Crystallinity Index Research Articles

Influence of the extraction method on the chemical, physical and mechanical characteristics of oil palm (Elaeis guineensis) petiole fibers for the reinforcement of composite materials

For their use in polymer and composite materials engineering, and with a view to sustainable development, a great deal of work has been carried out with the aim of describing the properties of plant fibers. This work presents the effects of the extraction method on the chemical, physical and mechanical properties of oil palm petiole fibers (OPPF). To this end, the FPPH to be analyzed were obtained by water retting and chemical retting with soda (5% solution). Their physico-chemical and mechanical characteristics were then studied and compared. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of the main components of lignocellulosic fiber (lignin, cellulose and hemicellulose). Lignin was reduced by 22.74%, hemicellulose by 27.33% and cellulose by 16.87% compared to water retting. XRD revealed a crystallinity index of 58.66% for fibers extracted with a 5% sodium solution and 58.51% for fibers extracted with water retting. Soda retting reduces density by 3%. Tensile tests revealed an average tensile strength of 156.082 MPa for water-rubbed fibers and 205.875 MPa for soda-rubbed fibers, Young’s modulus of 3.432 GPa for water-rubbed fibers and 5.346 GPa for soda-rubbed fibers. Elongation at break for FPPH extracted by water retting was 5.178% and 4.41% respectively. This shows that the extraction method affects mechanical properties (flexibility and stiffness) and should be chosen according to the desired characteristic.

Microfibril Angles and Crystalline Properties of Reaction Woods in Agathis and Sumatran Pine Woods

The microfibril angles (MFAs), relative crystallinity index (RC), and crystallite width (CrW) of compression wood (CPW), lateral wood (LTW), and opposite wood (OPW) in Agathis (Agathis loranthifolia) and Sumatran Pine (Pinus merkusii) stem wood were observed and compared to obtain valuable information on wood quality for effective utilization. The iodine staining method and optical microscopy were applied to measure the MFA in the tangential section. RC and CrW were analyzed with an X-ray diffraction technique. CPW had the largest MFA and the smallest RC in both species. In Agathis, LTW and OPW had comparable MFA, RC, and CrW, whereas the CrW of CPW was the smallest. In Sumatran pine, there was a significant difference in MFA and RC between LTW and OPW. CPW, LTW, and OPW showed comparable CrW. The MFA decreased and RC increased from near the pith to bark in both species. The CrW increased from near the pith to the bark of Sumatran pine, whereas it was constant in Agathis. In conclusion, MFA and RC could be used to identify CPW, LTW, and OPW in both species. There were distinctive MFA and RC properties between reaction wood in both species. Keywords: Agathis loranthifolia, crystalline properties, microfibril angles, Pinus merkusii, reaction wood

Anaerobic digestion of an invasive aquatic plant Ludwigia grandiflora by thermal hydrolysis pretreatment: Correlations between methane kinetics and substrate composition

Ludwigia grandiflora, an emerging aquatic weed, has become a global waterway invader, causing various environmental issues. Anaerobic digestion (AD) of lignocellulosic biomass is a cost-effective treatment method. To enhance methane yield, pretreatment is required to break the rigid lignocellulose structure, which hampers the biodegradability of the biomass. Therefore, in this study, we examined the impact of thermal hydrolysis (TH) pretreatment on L. grandiflora through batch AD tests at temperatures ranging from 150 to 210 °C, with durations of 10 and 30 mins. At 180 °C for 30 mins (severity factor of 3.8), methane yield increased significantly by 142.7 % compared to the untreated condition. Significant methane production differences were observed at temperatures equal to or above 165 °C. Longer retention times, such as 30 mins, were crucial for enhancing methane yield. Additionally, the Modified Gompertz model was a good fit for the AD process, with R2 values ranging from 0.996 to 0.935 and lag phase reduction from 0.273 (untreated) to 0.102-0.000 days for the pretreated conditions. Methane yield and production rates increased from 88.85 mL g-VS−1 and 15.01 mL g-VS−1 day−1 (untreated) to 110.48-206.41 mL g-VS−1 and 30.76-71.33 mL g-VS−1 day−1, respectively. Pearson correlation revealed a positive correlation between cellulose and methane yield enhancement, while lignin, crystallinity index, and pH showed negative correlations. Despite these negative correlations, their impact on the AD process was limited. Overall, changes in lignocellulosic structure and increased cellulose content were the main factors enhancing methane production. Additionally, the study recommends a new cost-effective reactor design for TH pretreatment.

Morphological, chemical, thermal and mechanical analysis of doum fibers as potential reinforcement of polymer composites

The research article addresses, a novel natural cellulosic fiber namely Doum Palm Leaf Stalk Fibers (DPLSF) were extracted from Doum palm tree ( Chamaerops humilis L.) are rich in cellulose, relatively inexpensive, and readily available in Algeria. The characteristic analysis on morphological, physiochemical, thermal and mechanical proprieties of the extracted raw and treated DPLSF with 20% sodium bicarbonate at various times of treatment were exanimated by optical microscope and scanning electron microscopy (SEM), X-ray diffraction method (XRD), Fourier transform infrared (FTIR) spectroscopy, thermos gravimetric analysis (TGA/DTG), differential scanning calorimetry (DSC). The SEM micrographs of the longitudinal topographic surface of the DPLSF after chemical treatment with sodium bicarbonate at various times treatment indicated that the removed the waxy layer and impurities from surface and formed a roughened surface. XRD analysis further confirmed the treatment’s positive effect on the fibers, with the crystallinity index increasing from 71.43% to 81.03%. However, FTIR analysis showed minimal changes in the peak position and intensity of transmittance. The TGA/DTG results revealed a significant mass loss in treated DPLSF, while thermal stability improved from 290°C to 330°C. Additionally, we analyzed the mechanical tensile properties of the treated fibers and observed that fibers treated at 20% NaHCO3 for 24 h exhibited the highest Young's modulus 8.63 GPa. To validate the experimental findings, we compared individual DPLSF results to a numerical simulation using ABAQUS code. This study underscores the potential of DPLSF as a sustainable and eco-friendly alternative to synthetic fibers, offering immense promise for diverse applications.

Influence of UV exposure time and simulated marine environment on different microplastic degradation.

This study investigated the influence of environmental factors (UV radiation and salinity) in the degradative process of microplastics (MPs). MPs derived from polypropylene (PP), polystyrene (PS), and ethylene-vinyl acetate (EVA) were subjected to accelerated photodegradation while being submerged in distilled water or artificial seawater. Depending on the polymer, changes in surface properties, new functional chemical group formation and oxidative index, and thermal characteristics of samples were observed. After photodegradation experiments, EVA-MPs samples showed an increase in their thermal resistance, besides the changes in their surface. PP-MPs crystallinity index increased upon exposure to UV radiation. PS samples showed a higher carbonyl and hydroxyl index after 30h of UV exposure. The methodology exploited applies to any location in the world and can be comparable once considering the total ultraviolet index (UVI). The saline medium increases the crystallinity index of PP and EVA-MPs samples and intensifies the formation of new carbonyl and hydroxyl bonds in EVA-MPs samples. The results showed that several environmental factors should be considered in interpreting MPs photodegradation.

Maximizing Bioethanol Production from Eucalyptus globulus Using Steam Explosion Pretreatment: A Multifactorial Design and Fermenter Development for High Solid Loads

Steam explosion pretreatment is suitable for bioethanol production from Eucalyptus globulus wood. Multifactorial experiment designs were used to find the optimal temperature and residence time required to obtain the best glucose yield from the enzymatic hydrolysis of pretreated materials. The chemical composition, crystallinity index, morphology and polymerization degree of the pretreated materials were correlated with enzymatic accessibility. Simultaneous saccharification and fermentation (SSF) using a fed-batch strategy was applied to three different laboratory-scale fermenters. The optimization of the pretreatment was obtained at 208 °C and 11 min. However, the enzymatic hydrolysis performance did not show significant differences from the material obtained at 196 °C and 9.5 min, which was determined to be the real optimum, owing to its lower energy requirement. The vertical fermenter with type “G” blades and the horizontal fermenter with helical blades were both highly efficient for reaching ethanol yields close to 90% based on dry wood, and ethanol concentrations close to 9.0% v/v.

Strong exciton-photon coupling in self-hybridized organic–inorganic lead halide perovskite microcavities

Abstract Controlling coherent light–matter interactions in semiconductor microcavities is at the heart of the next-generation solid-state polaritonic devices. Organic–inorganic hybrid perovskites are potential materials for room-temperature polaritonics owing to their high exciton oscillator strengths and large exciton binding energies. Herein, we report on strong exciton-photon coupling in the micro-platelet and micro-ribbon shaped methylammonium lead bromide single crystals. Owing to high crystallinity and large refractive index, the as-grown perovskite microcrystals serve as self-hybridized optical microcavities along different orientations due to their distinct physical dimensionalities. In this regard, the perovskite micro-platelet forms a simple Fabry–Perot microcavity in out-of-plane orientation, while the micro-ribbon functions as a Fabry–Perot type waveguide microcavity within the plane of the perovskite sample. Consequently, excitons in these microcavities strongly interact with their corresponding uncoupled cavity modes, yielding multimode exciton-polaritons with Rabi splitting energies ∼205 and 235 meV for micro-platelet and micro-ribbon geometry, respectively. Furthermore, micro-ribbon geometry displays Young’s double-slit-like interference patterns, which together with the numerical simulation readily reveals the parity and the mode order of the uncoupled cavity modes. Thus, our results not only shed light on strong exciton-photon coupling in various morphologies of methylammonium lead bromide microcrystals but also open an avenue for advanced polaritonic devices.

Impact of ionic liquid's cation alkyl chain length and reaction time on cellulose nanocrystals preparation

Traditional methods to obtain cellulose nanocrystals typically involve mechanical and chemical processes and develop an improved process in terms of efficiency, sustainability, and the quality of CNCs produced are interesting. In this sense, we aimed to prepare cellulose nanocrystals (CNCs) from the hydrolysis of microcrystalline cellulose using protic ionic liquids (PILs), named 3-diethylamino-propylammonium hexanoate ([DEAPA][Hex]), 3-dimethylamino- 1-propylammonium hexanoate ([DMAPA][Hex]), and propylammonium hexanoate ([PA][Hex]) at different reaction times. The PILs demonstrated efficiency in producing cellulose nanocrystals, regardless of the cation size and reaction times. However, as expected the properties of the CNCs varied depending on the studied condition. The highest yield was observed in DMAPA[Hex], with a 34 % conversion. Crystalline indices decreased independent of the cation sizes and reaction times. Thermal stabilities were shifted to higher temperatures up to 92 ºC probably due to PILs cation sizes. In contrast, increasing reaction times decreased nanocrystals’ thermal stabilities up to 51ºC. So, protic ionic liquids (PILs) can be considered more environmentally friendly or sustainable solvents compared to traditional organic solvents for preparing cellulose nanocrystals. In the present work, it is reported an alternative method for obtaining CNCs and additionally provide the best preparation conditions for achieving important properties of this nanomaterial, with the potential for various applications.

Modification of TEMPO-oxidized cellulose nanofibers as a source of potassium and its impact on onion plant

This research study aims to improve the productivity and vegetative growth characteristics of onion to meet local demands and the volume of exports. This was done by the application of foliar nano-fertilizers based on cellulose nanofibers (CNF). TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) -oxidized cellulose nanofibers (TO-CNFs) were fabricated using the TEMPO-oxidized method in the presence of sodium or potassium hydroxide to obtain sodium carboxylate TO-CNFs (N-CNF) and potassium carboxylate TO-CNFs (K-CNF), respectively. Also, potassium acrylate was used in grafting N-CNF to get potassium polyacrylate-g-sodium carboxylate TO-CNFs (G-CNF). The prepared CNFs were described via various techniques such as FTIR, SEM, TGA, and XRD. X-ray analysis demonstrated that N-CNF, K-CNF, and G-CNF consisted of a crystalline domain of crystallinity index 0.45, 0.41, and 0.55, respectively. K-CNF showed marginally lower thermal stability than N-CNF influenced by its crystalline properties. The vegetative growth and the yield of onion plants, plus the content of photosynthetic pigments, minerals, cellulose, hemicellulose, and lignin, as well as total phenols, flavonoids, and indoles, were studied. The results showed that the application of K-CNF as a foliar nano-fertilizer improved the onion yield and the content of elements, protein, total soluble solid, phenols, and indoles as well as the content of cellulose and lignin

Insect residues as an alternative and promising source for the extraction of chitin and chitosan

This work aimed to obtain and characterize chitin and chitosan extracted from the rearing residues of Tenebrio molitor, Zophobas morio, and Blaptica dubia insects in different growth stages in the same rearing cycles chitin and chitosan yielded 11.21 %–20.89 % and 6.26 %–7.07 %, respectively. The deacetylation degrees of chitosan ranged from 75.75 %–89.21 %, and the solubilities from 69.88 %–94.39 %. Infrared spectroscopy corroborated the acquisition of chitin and chitosan and can be used as a semi-quantitative technique for determining the degree of chitosan deacetylation. The X-ray diffraction profiles revealed the presence of α-chitin, and the relative crystalline indices ranged from 65.9 %–89.2 %. Typical TG profiles with two thermal events are observed for chitin and chitosan samples with different residue contents from the extraction procedure. The chitosan solutions exhibited pseudoplastic behavior, with apparent viscosities ranging from 195.96 to 249.86 mPa.s. The characterization results of the biopolymers extracted from insect residues were similar to those obtained from conventional sources. The growth stage influenced the chitin yield and crystallinity index. The results of this study reinforce the feasibility of using alternative sources of chitin and chitosan, providing the use of waste from insect farms and contributing to sustainability and a circular economy.

New fluorescent Schiff base modified nanocellulose-based chemosensors for the selective detection of Fe3+, Zn2+ and Cu2+ in semi-aqueous media and application in seawater sample

Stimulus-responsive fluorescent-modified biopolymers have received significant attention in the field of chemosensors. Herein, four new fluorescent dyes, namely, S1: (PDA-DANC), S2: (SAL-PDA-DANC), S3: (BrSAL-PDA-DANC) and S4: (ClSAL-PDA-DANC) have been successfully synthesized from 2,3-dialdehyde nanocellulose (DANC) for the detection of heavy metals. The microstructural and photophysical properties of nanocellulose (NC), microcrystalline cellulose (DANC) and the synthesized S1 to S4 dyes were investigated by FT-IR, SEM-EDX, XRD, TGA, DLS and photoluminescence. NC, obtained from conversion of MCC, shows an average size of 802.4 nm with 0.141 of polydispersity index (PdI), and a crystalline index (CI) of 82.40 % and crystallite size of 4.68 nm. The synthesized dyes present good fluorescent properties and have been therefore exploited for developing new probes for heavy metal ions detection. Remarkable “turn off” and/or “turn on” behaviors with Fe3+ and Cu2+ and with Zn2+ in DMF/water solution have been demonstrated, allowing the sensitive and selective determination of these heavy metal ions with a low limit of detection (LOD). Finally, the evaluation of the Fe3+ sensing in a real seawater sample was investigated.

Fabrication and Testing of Crop Waste Ceiba pentandra Shell Powder Reinforced Biodegradable Composite Films.

Ceiba pentandra shell powder (CPSP) biowaste is chosen as a biofiller combined with poly(vinyl alcohol) (PVA) as a matrix to make biofilms to increase the exploitation of biowaste materials and reduce the use of plastic materials. FTIR plots indicated no significant chemical reaction or formation of new functional groups during interaction between PVA and CPSP. XRD diffractograms showed that the crystallinity index (35.3, 38.6, 42.3, 46.4, and 48.5%) and crystalline size (18.14, 20.89, 23.23, 24.87, and 26.34 nm) of biofilms increased with CPSP loading (5-25 wt %). The PVA/CPSP films are thermally stable up to 322 °C. The peak highs of AFM images showed that the films' surface roughness gradually increased from 94.75 nm (5 wt % CPSP) to 320.17 nm (25 wt % CPSP). The FESEM micrographs clarify the homogeneous distribution of CPSP in the PVA matrix. Tensile strength and tensile modulus are noticeably increased by 26.32 and 37.92%, respectively, as a result of the loading of CPSP from 5 to 20 wt % in the PVA matrix. The PVA/CPSP films outperform pure PVA films in UV shielding (350-450 nm). The 59% weight loss of films was estimated during 60 days of burial. The fabricated biofilms maintained their suitable structural, thermal, morphological, and mechanical properties. Additionally, they exhibited consistent performance in ultraviolet (UV) barrier, opacity, water absorption, water vapor permeability, soil burial, and antimicrobial characteristics over time. Overall, PVA/CPSP (5-25 wt %) films are biodegradable and have promising applications as good packaging materials.

Effect of Alkali Treatment under Ambient and Heated Conditions on the Physicochemical, Structural, Morphological, and Thermal Properties of Calamus tenuis Cane Fibers

This study explores the effect of alkali treatment at ambient (25 °C) and elevated temperatures (100 °C) on the physicochemical, structural, morphological, and thermal properties of Calamus tenuis cane fibers (CTCFs) for the first time. Our purpose is to investigate their potential use as reinforcement in polymer composites, since cane fibers are generally known for their accurate and consistent geometrical orientation. Treatment with 8% (w/v) sodium hydroxide (NaOH) is carried out at ambient temperature and at 100 °C for 4 h. Chemical analysis and Fourier transform IR spectroscopy (FTIR) indicate some removal of non-cellulosic elements from CTCFs during alkali treatment, resulting in increased surface roughness, as confirmed by using SEM micrographs. This removal of non-cellulosic elements leads to an enhancement in the density of the treated CTCFs. Untreated and treated fibers are analyzed for maximum degradation temperature, thermal stability, and kinetic activation energy (Ea) using thermogravimetric analysis (TGA). In particular, Ea was considerably diminished with treatment and temperature. X-ray diffraction (XRD) results show an improved crystallinity index (37.38% to 44.02%) and crystallite size (2.73 nm to 2.98 nm) for fibers treated with 8% NaOH at ambient temperature. In conclusion, a general benefit was achieved by treating CTCFs, though the influence of increasing temperature treatment appears controversial.

Agro-wastes bioconvertion by an Amazonian isolate of Ganoderma sp. and a commercial strain of Ganoderma lingzhi

Agro-industrial wastes discarded in nature may cause environmental damage; however, they have potential for application in mushroom cultivation, making it possible to bioconvert these wastes into materials of higher added value with the possibility of application in different industrial segments. The aim of this work was to compare the biotransformation potential of Amazon lignocellulosic wastes by Ganoderma sp. (isolated in the Amazon) and G. lingzhi (a commercial strain). The mushrooms were grown in açaí (Euterpe sp.), guaruba-cedro (Vochysia maxima), and three different batches of marupá (Simarouba amara) wastes. Initial substrates (IS) and spent mushroom substrates (SMS) were subjected to physico-chemical analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and crystallinity index (CrI). A trend to decrease moisture, ash, lipids, carbon, and cellulose levels was observed in SMS. It is highlighted that after the growth of G. lingzhi and Ganoderma sp., there was a reduction in lignin by 29% and 48%, respectively, while there was an average increase in nitrogen content of 44% and 142% in SMS, respectively. SEM analysis showed visible loosening of lignocellulose fibers; XRD showed a characteristic peak of amorphous cellulose; and the CrI highlighted the coexistence of ordered and disordered regions. Thus, the mushrooms have shown potential in the bioconversion of Amazon wastes, notably for Ganoderma sp., which has demonstrated high potential for delignification and fortification of waste playing potential for application in the cellulose and animal feed industries.

Effects of pre-drying treatment and particle sizes on physicochemical and structural properties of pumpkin flour

The objective of this study is to investigate the effect of pre-drying treatment and particle size on pumpkin flour's compositional, functional, pasting, thermal, and structural properties. Pre-drying treatment and reducing the size of particles have led to an increase in the levels of crude fiber, phytochemicals, and functional properties. However, the amounts of moisture and lightness of color decreased with pretreatment, but improved with particle size reduction. Among the samples, those that were finely milled after pre-treatment showed the highest viscosities, while the untreated samples that were coarsely milled had lower viscosities. The pre-drying treatments yielded notable reductions in both gelatinization temperature and enthalpy of the flour matrix, in comparison to untreated flours. FTIR analysis has indicated that no new functional groups were produced. XRD analysis suggests that while pre-drying treatment leads to decreases in crystallinity index, fine milling leads to increments. The morphological pattern suggested that pretreatment effectively altered the original surface structure of the flour, but particle size reduction did not.

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.

Exploration of photo-catalytic activity of nano-hydroxyapatite based on the crystallographic parameters: Estimation of crystallite size using X-ray diffraction data

Nano-hydroxyapatite was synthesizedfrom CaCO3and waste eggshells reacting with ortho-phosphoric acid, and titaniumwas doped to enhance the photocatalytic activity. The sample was characterized by X-ray diffraction technique, and different crystallographic parameters were explored focusing on crystallite size, microstrain, crystallinity index, lattice parameter, degree of crystallinity, microstrain, volume fraction of β-TCP, percentage of HAp, percentage of β-TCP, dislocation density, volume of unit cell, etc. To justify nano-crystallite size different models and equations such as the Williamson-Hall plot, linear straight -line model, Monshi-Scherrer model, Sahadat-Scherrer model, etc were employed. The effects of photocatalytic activity of synthesized hydroxyapatites were evaluated by varying the dye concentration, pH, interaction time, catalyst dose, and light source (halogen and sunlight). The photocatalytic activity was evaluated by degrading Congo Red dye and a relation was built between crystallographic parameters and catalysis. An easy degradation mechanism was also proposed for the Congo red dye using hydroxyapatite.

Physicochemical Characterization of Acid-Treated Nanocrystal Cellulose and Amorphous Cellulose from Bamboo Sawdust

ABSTRACT The major by-product of bambooworking (i.e. making items from bamboo) is bamboo sawdust, which is a waste product from bambooworking operations and can cause human health hazards. Specifically, this experimental research investigates the effects of acid treatment methods on the physicochemical characteristics of nanocellulose fibers from bamboo sawdust. The experimental acid treatment methods are sulfuric acid hydrolysis for bamboo fiber nanocrystal cellulose (BBF-NCC) and sulfuric acid dissolution for bamboo fiber amorphous cellulose (BBF-AC). The physicochemical properties of nanocellulose from bamboo sawdust include the crystalline structure, morphology, and colloidal stability. The experimental results indicate that BBF-NCC possesses a higher crystallinity index (89.5%), in comparison with 35.4% for BBF-AC. The BBF-NCC is of rod shape with 10 nm in diameter and 50–100 nm in length, while BBF-AC coalesces into clusters of varying sizes. In addition, BBF-NCC possesses higher colloidal stability than BBF-AC, as indicated by a zeta potential of −30.93 mV for BBF-NCC, compared with −19.73 mV for BBF-AC. Essentially, this research is the first to experimentally convert bamboo sawdust into cellulose nanofibers as an eco-friendly and economically viable solution to the waste problem from the bamboomaking industry. Moreover, BBF-NCC and BBF-AC could potentially be adopted as a reinforcing agent in biocomposites or as a carrying agent in multiple applications.

Extraction of Chitin from Giant Tiger Prawn (Penaeus monodon) Shrimp Shell Using Deep Eutectic Solvents and Citric Acid

Chitin, a natural biomass resource, has shown great promise for a wide range of applications because of its high bioactivity. This study evaluated the effectiveness of deep eutectic solvents (DESs) mixed with citric acid as a method for extracting chitin from the shells of giant tiger prawn shrimps (Penaeus monodon). The purity and physicochemical properties of the extracted chitin were compared with those obtained using the traditional chemical extraction method and commercial chitin. The results showed that the highest chitin purity (99.22%) was achieved when choline chloride-glycerol (ChCl–Gl) was used in a 1:2 molar ratio with a citric acid content of 5% w/v (CG2-5%). Additionally, the extracted chitin had a molecular weight of 3.75 × 105 Da and a crystallinity index of 81.34%, which was slightly higher than that of chitin extracted using the conventional method (3.24 × 105 Da and 73.59%). However, there was no significant difference between chitin extracted by CG2-5% and commercial chitin. This suggests that the structure of the biopolymer remained intact following the CG2-5% extraction process. The α-chitins in tiger prawn shrimp shells, as confirmed by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction Analysis (XRD), are analogous to commercial shrimp chitin. These results, achieved without employing potentially harmful chemicals, demonstrate that CG2-5% can efficiently enhance chitin extraction from diverse raw biomass sources without jeopardizing the polymer's structural stability.

Production and In Situ Modification of Bacterial Cellulose Gels in Raisin Side-Stream Extracts Using Nanostructures Carrying Thyme Oil: Their Physicochemical/Textural Characterization and Use as Antimicrobial Cheese Packaging.

We report the production of BC gels by Komagataeibacter sucrofermentans in synthetic (Hestrin and Schramm; HS) and natural media (raisin finishing side-stream extracts; RFSE), and their in situ modification by natural zeolite (Zt) and activated carbon (AC) nanostructures (NSs) carrying thyme oil (Th). The NS content for optimum BC yield was 0.64 g/L for both Zt-Th (2.56 and 1.47 g BC/L in HS and RFSE, respectively), and AC-Th (1.78 and 0.96 g BC/L in HS and RFSE, respectively). FTIR spectra confirmed the presence of NS and Th in the modified BCs, which, compared to the control, had reduced specific surface area (from 5.7 to 0.2-0.8 m2/g), average pore diameter (from 264 to 165-203 Å), cumulative pore volume (from 0.084 to 0.003-0.01 cm3/g), crystallinity index (CI) (from 72 to 60-70%), and crystallite size (from 78 to 72-76%). These values (except CI and CS), slightly increased after the use of the BC films as antimicrobial coatings on white cheese for 2 months at 4 °C. Tensile properties analysis showed that the addition of NSs resulted in a decrease of elasticity, tensile strength, and elongation at break values. The best results regarding an antimicrobial effect as cheese coating were obtained in the case of the RFSE/AC-Th BC.