Bleached Bagasse Research Articles

Short Synthesis Time and Characterization of Dialdehyde Carboxymethyl Cellulose (DCMC) from High Bagasse Carboxymethyl Cellulose (CMCB) Concentration

ABSTRACT Bagasse is a type of bast fiber obtained from agricultural waste. It is a suitable material for producing cellulose derivatives, specifically as a DCMC crosslinking agent. The optimal synthesized conditions of dialdehyde carboxymethyl cellulose (DCMCB) from the elemental chloride-free (ECF) bleached bagasse pulp were evaluated, including the concentration of bagasse carboxymethyl cellulose (CMCB) at 3% and 6% (w/v), the sodium periodate (NaIO4) concentration at 5%, 10%, and 15% (w/v) and the reaction time from 1 to 4 hours. The optimal conditions were characterized based on the DCMCB properties, including production yield, aldehyde content, and degree of oxidation. The optimal conditions for synthesizing DCMCB are a pH of 3.0, a reaction temperature of 35°C, a NaIO4-to-CMCB mass ratio of 1:6, and a reaction time of 2.5 hours. It obtained 97.37% yield and 97.70% aldehyde content. This optimal condition led to a 27.2% significant increase in DCMCB aldehyde content and a 37.5% reduction in reaction time. Various analytical techniques were employed to verify the success of CMCB oxidation and to fully characterize the crystallinity, thermal stability, and structure of DCMCB. CMCB encountered oxidation, resulting in alterations in functional groups and influencing the crystallinity, thermal stability, and structure of DCMCB.

Soda pulping of sunn hemp (Crotalaria juncea L.) and its usage in molded pulp packaging

Petroleum-based materials are often used in the packaging industry. However, the single use value of such products can be problematic with regard to proper waste disposal. As such, molded pulp packaging can be used as an alternative, given its ease of recycling, composting, and eventual biodegradation. In this work, we aims to study the pulp properties of sunn hemp and its usage as molded pulp products. For this purpose, unbleached beaten and unbeaten soda pulps derived from the whole stem of sunn hemp were examined for their fiber morphology, fibrillation, fiber classification, and physical properties. The sunn hemp pulp was subsequently molded using a batch molding machine. To determine the hydrophobicity of the molded pulp products, the molded samples were manufactured with and without additives. Finally, some properties of the molded pulp products were examined and compared with the commercially available bleached bagasse molded pulp products. It was observed that the molded products made from sunn hemp pulp with additives had a higher water contact angle than that of the commercial products. In terms of general usage, the molded products from sunn hemp pulp with additives were found to be capable of storing hot water, hot cooking oil, as well as microwaving water. We concluded that the sunn hemp pulp could be used as an alternative fibrous raw material in the production of molded pulp packaging.

Surface modification of cellulose originated from different plant sources through TEMPO/Laccase/O2 oxidation

An environmentally friendly 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation system using halogen-free reagents has attracted much attention. At present, cellulose nanofibers (CNFs) with a high carboxyl content can be prepared by TEMPO/laccase/O2 (TLO)- oxidation of hardwood bleached kraft pulp (HBKP) under aqueous conditions, while, the related research is still in its infancy. For example, the further applications of TLO-CNFs and the oxidation effect of the TLO system on cellulose from different sources have not been studied. In this work, cellulose from four different sources, that is, HBKP, softwood bleached kraft pulp (SBKP), bleached bagasse sulfate pulp (BBSP) and microcrystalline cellulose (MCC), was oxidized by using a TLO-oxidation system. All cellulose materials were found to be able to be oxidized successfully regardless of the source, which proved the universality of the TLO-oxidation system. Different from traditional TEMPO/NaBr/NaClO (TBN)-oxidation that introduces major carboxyl groups (0.846–1.154 mmol/g) and minor aldehyde groups (0.041–0.097 mmol/g) to cellulose, carboxyl (0.558–0.615 mmol/g) and aldehyde (0.218–0.235 mmol/g) groups can both be sufficiently introduced on the surface of TLO-oxidized cellulose. Based on the aldehyde groups introduced, the wet strength of the TLO-oxidized cellulose handsheet was greatly improved to 400% of the non-oxidized one due to the formation of hemiacetal linkages. In addition, oxidized cellulose can be isolated to homogeneous TLO-CNFs or TLO-cellulose nanocrystals (CNCs), and TLO-CNFs (CNCs) can easily be processed into films and hydrogels with high light transmittance and excellent mechanical properties. Remarkably, compared to the other TLO-CNFs, TLO-CNFs (BBSP) has higher aspect ratio with thinner width (nanofibers as thin as 2 nm can be achieved). Thus, the mechanical properties of TLO-CNFs (BBSP) assembled films and hydrogels were superior to others. These all providing significance and promising prospects for the applications of TLO-oxidation systems, meantime, the distinctive characteristics of TLO-CNFs (BBSP) were explored.

Synthesis of Myrtenal-Based Nanocellulose/Diacylhydrazine Complexes with Antifungal Activity for Plant Protection

In search of novel bioactive compounds with excellent and broad-spectrum antifungal activity and nanopesticides with sustained releasing property, a series of novel myrtenal-based diacylhydrazines were designed, synthesized, and characterized. The preliminary bioassay showed that myrtenal-based 2-picolinyl hydrazide exhibited better or comparable antifungal activity than that of the commercial fungicides boscalid and chlorothalonil against the tested fungi. Furthermore, myrtenal-based nanocellulose was designed as a nanopesticide carrier and prepared from two biomass materials, bleached bagasse pulp and turpentine oil. Drug-loading capacities (LCs) of these carriers and sustained releasing properties of corresponding complexes were also evaluated, and the results indicated that the esterification reaction in the different solvents would affect the micromorphology of carriers, which was the important influential factor for loading or releasing drugs. To our delight, complex VIII-3 (LC = 0.32, total releasing amount/time = 99.8%/168 h) showed a macroporous framework with the drug evenly distributed across the opening network and staged drug-releasing performance that deserved further study as a nanopesticide.

Effects of Porosity on the Static Compression of Foam Buffer Materials of Plant Fiber and Their Numerical Model

In recent years, researchers have investigated plant fiber foam buffer package materials for their environmental advantages, which include their ability to completely biodegrade and their rich raw materials. The porosity of buffer materials is an important factor that affects a plant’s static compression property. In this study, foam buffer package materials of plant fiber were developed using bleached bagasse pulp as the main raw material. A digital microscope was used to observe the porosity structures of the foam buffer materials, and the porosity was calculated via binary image processing using Matlab software. The effects of porosity on the static compression properties of cushion materials were discussed, and a numerical model was established. The results indicated that the threshold value chosen affected the calculation of the porosities of buffer materials, which in turn have significant effects on their specific static compression properties. The variation trend of the stress-strain curve fits the hyperbolic tangent function, according to which a numerical model was established. The results of this experiment were in accordance with the theoretical values, which will support the theoretical design of foam buffer package materials of plant fiber.

Developed Chitosan/Oregano Essential Oil Biocomposite Packaging Film Enhanced by Cellulose Nanofibril.

The use of advanced and eco-friendly materials has become a trend in the field of food packaging. Cellulose nanofibrils (CNFs) were prepared from bleached bagasse pulp board by a mechanical grinding method and were used to enhance the properties of a chitosan/oregano essential oil (OEO) biocomposite packaging film. The growth inhibition rate of the developed films with 2% (w/w) OEO against E. coli and L. monocytogenes reached 99%. With the increased levels of added CNFs, the fibrous network structure of the films became more obvious, as was determined by SEM and the formation of strong hydrogen bonds between CNFs and chitosan was observed in FTIR spectra, while the XRD pattern suggested that the strength of diffraction peaks and crystallinity of the films slightly increased. The addition of 20% CNFs contributed to an oxygen-transmission rate reduction of 5.96 cc/m2·day and water vapor transmission rate reduction of 741.49 g/m2·day. However, the increase in CNFs contents did not significantly improve the barrier properties of the film. The addition of 60% CNFs significantly improved the barrier properties of the film to light and exhibited the lowest light transmittance (28.53%) at 600 nm. Addition of CNFs to the chitosan/OEO film significantly improved tensile strength and the addition of 60% CNFs contributed to an increase of 16.80 MPa in tensile strength. The developed chitosan/oregano essential oil/CNFs biocomposite film with favorable properties and antibacterial activity can be used as a green, functional material in the food-packaging field. It has the potential to improve food quality and extend food shelf life.

In situ mineralization of nano-hydroxyapatite on bifunctional cellulose nanofiber/polyvinyl alcohol/sodium alginate hydrogel using 3D printing

This paper reports the manufacturing by 3D printing of scaffolds for in-situ mineralization of hydroxyapatite using aqueous suspensions of alginate and polyvinyl alcohol (PVA)-grafted cellulose nanofibers (CNF). Bifunctional CNF with carboxyl and aldehyde moieties were prepared from bleached bagasse pulp and crosslinked with PVA. Aqueous hydrogels for 3D printing were prepared by directly mixing PVA-grafted CNF with sodium alginate, with and without the addition of phosphate ions. A calcium chloride solution was sprayed during the printing process in order to partially crosslink alginate and to increase the dimensional stability of the printed gel. At the end of the printing process, the prepared scaffolds were dipped into a CaCl2 solution to: i) complete alginate crosslinking and ii) promote hydroxyapatite nucleation and growth by reaction with phosphate ions. In order to better understand the mechanisms governing manufacturing of scaffolds by 3D printing, the rheological behavior of alginate/PVA-grafted CNF and the mechanical properties of unit filaments obtained by direct hydrogel extrusion were investigated. The final scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). This study shows that 3D printed sodium alginate/PVA-grafted CNF hydrogels are promising scaffold materials for bone tissue engineering.

Magnetic paper from sugarcane bagasse fibers modified with cobalt ferrite nanoparticles

Magnetic paper sheets were prepared from bleached sugarcane bagasse fibers and cobalt ferrite nanoparticles by lumen loading method. Sugarcane bagasse is an important fibrous raw material widely used worldwide for papermaking, whereas cobalt ferrite nanoparticles is an appropriate material for fibers modification given their magnetic properties. Cobalt ferrite nanoparticles were synthetized by coprecipitation method and coated with silica by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) molecules. Then, silica coated magnetic nanoparticles were functionalized with polyethylenimine (PEI), as retention aid, by electrostatic bonding. It was observed that the loading degree of magnetic fibers depends on nanoparticles concentration and PEI dosage, which was determined by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) shows the deposition of coated nanoparticles on the surface and into macropores of fibers. All samples exhibited ferromagnetic behavior. The coercivity values of magnetic fibers are higher than 0.2 kOe. This indicates that these fibers could be used to produce paper for magnetic recording purposes. Magnetic papers with 10 and 20% of modified fibers were manufactured. Brightness and tensile index of papers were decreased with the rise of loading degree. CIEL*a*b analysis shows the color differences between unmodified and modified papers.

Tuning of size and properties of cellulose nanofibers isolated from sugarcane bagasse by endoglucanase-assisted mechanical grinding

This study explores the possibility of producing tunable cellulose nanofibers (CNFs) with a wide range of size and properties from sugarcane bagasse in an energy-efficient manner, which is very meaningful for specific application of CNFs. The bleached bagasse kraft pulp was subjected to endoglucanase pretreatment with a wide range of enzyme dosage followed by mechanical grinding to obtain size-tunable CNFs. The size distribution and structural characteristics of CNFs, energy consumed during the CNF production process, and properties of CNF films were systematically investigated as a function of the enzyme dosage applied in the pretreatment. The results showed that endoglucanase-assisted mechanical grinding was able to produce CNFs with controllable length (298–4500 nm) and diameter (9–26 nm), meanwhile improving CNF yield and energy-efficiency. The controllable range of CNF length was extremely wide based on our best knowledge. The optical performance and mechanical properties of the prepared CNF films could be effectively tuned by regulating the structural characteristics of the CNFs. Moreover, all the as-prepared CNFs retained high thermal stability. The tailor-made CNFs from sugarcane bagasse are expected to provide compatibility with various CNF-related applications.

Optical Recognition of Ammonia and Amine Vapor Using "Turn-on" Fluorescent Chitosan Nanoparticles Imprinted on Cellulose Strips.

A practical fluorescent test dipstick for an efficient recognition of ammonia and amines vapors was developed. The prepared testing strip was based on a composite of molecularly imprinted chitosan nanoparticles, supported on cellulose paper assay, with artificial fluorescent receptor sites for ammonia/amines recognition in aqueous and gaseous phases. A modified chitosan nanoparticles containing fluorescein molecules, were successfully prepared and employed on cellulose paper strip creating fluorescent cellulose (FL-Cell) to act as "turn-on" fluorescent sensor for sensing and determining ammonia and organic amine vapor. We employed chitosan nanoparticles that had fluorescein incorporated as the fluorescent probe molecule, with a readout limit achieved for aqueous ammonia as low as 280ppm at room temperature and atmospheric pressure. The sensor responded linearly relying on the aqueous ammonia concentration in the range of 0.13-280ppm. The chromogenic fluorescent cellulose platform response depended on the acid-base characteristic effects of the fluorescein probe. The protonated form of fluorescein molecules immobilized within the chitosan nanoparticles were in a nanoenvironment demonstrating only weak fluorescence. When binding to ammonia/amine vapor, the fluorescein active sites were deprotonated and exhibited higher "turned-on" fluorescence as a result of exposure to those alkaline species. The simple fabrication and abovementioned characteristics of such fluorescent chitosan nanoparticles are such that they should be applicable for monitoring of ammonia/amines in either aqueous or vapor states. We studied the distribution of the fluorescent chitosan onto paper sheets fabricated from bleached bagasse pulp and coated with two different thicknesses of a fluorescent nanochitosan and blank nanochitosan solutions. A thin fluorescent nanochitosan layer was created on the surface of cellulose strips using an applicator. Its distribution was assessed by scanning electron microscopic (SEM) and transmission electron microscopic (TEM) analysis as well as Fourier-transform infrared spectroscopic (FT-IR) measurements. The mechanical properties were also tested. The exploitation of this "turn-on" fluorescence sensor invented platform should be amenable to different situations where determination of ammonia/amine vapor or aqueous solution is required.

Development of an active polylactic acid (PLA) packaging film by adding bleached bagasse carboxymethyl cellulose (CMCB) for mango storage life extension

This study aimed to determine the properties of a new active packaging film in order to extend the storage life of fresh mangoes by packing “Nam Dok Mai” mangoes (Mangifera indica Linn) with an active packaging film composed of biodegradable polymer and cellulose derivatives. A new packaging bag was produced primarily by blending polylactic acid (PLA) with spray‐dried carboxymethyl cellulose (CMC) from bleached bagasse (CMCB) at various concentrations (0%, 1%, 2%, and 4% w/w). The film thickness of the PLA and PLA/CMCB bags was 75 μm. Unpacked mangoes were used as control before the packaged ones were stored at export conditions (13 ± 1°C and 90 ± 5% relative humidity [RH]) to evaluate the efficiency of the PLA/CMCB film. Mango respiration and ethylene production rate were measured periodically in a packaging atmosphere as an indicator of ripeness. Changing fruit physio‐chemistry parameters were also studied, including weight loss, peel and flesh colour, firmness, total soluble solid (TSS), and total acidity (TA). The capacity of PLA/CMCB packaging to absorb water vapour and prolong mango shelf life was demonstrated, and active packaging function by control of RH was also demonstrated. The absorption of PLA/CMCB packaging was increased dramatically at 4% (w/w) CMCB mixed with PLA. At this CMCB concentration, the packaging film could extend the shelf life of mangoes for 42 days in export condition as well as decrease the physio‐chemistry parameters and respiratory rate, which were significantly enhanced when compared with those of control mangoes or unpacked mangoes (P ≤ 0.05), which had a shelf life of approximately 3 weeks.

MODIFIED STARCH AS ADDITIVES TO IMPROVE TISSUE PAPER PROPERTIES

Our research tries to share solutions of the problems that faced who are working in the papermaking industries, especially the retention of the filler, fine fibers, drainage and machine run ability, besides paper strength, softness, smoothness and the increase in the absorption properties of the tissue paper. Starch, which is the most widely used as strengthening agent in papermaking, was modified in the current work with urea, caustic soda and were added to the pulp paste in ratios of 5 to 20 ml. On the other hand, the starch-caustic soda was further modified with trimethylamine hydrochloride in the presence of epichlorohydrin (ECH) as a cross-linker and was also added in the same above ratios to the pulp paste. Another modification was made to the starch which was polymerized with acrylic acid to give hydrogel which was added to the pulp paste in a tiny amount, i.e. 0.001g, and in the same manner, the bleached bagasse pulp was polymerized and added to the pulp paste. The results showed an improvement of the strength, softness, smoothness, stiffness, absorption and zeta potential compared to the blank, enabling them to be promising for making tissue paper or absorbing paper. The research also approaches the environmental address since the bagasse considered as a renewable and sustainable resource coming from agricultural residue (sugarcane) which lead to the decrease in both their environmental impact and economic cost.

Effects of the Solids Content of TEMPO-oxidized Cellulose Prior to Freeze-drying on the Properties of the Dried Materials

Porous material was prepared by freeze drying of oxidized cellulose microfibrils. Oxidized microfibrillated cellulose was obtained by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-mediated oxidation of bleached bagasse pulp and lapping process, and the influence of cellulose microfibril concentration on the material properties was studied from oxidized cellulose microfibrils within a range of solids concentrations of aqueous suspension. The microscopic morphology, pressure intensity, specific surface area, and pore size were analyzed by scanning electron microscopy (SEM), universal material testing machine, fully automatic specific surface area, and porosity analyzer (BET). The surface elemental composition of the materials was analyzed by X-ray photoelectron spectroscopy (XPS). Results showed that the strength of the porous materials increased with increasing concentration of oxidized cellulose microfibrils, along with decreases of porosity decreases, and increases of specific surface area and pore volume. A higher mass fraction resulted in a smaller pore size of the porous scaffold material and more structure of the material. However, when the concentration reached a certain value, some fiber flocculation occurred.

Effects of D-hot pretreatment on micro-distribution of residual lignin in sugarcane bagasse pulp and fiber properties

Pretreatment of sugarcane bagasse pulp by hot chlorine dioxide has been performed to study delignification and structural changes in lignocelluloses. The compositions of the products were measured by gas chromatography mass spectrometry. The structure and morphology of the D-hot pretreated sugarcane bagasse pulps were characterized by FTIR, scanning electron microscope, X-ray diffraction, Metso Kajaani FS300 fiber analyzer and optical analyzer. Temperature played a crucial role in the lignin depolymerization and hemicellulose hydrolysis. The results show that the lignin content was reduced by 28.39% in the P layer and 20.93% in the S layer with increasing temperature from 60 to 95 °C. The resulting compositions of D-hot stage effluent were mainly including oxidized lignin and derivatives of furfural. Compared with the control, the category of oxidized lignin can be increased with D-hot pretreatment. Also, pretreated bagasse pulp has high brightness of 59.71% ISO, crystallinity index of 70.84%, L/W of 50.84 and outstanding optical properties. Therefore, bleached bagasse pulps might have the opportunities for further application in paper and paper-based materials. The graphical abstract showed that the changes of the crystallinity index (CrI), the brightness, and the L/W of the SCB pulp fibers with increasing reaction temperature from 60 to 95 °C. Also showed that the cross section of the single fiber and the region of P and S layer. EDS images of P and S layers for the unbleached SCB pulp, control pulp and D-hot bleached SCB pulps, the peaks corresponding to elemental carbon and oxygen were shown for the samples. In EDS, oxygen/carbon atom ratios and lignin mass in P and S layer of the unbleached pulp and bleached pulps were determined. The degradation products of lignin (1)–(3) in the control and degradation products (2)–(15) in the D-hot effluent were identified.

Adsorption of methylene blue from aqueous solutions by cellulose and nanofiber cellulose and its electrochemical regeneration

This study was conducted to evaluate the potential of the bleached bagasse, cellulose, and nanofiber cellulose to remove methylene blue (MB) from aqueous solution. The morphology of adsorbents surface and their functional groups were examined by using scanning electron microscope and Fourier transform infrared spectroscopy techniques, respectively. In a batch mode study at 25°C temperature, the effects of initial dye concentration, contact time, adsorbent dose, and solution pH on adsorption performance were investigated. The results showed that the percent of MB removal increases by increasing pH and also by increasing sorbent dosage and decreasing initial dye concentration. The adsorption kinetics and equilibrium data were in good agreement with the pseudo-second-order kinetic model and Freundlich adsorption isotherm, respectively. The removal of MB was better and more effective with cellulose and cellulose nanofiber as compared with the bleached bagasse. The regeneration of cellulose and nanofiber cellulose loaded with MB was investigated using electrochemical method under different operating conditions. The results showed that the electrochemical process efficiency is more than 60 for regeneration adsorbents. © 2018 Desalination Publications. All rights reserved.

Isolation and surface modification of cellulose nanocrystals from sugarcane bagasse waste: From a micro- to a nano-scale view

This work presents the isolation and functionalization of cellulose nanocrystals (CNCs) extracted from sugarcane bagasse (SCB). CNCs were obtained by acid hydrolysis of bleached bagasse pulp and functionalized with adipic acid. The results showed that unmodified CNCs exhibit both a high crystallinity index and a significant aspect ratio. Surface modification with adipic acid decreases the nanocrystal dimensions due to removal of the amorphous region between the crystalline domains and also changes the electrostatic repulsion and hydrophilic affinity of CNCs. Unmodified CNCs offer potential applications as reinforcing phase in hydrophilic polymeric matrices, while modified CNCs interact better with hydrophobic matrices. The use of CNCs as reinforcement in polymer nanocomposites expands the application of this renewable material and increases its added value, providing nonenergy-based markets for the main biomass of the sugarcane industry.

Mechanical and barrier properties of spray dried carboxymethyl cellulose (CMC) film from bleached bagasse pulp

In this work, the spherical shape of carboxymethyl cellulose (CMC) tiny particles with high purity was successfully produced. Carboxymethyl cellulose from bleached bagasse pulp (CMCB) was synthesized at various alkaline concentrations from 20%(w/v) to 60%(w/v) and then the spray drying process was utilized as a simultaneous shape forming and purification step to obtain CMC microspheres without remnants of cellulose fibers. The alkalization of the bleached bagasse cellulose for carboxymethylation had no significant effect on the degree of substitution (DS), which was approximately 0.80. Increasing alkaline concentration influenced the properties of the CMC microsphere; e.g. increasing%NaCl and resulted to degrade cellulose fiber as observed by the gradual decreasing of%yield, %CMC, density, crystallinity and particle size. The morphology of CMCB microspheres revealed more crack marks on the surface and their granule sizes were smaller (0.10–0.15μm) when adding 40–60% (w/v) NaOH concentrations. The CMCB spray dried microspheres were cast to CMC films and their physical, mechanical and barrier properties were further investigated to determine the proper alkaline concentration for mercerization step. The CMCB film of microphere using 40%(w/v) NaOH showed the highest tensile strength (53.7MPa) as well elongation at a break of 3.09%. Increasing alkaline concentration coupled with the use of the spray drying process resulted in decreasing film viscosity but increasing CMCB film’s water solubility, tensile strength and elongation (up to 40%, w/v of NaOH concentration), water vapor and oxygen gas transmission rates (WVTR and OTR). The WVTR and OTR of CMCB film were reported to be in the range of 14.25–16.76g/m2day and 1.94–5.50×10−4cm3/m2dayPa, respectively. This led to a development of a high CMCB film value.

Comparative study of cellulose nanofiber blending effect on properties of paper made from bleached bagasse, hardwood and softwood pulps

Cellulose nanofibers (CNFs) offer the motivational prospective for a native fibrous constituent that can exceed the mechanical performance of plant fibers in current use for commercial products. In this research work, CNFs were prepared with an increased extent of mechanical refining from bleached bagasse, hardwood and softwood pulp fibers. These prepared CNFs were investigated by using the FE-SEM technique. During the increased refining process, partial fibrillation on the fiber surfaces was created, and these fibers were converted from the micro- to nano-scale through nanofibrillation. This shows the significant effect on the tensile, burst and tear strengths of paper made from unrefined and refined fibers. However, the optical properties remained almost constant with increases of the percentage of CNF and decreased significantly with increases of the refining intensity due to fiber damage. The strength properties of reinforced paper sheets were greater than those of paper sheets without reinforcement. The main drawback of this process is that the drainage time is longer with an increasing percentage of CNF in refined and unrefined pulp fibers.

Cellulose Nanocrystals Prepared by Persulfate One-Step Oxidation of Bleached Bagasse Pulp

This article describes a novel one-step method to prepare cellulose nanocrystals (CNCs) from bleached bagasse pulp via ammonium persulfate (APS) oxidation. The obtained persulfate oxidation cellulose nanocrystals (POCNs) were characterized for their microstructure, crystal properties, and chemical composition. The POCNs were successfully prepared with a total yield of 44.6%. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements indicated that the POCNs had an average length of 150 to 300 nm and an average width of 10 to 30 nm, as well as a rod-like morphology. Fourier transform infrared (FTIR) spectroscopy confirmed the introduction of carboxyl groups on the surface of cellulose. The X-ray diffraction (XRD) spectra proved the existence of cellulose type I, with a highly crystalline nature (79.2%), and thermogravimetric analysis (TGA) showed that the thermal stability decreased.

The Fluidization Properties of Bagasse Pulp Suspensions in a Rotary Device

Suspensions of bleached bagasse pulp at 0% to 15% mass concentrations were sheared in a concentric cylinder rotary device to study the pulp suspension’s fluidization properties. The use of a baffled chamber, with blade rotors, imposed shear stress within the suspensions and prevented slip at the chamber walls. Linear-type, hollow-type, and screw-type rotors were used to explore the influence of rotor structure on fluidization properties. The torque was measured as a function of rotational speed. The torque vs. rotational speed curves and flow phenomenon were found to depend on the mass consistency of the pulp suspensions and the gap between the rotor and chamber. The structure of the rotor had little influence on the fluidization of the pulp suspensions, and the critical rotational speed that makes the pulp suspensions turbulent was similar for all rotor types. The gap between the rotor and chamber should be small to let pulp suspensions fluidize at low rotational speed.