown by FTIR spectra qualitatively, where the optimal results were with urea concentration of 400 g/l, temperature of 135°C and time of 5 minutes. The carbamated cotton showed lower decomposition temperature than that of native cotton. The color strength, exhaustion, fixation and total dye utilization studies show good results compared to dyeing conventional cotton fabric.

Mercerization effect on structure and electrical properties of cellulose: Development of a novel fast Na-ionic conductor

Mercerized cellulose (alkali cellulose C6H10O5* NaOH) was obtained by treatment of cotton linters (cellulose) with aqueous sodium hydroxide. Cellulose and alkali-cellulose samples with relative density of 78% and 79% were obtained after sintering the material in air at optimal sintering temperatures of 423 K and 473 K, respectively. The electrical properties of the samples were studied by impedance spectroscopy in the frequency range from 13 MHz to 50 Hz at temperatures between 393 K and 493 K. The influence of cellulose mercerization on electrical properties of cotton linters was observed. The cellulose behaves like an electrical insulator. Contrariwise, the alkali-cellulose is a fast-ionic conductor with a conductivity value of σ473 K = 3.22 × 10−6 S cm−1 having activation energies of 0.49 eV and 0.68 eV at temperature range of 393 K–458 K and 459 K–500 K, respectively. The change of activation energy value has been discussed in relation to thermal stability.

INFLUENCE OF PRETREATMENTS ON CRYSTALLINITY AND ENZYMATIC HYDROLYSIS IN SUGAR CANE RESIDUES

ABSTRACT This research evaluated the effect of different delignification pretreatments (enzymatic and organosolv), on the crystallinity and enzymatic hydrolysis of harvested sugar cane residues. The Crystallinity Index (CrI), the Relative Number of Intensity (Ir), the degree of cellulose mercerization (IIC-%), and the Global Index of Saccharification (GIS) were used as measurement parameters for six different substrates obtained from sugar cane residues (tops and leaves) by different processes. In this characterization, the spectroscopic ty Techniques of Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction and scanning eElectron microscopy (SEM) were used. Substrates to which only organosolv pretreatment was applied, without any further treatment, presented good behavior for the enzymatic hydrolysis and a high CrI, possibly due to the increase of the crystallinity by elimination of amorphous material.

Changes in the Physicochemical Characteristics of Cellulose upon Its γ-Irradiation and the Subsequent Mercerization

Changes in the molecular-weight distributions of low-molecular-weight and alkali cellulose after the processes of γ-irradiation and mercerization of cellulose have been studied. The features of the dissolution of irradiated cellulose in an alkaline solution during mercerization have been revealed. It has found that the alkali cellulose produced from the irradiated polymer has increased homogeneity of the molecular-weight distribution. The γ-irradiation of cellulose before mercerization leads to an increase in the reactivity of the polymer in the xanthogenation reaction by 30–50%. An optimum range of absorbed doses for the radiation pretreatment of cellulose prior to a viscose production process has been determined.

Suppression efficacy of lignosulfonate/mercerized cotton fiber composite against cancer cell’s activities

Lignosulfonate (LS)/mercerized cotton composite was prepared to study the LS suppressive possibility to control malignant cell activities to facilitate chemotherapy treatment. The composite was characterized by cross-polarized/magic angle spinning 13C nuclear magnetic resonance (NMR) spectrometry and scanning electron microscope (SEM). 13C NMR spectra and SEM indicated that the presence of LS increased crystallinity and porosity of mercerized cellulose, respectively. Furthermore, the composite efficacy against cancer cell activity was evaluated by cytotoxicity for malignant cell line HCT116, HepG2, and MCF-7. The cancer cells thrive in an acidic environment and they do not survive in normal or alkaline media. The release of LS was intended at acidic pH, in which, the acidity increased due to the activity of the cancer cells that activate the LS released from the mercerized cotton into the media. Therefore, this release process reduced the activity of cancer cells. The released LS kept cancer cells in a low activity via decreasing acidity. Hence, the composite may not eliminate the cancer cells, but it reduces the activity of cancer cells.

Step–wise multi–scale deconstruction of banana pseudo–stem (Musa acuminata) biomass and morpho–mechanical characterization of extracted long fibres for sustainable applications

Banana Pseudo–stem (BPS) is an annual renewable agricultural by–product with a potential for valorization in the production of paper, textile fibre or new bio–based materials. A gradual deconstruction process was implemented to determine BPS chemical composition and isolate sub–components that may be valorized in the formulation of bio–based polymer composites. At each step, the residues were analyzed by FTIR, X–ray diffraction and TGA–DTG. The chemical composition of the starting material (% of dry weight) was evaluated as: 13.4% total extractives, 6% pectins, 14.7% lignins, 28% hemicelluloses and 38% cellulose. The deconstruction process for BPS was efficient but led to mercerized cellulose (cellulose II) as a final residue, as assessed by the intense X–ray scattering peaks centered at 20.5° and 21.5°. Cellulose II formation was induced by the high concentration of the alkaline KOH solution used to dissolve hemicelluloses in holocellulose. The step–wise removal of non–cellulosic sub–components led to a more thermally stable residue. Long fibres were also obtained from BPS at a yield of 60%. These fibres display cellulose I structure and a thermal stability similar to the extracted cellulose. SEM analyses of long fibres showed transversal and lateral defects, the presence of surface hairiness and an almost cylindrical morphology. Uniaxial tensile tests were carried out at room temperature on 150 specimens randomly chosen among the less hairy fibres, with diameters ranging from 40 to 140 μm. Mechanical investigations (Young modulus: 6.3–26 GPa; nominal stress at break: 140–768 MPa; nominal strain at break: ∼3%) reveal a significant disparity strongly influenced by fibre diameter, except for the nominal strain at break which remains fairly constant around 3%. These results are comparable to the upper range of the values reported for fibres extracted from BPS through alternative chemical routes or for fibres obtained from other annual plants such as jute and hemp.

Application of cellulose-immobilized riboflavin as a redox mediator for anaerobic degradation of a model azo dye Remazol Golden Yellow RNL

This study described the anaerobic degradation of the azo dye Remazol Golden Yellow RNL (RGY-RNL) using cellulose-immobilized riboflavin (MC 3) as the redox mediator. This new solid support containing immobilized riboflavin was synthesized from succinylated mercerized cellulose, and was characterized by elemental analysis, FTIR, and solid-state 13C NMR. MC 3 was resistant to pH 2–9, and anaerobic degradation of RGY-RNL using MC 3 in the presence of anaerobic sludge yielded a zero order degradation rate constant (k0,obs) equal to 0.189mg/Lh, which was 56% better than experiments carried out without a redox mediator. Color removal efficiency after 48h of degradation averaged 89.4% in experiments with MC 3 and 72% without the addition of a redox mediator. These results showed that MC 3 can be used to immobilize redox mediators, allowing reduction of wastewater treatment costs.