Cellulose Crystallinity Index Research Articles

Synergistic deinking effect of neutral sodium sulfite with fungal hemicellulase enzyme for improved recycling of waste papers

The study examined the beneficial effects of the synergistic deinking and delignification process on the quality of recycled pulp. By utilizing a mixture of neutral sodium sulfite, sodium carbonate, and fungal hemicellulase enzyme, the research demonstrated that the paper achieved enhancements in brightness, whiteness, tensile and burst indices, while also exhibiting reduced yellowness and ERIC in comparison to paper derived from chemically deinked pulp. The high-resolution ESCA analysis demonstrated a reduction in lignin surface coverage, and enhancement in the O/C atomic ratios. FTIR spectra indicated notable alterations in the structure of fibers and the functional groups of deinked pulp fibers. XRD spectra confirmed a higher cellulose crystallinity index and FESEM micrographs illustrated a rougher surface with the emergence of new fibrils. Additionally, UV analysis of the pulp effluents indicated significant lignin absorbance, while post-bleaching with H2O2 further enhanced the reactivity of the pulp and the overall quality of the paper.

Integrated formic acid and deep eutectic solvent mediated sustainable synthesis of cellulose nanocrystals from Sterculia foetida shells

The present study reports the green synthesis of cellulose nanocrystals from the shells of Sterculia foetida (SFS) cellulose. Three different methods, alkali, acid and organic acid, were screened for the maximum cellulose extraction. A maximum cellulose yield, 30.6 ± 0.84 w/w, was obtained using 90% formic acid at 110 °C in 120 min. The extracted cellulose was characterized and identified by instrumental analyses. SEM analysis showed skeletal rod-like microfibril structures and similar intra-fibrillar widths. CP/MAS 13C NMR and FTIR spectrum revealed the purity of cellulose and the absence of other components like hemicellulose and lignin. XRD study revealed a cellulose crystallinity index of 88.07%. BET analysis showed a good surface area (3.3213 m2/g) and a micro-pore area of 1.871 m2/g. The cellulose nanocrystals were synthesized from the extracted cellulose using deep eutectic solvents (DES), choline chloride and lactic acid (1:2 ratio). The cellulose nanocrystals (CNC) synthesized from DES-based exhibited zeta potential and particle size of −16.7 mV and 576.3 d.nm. DES-synthesized cellulose nanocrystals were spherical-like shapes, as observed from TEM images. The present results exposed that formic acid is an effective and green catalyst for the extraction of cellulose and DES for the sustainable synthesis of CNC.

A green extraction technology of lignocellulose from cassava residue by mechanical activation-assisted ternary deep eutectic solvent

Lignocellulose (LC) is a natural polymer material that holds immense potential for various applications. However, extracting LC from biomass wastes with high-starch content has been challenging due to low selectivity and yield. In this study, LC was prepared from cassava residue (CR) via a combination of mechanical activation pretreatment and a citric acid (CA)-enhanced ternary deep eutectic solvent (TDES) consisting of choline chloride (ChCl), lactic acid (LA), and CA. The mechanical activation reduces the size of CR, greatly promoting the removal ability for starch, lignin and hemicellulose using TDES, and thus improving yield and selectivity of LC through this method. The CA esterified LC to prevent its excessive hydrolysis and increased a significantly higher LC content (82.52 wt%) compared to mechanical activation only and DES without CA, increasing by 6.97 times and 1.26 times, respectively. The extraction temperature significantly affected the structure, composition, thermal stability of LC and the properties of recovered TDES. The LC extracted at 90 °C (LC-90) had the highest cellulose content (82.52 wt%), crystallinity index (44.82 %), and higher degradation temperature (339.7 °C). The properties of the recovered TDES and extraction mechanism were analyzed. This study provides a strategy for the high-value utilization of biomass waste.

Physico-Thermal and Mechanical Characterization of Alfa Fiber/Polypropylene Composites: Effects of Fiber Treatment and MAPP Compatibilization

ABSTRACT This study investigates the enhancement of compatibility between natural reinforcement materials and polymer matrices, with a focus on Alfa fibers polypropylene (PP) composites. Composites Alfa fibers/PP are prepared using untreated and treated alfa fibers and with or without the addition of a MAPP compatibilizing agent. Firstly, Alfa fibers extracted from the plant are categorized into two groups: untreated and treated with a 3% (wt/v) alkaline solution followed by bleaching. This chemical treatment significantly increases the cellulose content and crystallinity index of the fibers, with improvements of 39.7% and 13.6%, respectively. Secondly, the study incorporates 5 wt% MAPP in the PP matrix as a compatibilizer. The composites produced with 30 wt% of alfa fibers are processed using a single screw extruder, followed by injection molding. Composites samples obtained are characterized using various methods. Thermal analysis reveals that the incorporation of chemically treated alfa fibers along with MAPP significantly accelerates the crystallization rate of the PP matrix, indicating the fibers’ role as effective nucleating agents. Mechanical testing shows marked improvements in the Young’s modulus and tensile strength of the composites obtained with treated alfa fibers reinforcing the MAPP-PP matrix, with increases of 1.67% and 4.61% over their untreated counterparts, respectively.

Enhanced Cellulose Extraction from Banana Pseudostem Waste: A Comparative Analysis Using Chemical Methods Assisted by Conventional and Focused Ultrasound

This study investigates the effectiveness of various chemical methods, both ultrasound-assisted and non-assisted, for extracting cellulose from banana pseudostem (BPS) waste, comparing the results with commercial pine and eucalyptus cellulose fibers. Delignification treatments with NaOH (25% and 30%) and H2O2 (8%) were evaluated, applied with both conventional and focused sonication. Ultrasound-assisted methods, particularly with NaOH, achieved cellulose percentages as high as 99.5%. X-ray diffraction (XRD) analysis revealed that NaOH treatments significantly increased the cellulose crystallinity index, reaching up to 67.9%, surpassing commercial fibers. Scanning electron microscopy (SEM) results showed that NaOH treatments, especially at 30%, improved fiber morphology and exposure. Thermogravimetric analysis (TGA) indicated that methods using NaOH and focused sonication enhanced the thermal stability of the cellulose. Compared to commercial fibers, some samples obtained with the proposed methods demonstrated higher purity, yield, and thermal stability, highlighting the effectiveness of ultrasound-assisted and NaOH methods.

The Impact of a Non-Pathogenic Strain of Fusarium Oxysporum on Structural and Biochemical Properties of Flax Suspension Cultures.

Flax (Linum usitatissimum L.) is an important crop plant with pharmaceutical significance. It is described in pharmacopoeias (the United States Pharmacopeia and the European Pharmacopoeia), which confirms that it (especially the seeds) is a valuable medicinal product. Similar to flax seeds, which accumulate bioactive compounds, flax in vitro cultures are also a rich source of flavonoids, phenolics, lignans and neolignans. In the present study, flax suspension cultures after treatment of the non-pathogenic Fusarium oxysporum strain Fo47 were established and analyzed. The study examined the suitability of Fo47 as an elicitor in flax suspension cultures and provided interesting data on the impact of these endophytic fungi on plant metabolism and physiology. Two flax cultivars (Bukoz and Nike) and two compositions of media for flax callus liquid cultures were tested. Biochemical analysis revealed enhanced levels of secondary metabolites (total flavonoid and total phenolic content) and photosynthetically active pigments in the flax callus cultures after treatment with the non-pathogenic fungal strain F. oxysporum Fo47 when compared to control, untreated cultures. In cultures with the selected, optimized conditions, FTIR analysis was performed and revealed changes in the structural properties of cell wall polymers after elicitation of cultures with F. oxysporum Fo47. The plant cell wall polymers were more strongly bound, and the crystallinity index (Icr) of cellulose was higher than in control, untreated samples. However, lignin and pectin levels were lower in the flax callus liquid cultures treated with the non-pathogenic strain of Fusarium when compared to the untreated control. The potential application of the non-pathogenic strain of F. oxysporum for enhancing the synthesis of desired secondary metabolites in plant tissue cultures is discussed.

Comparison of kink-band structures and specificities of cell wall polysaccharides in modern and ancient flax fibres

Flax (Linum usitatissimum L.) is a plant of industrial importance, its fibres being presently used for high-value textile applications, composite reinforcements as well as natural actuators. Human interest in this fibre-rich plant dates back several millennia, including to Ancient Egypt where flax was used extensively in various quotidian items. While the recent technical developments of flax fibres continue to diversify through scientific research, the historical use of flax also has rich lessons for today. Through careful examination of ancient Egyptian and modern flax fibres, this study aims to conduct a multi-scale characterization from the yarn to the fibre cell wall scale, linking differences in structure and polysaccharide content to the mechanical performance and durability of flax. Here, a multi-scale biochemical study is enriched by scanning electron microscopy and nanomechanical investigations. A key finding is the similarity of cellulose features, crystallinity index and local mechanical performances between ancient and modern fibres. Biochemically speaking, monosaccharides analysis, deep-UV and NMR investigations demonstrate that ancient fibres exhibit less pectins but a similar hemicellulosic content, especially through uronic acids and galactose, suggesting the sensitivity of these non-crystalline components.

Obtaining Cellulose Fibers from Almond Shell by Combining Subcritical Water Extraction and Bleaching with Hydrogen Peroxide.

Almond shell (AS) represents about 33% of the almond fruit, being a cellulose-rich by-product. The use of greener methods for separating cellulose would contribute to better exploitation of this biomass. Subcritical water extraction (SWE) at 160 and 180 °C has been used as a previous treatment to purify cellulose of AS, followed by a bleaching step with hydrogen peroxide (8%) at pH 12. For comparison purposes, bleaching with sodium chlorite of the extraction residues was also studied. The highest extraction temperature promoted the removal of hemicellulose and the subsequent delignification during the bleaching step. After bleaching with hydrogen peroxide, the AS particles had a cellulose content of 71 and 78%, with crystallinity index of 50 and 62%, respectively, for those treated at 160 and 180 °C. The use of sodium chlorite as bleaching agent improved the cellulose purification and crystallinity index. Nevertheless, cellulose obtained by both bleaching treatments could be useful for different applications. Therefore, SWE represents a promising green technique to improve the bleaching sensitivity of lignocellulosic residues, such as AS, allowing for a great reduction in chemicals in the cellulose purification processes.

Investigating radial gradient variations of nanostructure of cellulose microfibrils in bamboo culm by synchrotron X-ray scattering

Bamboo is a swiftly renewable natural material. A thorough exploration of its functional hierarchical structure is helpful to improve its utilization efficiency. Previous studies have found that there are notable structural distinctions in bamboo fibers and parenchyma cell wall at the nanoscale. The fluctuation in cellulose microfibrils (CMF) within bamboo has been verified as a critical factor significantly impacting the mechanical properties of bamboo fibers. This study systematically examines the radial gradient variation in the cellulose supramolecular structures of bamboo culms through synchrotron X-ray scattering. The measured cellulose crystallinity index (CrI), the diameter and packing distance of CMF, the orientation parameter, and the distribution of microfibril angle (MFA) were found to be correlated with the radial distribution of fibers and parenchyma cells. In the radial direction, the relative CrI values of 004 reflection increased from 26 % for the innermost layer to 51 % for the outermost layer; the CMF diameter decreased from 2.75 nm to 2.66 nm; the packing distance of CMF’ cylinders was reduced from 3.68 nm to 3.35 nm. The measured mean MFA values exhibit a decrease from approximately 70° to around 5°. Moreover, the azimuthal X-ray scattering signals were effectively segregated from fiber and parenchyma cell wall using the non-negative matrix factorisation (NNMF) method. This methodology holds promise for nanostructure analysis in complex plant stems comprising fiber and parenchyma cells, including but not limited to wheat, corn stalks, and other biomaterials.

The effects of the crystallinity index of cellulose on the flexural properties of hybrid-cellulose epoxy composites

This work investigated the effects of the crystallinity index (CI) of cellulose on the flexural properties of hybrid-cellulose epoxy composites. The CI was varied by combining cellulose microfibrils (CMF) and microcrystalline cellulose (MCC), extracted from coir and eucalyptus, respectively, in various mixing ratios. From the XRD analysis, it was shown that the CI values and the CMF/MCC content follow a parabolic-fitting pattern, reaching a maximum value of 82.06% for the CMF/MCC of 30/70. The composites with cellulose of different CI values were fabricated and the flexural properties were measured. The results showed that the flexural strength increased as the CI increased, reaching a maximum of 105.45 MPa for a CI value of 81.87%. However, the flexural modulus displayed a parabolic relationship with respect to the CI value, reaching a maximum of 3,015.53 MPa for a CI value of 81.45%. FTIR spectroscopy was used to study the correlation between the interfacial bonding via hydrogen bonding of hydroxyl groups in cellulose and epoxy, the CI value, and the flexural properties. It was suggested that the strength of the cellulose was an important factor for the flexural strength of the composite, whereas both cellulose strength and interfacial bonding were crucial for the enhancement of the flexural modulus.

Extraction and characterization of microcrystalline cellulose from Vachellia nilotica plant leaves: A biomass waste to wealth approach.

Biobased waste utilization is an intriguing area of research and an ecologically conscious approach. Plant-based materials can be used to render cellulose, which is an eco-friendly material that can be used in numerous aspects. In the current investigation, cellulose was extracted from the leaves of the Vachellia nilotica plant via acid hydrolysis. The application of this research is specifically directed toward the utilization of undesirable plant sources. To validate the extracted cellulose, FT-IR spectroscopy was applied. The cellulose was measured to have a density of 1.234 g/cm3. The crystallinity index (58.93%) and crystallinity size (11.56 nm) of cellulose are evaluated using X-ray diffraction spectroscopy analysis. The highest degradation temperature (320.8°C) was observed using thermogravimetry and differential scanning calorimetry curve analysis. The analysis of particle size was conducted utilizing images captured by scanning electron microscopy. Particle size of less than 30 μm was found and they exhibit non-uniform orientation. Additionally, atomic force microscopy analysis shows an improved average surface roughness (Ra), which increases the possibility of using extracted cellulose as reinforcement in biofilms.

The production of bacterial cellulose from coconut water and its application as a green photocatalyst composite membrane

AbstractIn this research work, bacterial cellulose was produced from the fermentation of coconut water and incubated for 4, 5, and 6 days. The bacterial cellulose membrane was utilized as immobilized silver nanoparticles (AgNPs). A green photocatalyst membrane was prepared by reducing silver ions in the bacterial cellulose matrix structure using local fruit extracts, tomatoes, Citrus hystrix fruit, and mangosteen peel as a reducing agent. The composite was dried in the oven to obtain a more durable fixed structure. The properties of produced bacterial cellulose were determined by measuring the thickness, water retention capacity (WRC), cellulose content, and swelling. The functional group and crystallinity index of bacterial cellulose were observed by FTIR and XRD instrument analysis. The SEM EDX analysis confirms that the silver ions were successfully reduced in the BC matrix, and the UV–Vis spectrum showed that the composite membrane has the ability to degrade the methylene blue solution under sunlight irradiation. The maximum degradation efficiency of the composite membrane against 5 ppm methylene blue solution was achieved by the composite membrane reduced by tomatoes, with a value of 93%. This result proved that the composite membrane produced in this research has excellent capabilities as a green photocatalyst for degrading wastewater containing dye pollutants.

Effect of steam explosion pretreatment on chosen saccharides yield and cellulose structure from fast-growing poplar (Populus deltoides × maximowiczii) wood

The aim of this study was to determine the changes occurring in the wood cellulose of the fast-growing poplar (Populus deltoides × maximowiczii) under the influence of steam explosion (SE) pretreatment. Cellulose from native wood and after pretreatment at 160 and 205 °C was isolated. Cellulose polymerization degree by size exclusion chromatography (SEC) and cellulose crystallinity index by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) were determined. The profiles of sugars in the native wood and in the solid fraction after pretreatment (using the acid hydrolysis method) were also determined. In addition, the profile of monosaccharides in the liquid fraction obtained after steam explosion and in the liquid fraction after acid hydrolysis of the oligosaccharides were investigated using high-performance liquid chromatography (HPLC). This allowed to determine the change in the yield of hexoses and pentoses in the studied material.The behavior of cellulose in wood subjected to steam explosion at 160 and 205 °C and isolated by the Kürschner–Hoffer method was studied by determining the absorption bands of FTIR-ATR spectra. The lateral order index (LOI) of cellulose was calculated from the ratio of the intensity of the corresponding absorption bands A1422/A896 cm−1. Total crystallinity index (TCI) of cellulose was calculated from the ratio of the intensity of absorption bands A1372/A2900 cm−1. TCI of Kürschner-Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C decreased by 5.6 and 5.0%, respectively, with regard to the applied temperature. LOI increased in cellulose isolated from wood subjected to steam explosion at 160 °C (by 0.7%) and at 205 °C (by 19.2%) in relation to the index of cellulose isolated from native wood. Kürschner–Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C exhibited, respectively, a reduced degree of polymerization of about 11% and about 8%. Polydispersity index in Kürschner–Hoffer cellulose was 1% lower after both pretreatments than native sample.

Cellulose Isolation and Characterization of Green Seaweed C. Lentillifera from Halmahera, Indonesia

Caulerpa lentillifera or known as sea grapes is a type of green seaweed which is rich of nutritional components and widespread in the tropical regions in Asia, including Indonesia. Moreover, C. lentillifera contains of polysaccharides, such as cellulose which has the potential to various applications. In this study, C. lentillifera collected from Halmahera, Indonesia was determined for its chemical compositions (moisture, ash, extractives, hemicellulose, α-cellulose contents) and was extracted to obtain cellulose. Isolation of cellulose from C. lentillifera was done by soxhlet extracted using ethanol-benzene solvent to remove extractives, boiling to increase the amount of cellulose extracted, H2O2 bleaching to eliminate any remaining pigments and other contaminants, and freeze drying to get coarse powder of cellulose. The moisture content, ash, extractives, hemicellulose, α-cellulose of C. lentillifera were 11.94%, 31.62%, 11.53%, 35.57%, and 7.95%, respectively. The yield of cellulose obtained was 31.13% based on seaweed dry weight. FE-SEM (Field Emission-Scanning Electron Microscopy) analysis of C. lentillifera showed colonies of diatoms in elliptical shapes. FTIR (Fourier Transform Infrared) measurements indicating cellulose purity after extraction process. X-Ray Diffraction (XRD) analysis resulted some peaks of salt crystals in C. lentillifera and cellulose of C. lentillifera in amorphous form. After extraction, the crystallinity index of cellulose obtained was 37.3%.

Microwaves and Ultrasound as Emerging Techniques for Lignocellulosic Materials

Currently, in the context of biorefinery and bioeconomy, lignocellulosic biomass is increasingly used to produce biofuels, biochemicals and other value-added products. Microwaves and ultrasound are emerging techniques that enable efficient and environmentally sustainable routes in the transformation of lignocellulosic biomass. This review presents some of the most important works published in the last few years on the application of microwaves and/or ultrasound in lignocellulosic materials pretreatment and can be used as a starting point for research into this theme. This review is divided into four parts. In Part I, the theoretical fundamentals of microwave and ultrasound treatments are reviewed. Dielectric constants for biomass, factors that influence pretreatment, are some of the subjects addressed. In Part II, the effects that these techniques have on lignocellulosic biomass (on the size and surface area of the particle; on the content of lignin, hemicellulose and cellulose; on the crystallinity index of cellulose; on the effect of solubilization of organic matter; on hydrolysis and reduction of sugars) are discussed. In Part III, emphasis is given to the contribution of microwaves and ultrasound in obtaining value-added products. In this context, several examples of liquefaction and extraction procedures are presented. Part IV describes examples of performing sonocatalysis on lignocellulosic biomass to obtain value-added products, such as furfural, whose production is significantly reduced by ultrasound treatment.

Extraction and Characterization of Natural Fiber from the Stem of Dombeya Buettneri Plant for Biodegradable Polymeric Composites Application

ABSTRACT The global drive for a circular economy emphasizing sustainability in composite manufacturing processes has been the driving force for current ongoing research studies in natural fibers as sustainable substitutes for non-biodegradable synthetic fibers. The present study was carried out to characterize Dombeya buettneri fiber (DBF) extracted manually from the bark of the plant stem. Determination of physical and mechanical properties, quantitative chemical analysis, Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis and scanning electron microscopy were used to characterize the extracted fiber. Fiber constituents and XRD results showed higher cellulose content (58.45%), crystallinity index (62.32%) and percent crystalline (72.63%). The fiber had a crystallite size of 2.16 nm as determined using the Debye-Scherrer’s equation while FTIR analysis confirmed the presence of various functional groups of lignin, hemicellulose and cellulose on the fiber structure. The results revealed that DBF fiber had a thermal resistance that is up to 229.57°C with a maximum thermal degradation temperature of 356.27°C. Based on the results of this research that are comparable with other studies on cellulosic fiber, DBF fiber has a great potential as an alternative reinforcement for the development of polymer-based bio-composites.

Effects of alkaline‐acid treatment on the physiochemical attributes of natural cellulosic fiber of Arundo donaxL

AbstractIn the present investigation, the cellulose fibers were extracted from Arundo donax through a three‐step treatment. The effects of the alkaline pre‐treatment, acid hydrolysis, and soxhlet‐based extraction on the qualitative and quantitative attributes of the resultant cellulose fibers were investigated. The results of the present study signify a positive correlation between chemical treatment and cellulose content. The overall yield conversion of cellulose was recorded as 156.67%, after Soxhlet‐based purification. It was also observed that the moisture content, percentage of water absorption, rate of water absorption, and ash mass fraction gradually declined after each treatment step. The correlation between the chemical treatment with quantitative and qualitative attributes revealed a gradual increment in cellulose content, crystallinity index, and purity of cellulose fiber extracted from A. donax. The FTIR spectra emphasized that the obtained cellulose was free from impurities after Soxhlet‐based extraction. Simultaneously the DTG curve of A. donax fiber revealed a low rate of derivatization in the fibers extracted after Soxhlet treatment. The SEM and EDX analysis illustrate that the cellulose fibers were devoid of impurities as well as contamination of heavy metal ions.

Integrated application of morphological, anatomical, biochemical and physico-chemical methods to identify superior, lignocellulosic grass feedstocks for bioenergy purposes

Grasses have sufficient potential to be used in the biofuel industry due to many reasons. Hence, systematic assessments of the lignocellulosic biomass obtained from six grasses namely Arundo donax, Chrysopogon zizanioides, Coix lacryma-jobi, Pennisetum purpureum, Saccharum spontaneum, and Sorghum bicolor have been performed to assess their potential for bioethanol production. Selected morphological (height, internode diameter, number of internodes, fresh biomass, dry biomass, total volatile matter), anatomical (vascular bundle, stain intensity), analytical (crystallinity index of cellulose, thermal stability, hemicellulose, moisture content) and biochemical (α-cellulose, acid insoluble lignin) parameters were investigated and statistically analysed to detect the superior grass species. The study indicates that S. spontaneum harbours promising biofuel potential by having high dry biomass (56.33 g), α-cellulose (55.88–67.76%), but lower thermal stability (Tmax: 344.37 °C). Comparable ligno-cellulose properties with respect to dry biomass (54.60 g), α-cellulose content (45.95–64.14%), Tmax (360.51 °C) have been observed for A. donax. However, relatively higher lignin contents (∼17–23%) and crystalline cellulose (43.63%–46.96%) in S. spontaneum and A. donax might have resulted into lesser saccharification yield (216.04–230.08 mg/g). On that aspect, S. bicolor and C. lacryma-jobi might be useful since they possessed lower lignin (14.03–16.56%) and crystalline cellulose (32.51–33.02%) leading to higher glucose yield (263–420.06 mg/g). Taken together, this study indicates that integration of morphological, biochemical, and analytical properties of biomasses are complex, yet useful to predict a ‘superior donor plant’ for bioenergy purposes.

Biotechnological investigation of Pediastrum boryanum and Desmodesmus subspicatus microalgae species for a potential application in bioenergy

The production of photosynthetic microalgae is a promising ecological advantage for obtaining carbon credits. This paper addresses cultivation and preparation, growth analysis, physicochemical characterization (X-ray diffraction-XRD, Fourier transform infrared-FTIR, scanning electron microscopy-SEM, and energy dispersive spectroscopy-EDS), and thermal behavior (thermogravimetry-TG, derivative thermogravimetry-DTG, and differential scanning calorimetry-DSC) of two microalgae, namely Pediastrum boryanum-PB (CH007) and Desmodesmus subspicatus-DS (AEE431E) for a potential application as an energy resource. Regarding the former, the literature reports no specific study on the species, which shows high lipid productivity and fast growth. A synthetic culture medium (Walter culture-WC) was subjected to variations in pH, luminosity, and maximum growth reached in 12 and 13 days for PB and DS, respectively. TG/DTG curves identified the main thermal degradation stages, i.e., dehydration (DS (24.68–158.68 °C) and PB (20.06–116.18 °C)), devolatilization (DS (166.34–543.00 °C) and PB (128.22–493.93 °C)), and gasification or carbonization (DS (>550 °C) and PB (>500 °C)), and DSC curves revealed two endothermic events, an exothermic one for DS, and only one endothermic event and an exothermic one for PB. XRD patterns showed a cellulose crystallinity index (CI) for DS (22.54 %) and PB (28.82 %), confirming the predominance of amorphous regions. SEM images detected external epidermis for DS and some interconnected pores for PB. The FTIR spectra identified functional groups (lipids, proteins, and carbohydrates) and CO, CO, OH, CH, and C-O-C linkages, and EDS and ICP-OES identified the main organic, inorganic, and metallic elements. The microalgae species displayed characteristics similar to those of the other biomasses in the bioenergy industry, enabling their use in thermoconversion processes for biofuel production and considering some socioenvironmental aspects.

Extraction and Characterization of Cellulose and Microcrystalline Cellulose from Teff Straw and Evaluation of the Microcrystalline Cellulose as Tablet Excipient

ABSTRACT Teff (Eragrostis tef), a grass which belongs to the Family Poaceae, is widely cultivated for its starch-rich grains in Ethiopia, generating large amounts of agricultural byproduct, teff straw. The aim of this study was to isolate and characterize cellulose and microcrystalline cellulose (MCC) from teff straw and evaluate MCC as directly compressible tablet excipient. Cellulose was extracted from teff straw and partially depolymerized to obtain MCC. The physicochemical properties of cellulose and MCC powders were characterized. Yields of cellulose and MCC powder from the raw material were 35.2% and 27.2%, respectively. The samples exhibited type-I crystal lattice and similar infrared spectra with that of Avicel PH-101. The degree of polymerization (DP) and crystallinity index of cellulose were 594.51 and 72.26%, respectively. Whereas, MCC powders showed DP of 241.09–257.38 and crystallinity indexes of 76.45–84.52%. Spray dried MCC was found to be more porous and poorly flowable and had higher moisture content when compared with the oven-dried MCC powder. Tablets prepared from both MCC powders fulfil most of the pharmacopoeial requirements. The spray-dried MCC powder also showed superior compactibility to oven-dried MCC. Teff straw can, therefore, be considered to be an alternative source of cellulose and MCC.