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1.
Physiol Plant ; 176(3): e14368, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38837358

RESUMO

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.


Assuntos
Biomassa , Celulose , Folhas de Planta , Difração de Raios X , Celulose/química , Celulose/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Varredura Diferencial de Calorimetria , Microscopia Eletrônica de Varredura , Microscopia de Força Atômica , Tamanho da Partícula , Hidrólise
2.
Waste Manag ; 183: 143-152, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38754182

RESUMO

In the present study, press mud (PM), a major waste by-product from sugar industries, was subjected to hydrothermal pretreatment (HTP) to create resource recovery opportunities. The HTP process was performed with the PM samples in a laboratory scale high pressure batch reactor (capacity = 0.7 L) at 160 °C and 200 °C temperatures (solids content = 5 % and 30 %). The pretreatment resulted in separation of solid and liquid phases which are termed as solid hydrochar (HC) and process water (PW), respectively. High heating value (HHV) of HC was âˆ¼14-18 MJ kg-1, slightly higher than that of PM (14 MJ kg-1). The thermogravimetric analysis showed about 1.5-1.7 times higher heat release from HC burning compared to that observed from combustion of PM. Apart from this, the HC and PM showed no phytotoxicity during germination of mung bean (Vigna radiata). Moreover, the biochemical methane potential test on the PW showed a generation of 167-245 mL biogas per gram of chemical oxygen demand added. Hence, the HTP offers several resource recovery opportunities from PM which may also reduce the risks of environmental degradation.


Assuntos
Temperatura Alta , Água/química , Resíduos Industriais/análise , Biocombustíveis/análise , Análise da Demanda Biológica de Oxigênio , Termogravimetria
3.
Spectrochim Acta A Mol Biomol Spectrosc ; 316: 124289, 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-38692101

RESUMO

Biphasic calcium phosphate (BCP), consisting of bioceramics such as HAp + ß-TCP and Ca10(PO4)6(OH)2 + Ca3(PO4)2, is a popular choice for optimizing performance due to its superior biological reabsorption and osseointegration. In this study, BCP was produced by calcining the bones of tilapia fish (Oreochromis niloticus) reared in net cages and slaughtered at an age ranging from 15 to 420 days. The bones were cleaned and dried, calcined at 900 °C for 8 h, and then subjected to high-energy grinding for 3 h to produce BCP powders. After the calcination process, the crystalline phase's hydroxyapatite (HAp) and/or beta-tricalcium phosphate (ß-TCP) were present in the composition of the bioceramic. The age-dependent variation in phase composition was confirmed by complementary vibrational spectroscopy techniques, revealing characteristic peaks and bands of the bioceramic. This variation was marked by an increase in HAp phase and a decrease in ß-TCP phase. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) from 25 to 1400 °C showed the characteristic mass losses of the material, with a greater loss observed for younger fish, indicating the complete removal of organic components at temperatures above 600 °C. Comparison of the results obtained by X-Ray Diffraction (XRD) and Rietveld refinement with Raman spectroscopy showed excellent agreement. These results showed that with temperature and environment control and adequate fish feeding, it is possible to achieve the desired amounts of each phase by choosing the ideal age of the fish. This bioceramic enables precise measurement of HAp and ß-TCP concentrations and Ca/P molar ratio, suitable for medical orthopedics and dentistry.


Assuntos
Osso e Ossos , Cerâmica , Análise Espectral Raman , Animais , Cerâmica/química , Osso e Ossos/química , Tilápia/metabolismo , Difração de Raios X , Hidroxiapatitas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fosfatos de Cálcio/química , Termogravimetria
4.
Int J Mol Sci ; 25(10)2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38791139

RESUMO

2,3-dihydro-5,6,7,8-tetranitro-1,4-benzodioxine (TNBD), molecular formula = C8H4N4O10, is a completely nitrated aromatic ring 1,4-benzodioxane derivative. The convenient method of TNBD synthesis was developed (yield = 81%). The detailed structure of this compound was investigated by X-ray crystallography. The results of the thermal analysis (TG) obtained with twice re-crystallized material revealed the onset at 240 °C (partial sublimation started) and melting at 286 °C. The investigated material degraded completely at 290-329 °C. The experimental density of 1.85 g/cm3 of TNBD was determined by X-ray crystallography. The spectral properties of TNBD (NMR, FT-IR and Raman) were explored. The detonation properties of TNBD calculated by the EXPLO 5 code were slightly superior in comparison to standard high-energy material-tetryl (detonation velocity of TNBD-7727 m/s; detonation pressure-278 kbar; and tetryl-7570 m/s and 226.4 kbar at 1.614 g/cm3, or 260 kbar at higher density at 1.71 g/cm3. The obtained preliminary results might suggest TNBD can be a potential thermostable high-energy and -density material (HEDM).


Assuntos
Modelos Moleculares , Cristalografia por Raios X/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Estrutura Molecular , Dioxanos/química , Temperatura , Análise Espectral Raman , Espectroscopia de Ressonância Magnética/métodos , Termogravimetria
5.
J Chromatogr A ; 1727: 464974, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-38761702

RESUMO

Continuous C8 stationary phase gradients are created on commercial Waters Symmetry Shield RP8 columns by strategically cleaving the C8 moieties in a time-dependent fashion. The method relies on the controlled infusion of a trifluoroacetic acid/water/acetonitrile solution through the column to cleave the organic functionality (e.g., C8) from the siloxane framework. The bond cleavage solution is reactive enough to cleave the functional groups, even with polar groups embedded within the stationary phase to protect the silica. Both the longitudinal and radial heterogeneity were evaluated by extruding the silica powder into polyethylene tubing and evaluating the percent carbon content in the different sections using thermogravimetric analysis (TGA). TGA analysis shows the presence of a stationary phase gradient in the longitudinal direction but not in the radial direction. Two different gradient profiles were formed with good reproducibility by modifying the infusion method: one exhibited an 'S'-shaped gradient while the other exhibited a steep exponential-like gradient. The gradients were characterized chromatographically using test mixtures, and the results showed varied retention characteristics and an enhanced ability to resolve nicotine analytes.


Assuntos
Dióxido de Silício , Dióxido de Silício/química , Acetonitrilas/química , Nicotina/análise , Cromatografia Líquida/métodos , Ácido Trifluoracético/química , Termogravimetria , Reprodutibilidade dos Testes , Siloxanas/química , Água/química , Cromatografia Líquida de Alta Pressão/métodos
6.
Luminescence ; 39(5): e4750, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38733198

RESUMO

Ultra-high thermally stable Ca2MgWO6:xSm3+ (x = 0.5, 0.75, 1, 1.25, and 1.5 mol%) double perovskite phosphors were synthesized through solid-state reaction method. Product formation was confirmed by comparing the X-ray diffraction (XRD) patterns of the phosphors with the standard reference file. The structural, morphological, thermal, and optical properties of the prepared phosphor were examined in detail using XRD, Fourier transform infrared spectra, scanning electron microscopy, diffused reflectance spectra, thermogravimetric analysis (TGA), photoluminescence emission, and temperature-dependent PLE (TDPL). It was seen that the phosphor exhibited emission in the reddish region for the near-ultraviolet excitation with moderate Colour Rendering Index values and high colour purity. The optimized phosphor (x = 1.25 mol%) was found to possess a direct optical band gap of 3.31 eV. TGA studies showed the astonishing thermal stability of the optimized phosphor. Additionally, near-zero thermal quenching was seen in TDPL due to elevated phonon-assisted radiative transition. Furthermore, the anti-Stokes and Stokes emission peaks were found to be sensitive toward the temperature change and followed a Boltzmann-type distribution. All these marked properties will make the prepared phosphors a suitable candidate for multifield applications and a fascinating material for further development.


Assuntos
Luminescência , Substâncias Luminescentes , Samário , Temperatura , Compostos de Tungstênio , Compostos de Tungstênio/química , Substâncias Luminescentes/química , Substâncias Luminescentes/síntese química , Samário/química , Medições Luminescentes , Difração de Raios X , Compostos de Cálcio/química , Óxidos/química , Termogravimetria
7.
Sci Rep ; 14(1): 12387, 2024 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-38811644

RESUMO

Chemical processing is among the significant keys to tackle agro-residues utilization field, aiming to obtain value-added materials. Extraction of cellulose nanocrystals (CNCs) is an emerging route to valorize lignocellulosic wastes into high value particles. In this investigation, effect of acidic hydrolysis duration was monitored on size and morphology of obtained crystals; namely: CNCs from Nile roses fibers (NRFs) (Eichhornia crassipes). Different acidic hydrolysis duration range or different characterization techniques set this article apart from relevant literature, including our group research articles. The grinded NRFs were firstly subjected to alkaline and bleaching pretreatments, then acid hydrolysis process was carried out with varied durations ranging from 5 to 30 min. Microcrystalline cellulose (MCC) was used as reference for comparison with NRFs based samples. The extracted CNCs samples were investigated using various techniques such as scanning electron microscopy (SEM), Atomic force microscopy (AFM), Raman spectroscopy, and thermogravimetric (TGA) analysis. The figures gotten from SEM and AFM depicted that NRFs based CNCs appeared as fibril-like shapes, with reduced average size when the NRFs underwent pulping and bleaching processes. This was indicated that the elimination of hemicellulose and lignin components got achieved successfully. This outcome was proven by chemical composition measurements and TGA/DTG curves. On the other hand, AFM-3D images indicated that CNCs topology and surface roughness were mostly affected by increasing hydrolysis durations, besides smooth and homogeneous surfaces were noticed. Moreover, Raman spectra demonstrated that the particle size and crystallinity degree of NRFs based CNCs can be affected by acidic hydrolysis durations and optimum extraction time was found to be 10 min. Thermal stability of extracted CNCs-NRFs and CNCs-MCC was measured by TGA/DTG and the kinetic models were suggested to identify the kinetic parameters of the thermal decomposition of CNCs for each acid hydrolysis duration. Increasing hydrolysis duration promoted thermal stability, particularly for NRFs based CNCs. Results showcased in this article add new perspective to Nile rose nanocellulose and pave down the way to fabricate NRFs based humidity nano-sensors.


Assuntos
Celulose , Eichhornia , Nanopartículas , Celulose/química , Nanopartículas/química , Eichhornia/química , Eichhornia/metabolismo , Hidrólise , Microscopia de Força Atômica , Análise Espectral Raman , Microscopia Eletrônica de Varredura , Termogravimetria , Lignina/química
8.
Int J Biol Macromol ; 270(Pt 1): 132330, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38750840

RESUMO

Developing flame retardant cotton fabrics (CF) is crucial for minimizing the harm caused by fires to people. To improve the flame retardancy of CF, this paper has synthesized a novel flame retardant called diboraspiro tetra phosphonate ammonium salt (N-PDBDN). The structure of N-PDBDN has been analyzed using FT-IR and NMR. Treating CF with N-PDBDN can increase the limiting oxygen index (LOI) to 36.2 % with a weight gain of 10.1 %. Moreover, even after undergoing 50 laundering cycles (LCs), the LOI remains at 27.1 %, indicating good flame retardancy and durability. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) show the presence of P and N elements on N-PDBDN treated CF, suggesting successful bonding between N-PDBDN and cellulose. Thermogravimetric analysis (TGA) results demonstrate that the addition of N-PDBDN significantly enhances the thermal stability and carbon formation ability of CF. Furthermore, cone calorimetry tests reveal reduced heat release rates (HRR), prolonged time to ignition (TTI), and 38 % lower total heat release (THR) in CF treated with N-PDBDN compared with pure cotton. Finally, a potential flame retardant mechanism involving N-PDBDN is proposed. These findings indicate that incorporating an ammonium phosphate group into CF can effectively improve the flame retardancy and durability.


Assuntos
Fibra de Algodão , Retardadores de Chama , Têxteis , Nitrogênio/química , Fósforo/química , Espectroscopia de Infravermelho com Transformada de Fourier , Organofosfonatos/química , Termogravimetria
9.
Int J Biol Macromol ; 270(Pt 1): 132342, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38750851

RESUMO

This study synthesized biocomposites containing starch and WO3 at varying ratios of 10 %, 20 %, 30 %, 40 %, and 50 % and assessed their thermal and radiation-shielding properties. These biocomposites were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD) analysis, particle-size distribution assessments, scanning electron microscopy-energy dispersive X-ray spectroscopy, and thermogravimetric analysis-differential thermogravimetry measurements. Furthermore, the linear attenuation coefficients of the biocomposites were experimentally measured using an NaI(Tl) gamma spectrometry system and theoretically computed using XCOM and GAMOS simulations for comparisons. The XRD and particle-size distribution profiles of the WO3.2H2O powder, respectively, demonstrated evident diffraction peaks and favorable pore-size distributions. Morphological characterizations revealed that the WO3 particles were homogeneously dispersed throughout the starch matrix without any agglomeration. Comparisons of the thermal degradation rates revealed that the pure starch and starch +50%WO3 biocomposite began decomposing at approximately 200°Cand 300 °C, respectively, indicating that increasing WO3 proportions enhanced thermal stability. Furthermore, the starch +50%WO3 biocomposite demonstrated the highest experimental linear attenuation coefficient, with a value of 0.2510 ± 0.0848 cm-1 at a gamma energy of 662 keV. Meanwhile, XCOM and GAMOS simulations revealed theoretical attenuation coefficients of 0.1229 and 0.1213 cm-1 for pure starch and 0.2202 cm-1 and 0.2178 cm-1 for the starch +50%WO3 biocomposite at 662 keV, respectively.


Assuntos
Óxidos , Amido , Tungstênio , Amido/química , Tungstênio/química , Óxidos/química , Fótons , Termogravimetria , Difração de Raios X , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
10.
Int J Biol Macromol ; 269(Pt 2): 132152, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38723811

RESUMO

Carbon nanofibers (CNFs) are very promising materials with application in many fields, such as sensors, filtration systems, and energy storage devices. This study aims to explore the use of eco-friendly biopolymers for CNF production, finding novel, suitable and sustainable precursors and thus prioritising environmentally conscious processes and ecological compatibility. Polymeric nanofibers (PNFs) using cellulose acetate, polylactic acid, and chitosan as precursors were successfully prepared via electrospinning. Rheological testing was performed to determine suitable solution concentrations for the production of PNFs with controlled diameter and appropriate morphology. Their dimensions and structure were found to be significantly influenced by the solution concentration and electrospinning flow rate. Subsequently, the electrospun green nanofibers were subject to stabilisation and carbonisation to convert them into CNFs. Thermal behaviour and chemical/structural changes of the nanofibers during stabilisation were investigated by means of thermogravimetric analysis and Fourier-transform infrared spectroscopy, while the final morphology of the fibers after stabilisation and carbonisation was examined through scanning electron microscopy to determine the optimal stabilisation parameters. The optimal fabrication parameters for cellulose and chitosan-based CNFs with excellent morphology and thermal stability were successfully established, providing valuable insight and methods for the sustainable and environmentally friendly synthesis of these promising materials.


Assuntos
Carbono , Celulose , Quitosana , Nanofibras , Poliésteres , Nanofibras/química , Nanofibras/ultraestrutura , Quitosana/química , Celulose/química , Poliésteres/química , Carbono/química , Química Verde/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
11.
Int J Biol Macromol ; 268(Pt 2): 131984, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38692552

RESUMO

Biomass materials substituting for petroleum-based polymers occupy an important position in achieving sustainable development. Cellulose, a typical biomass material, stands out as the primary choice for producing eco-friendly packaging materials. However, it is still a challenge to efficiently utilize cellulose from waste biomass materials in practice. Herein, cellulose-based films were prepared by pretreating waste corn straw, separating straw husk, straw pith and straw leaf, and extracting cellulose through alkali and sodium chlorite treatment to improve its mechanical properties using the cross-linked polyvinyl alcohol (PVA) method in this work. The prepared composite films were characterized by Fourier transform infrared spectrometer (FTIR), X-ray diffraction instrument (XRD), Scanning electron microscopy (SEM), Thermogravimetric (TG) and mechanical properties. The results indicated that corn straw husk exhibited the highest cellulose content of 31.67 wt%, and obtained husk cellulose had the highest crystallinity of 52.5 %. Compared to corn straw, the crystallinity of husk cellulose, pith cellulose and leaf cellulose increased by 19.5 %, 16.4 % and 44.1 %, respectively. Husk cellulose/PVA composite films were the most thermally stable, with a maximum weight loss temperature of 346.8 °C. In addition, the husk cellulose/PVA composite film had the best tensile strength of 37 MPa. Meanwhile, the composite films had good UV shielding, low water vapor transmission rate and biodegradability. Therefore, this work provides a fine utilization route of waste corn straw, and as-prepared cellulose based films have potential application in eco-friendly packaging materials.


Assuntos
Celulose , Álcool de Polivinil , Zea mays , Zea mays/química , Álcool de Polivinil/química , Celulose/química , Resistência à Tração , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Termogravimetria
12.
Molecules ; 29(10)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38792072

RESUMO

Olmesartan medoxomil (OLM) is a selective angiotensin II receptor antagonist used in the treatment of hypertension. Its therapeutic potential is limited by its poor water solubility, leading to poor bioavailability. Encapsulation of the drug substance by two methylated cyclodextrins, namely randomly methylated ß-cyclodextrin (RM-ß-CD) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TM-ß-CD), was carried out to overcome the limitation related to OLM solubility, which, in turn, is expected to result in an improved biopharmaceutical profile. Supramolecular entities were evaluated by means of thermoanalytical techniques (TG-thermogravimetry; DTG-derivative thermogravimetry), spectroscopic methods including powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier-transform infrared (UATR-FTIR) and UV spectroscopy, saturation solubility studies, and by a theoretical approach using molecular modeling. The phase solubility method reveals an AL-type diagram for both inclusion complexes, indicating a stoichiometry ratio of 1:1. The values of the apparent stability constant indicate the higher stability of the host-guest system OLM/RM-ß-CD. The physicochemical properties of the binary systems are different from those of the parent compounds, emphasizing the formation of inclusion complexes between the drug and CDs when the kneading method was used. The molecular encapsulation of OLM in RM-ß-CD led to an increase in drug solubility, thus the supramolecular adduct can be the subject of further research to design a new pharmaceutical formulation containing OLM, with improved bioavailability.


Assuntos
Olmesartana Medoxomila , Solubilidade , Difração de Raios X , beta-Ciclodextrinas , beta-Ciclodextrinas/química , Olmesartana Medoxomila/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Modelos Moleculares
13.
Int J Mol Sci ; 25(8)2024 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-38673918

RESUMO

Non-degradable plastics of petrochemical origin are a contemporary problem of society. Due to the large amount of plastic waste, there are problems with their disposal or storage, where the most common types of plastic waste are disposable tableware, bags, packaging, bottles, and containers, and not all of them can be recycled. Due to growing ecological awareness, interest in the topics of biodegradable materials suitable for disposable items has begun to reduce the consumption of non-degradable plastics. An example of such materials are biodegradable biopolymers and their derivatives, which can be used to create the so-called bioplastics and biopolymer blends. In this article, gelatine blends modified with polysaccharides (e.g., agarose or carrageenan) were created and tested in order to obtain a stable biopolymer coating. Various techniques were used to characterize the resulting bioplastics, including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC), contact angle measurements, and surface energy characterization. The influence of thermal and microbiological degradation on the properties of the blends was also investigated. From the analysis, it can be observed that the addition of agarose increased the hardness of the mixture by 27% compared to the control sample without the addition of polysaccharides. In addition, there was an increase in the surface energy (24%), softening point (15%), and glass transition temperature (14%) compared to the control sample. The addition of starch to the gelatine matrix increased the softening point by 15% and the glass transition temperature by 6%. After aging, both compounds showed an increase in hardness of 26% and a decrease in tensile strength of 60%. This offers an opportunity as application materials in the form of biopolymer coatings, dietary supplements, skin care products, short-term and single-contact decorative elements, food, medical, floriculture, and decorative industries.


Assuntos
Gelatina , Polissacarídeos , Gelatina/química , Polissacarídeos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Plásticos/química , Biopolímeros/química , Carragenina/química , Varredura Diferencial de Calorimetria , Sefarose/química , Plásticos Biodegradáveis/química
14.
Waste Manag ; 181: 101-113, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38603994

RESUMO

Significant quantities of Posidonia oceanica deposit on some beaches and coastlines every year, which generates high costs associated with the disposal of this waste. Pyrolysis may be an adequate way for its valorization. However, it would imply to know how the process takes place and if the removal of its natural detrital inorganic matter (epiphytes, marine salt and sand) is necessary, which are the objectives of this research. Pyrolysis by thermogravimetry-mass spectrometry was carried out on both the washed and unwashed samples. During this waste pyrolysis, the following occurs: (i) the high alkali metal chloride content promotes fragmentation reactions of carbohydrates and O formation, which increases HCOOH intensities at temperatures between 250 and 360 °C; (ii) from 500 °C to 650 °C, Fe2O3 and decomposition of carbonates seem to be involved in reactions that produce O release and steam and CO2 reforming of hydrocarbons and oxygenated organic compounds with H2 generation; (iii) from 650 °C to 750 °C, Fe2O3, high alkali metal content and carbonate decomposition generate char gasification, an increase in O release, SO2 capture and HCOOH formation. In general, the abundance of inorganic matter (chlorides, carbonates, etc.) minimizes the release of various compounds during pyrolysis, including SO2 and HCl, while increasing HCOOH production. Thus, this high content of inorganic matter may represent an advantage for its pyrolysis, producing value-added chemical products with a reduced environmental impact. Therefore, this study may be the starting point for defining the optimal pyrolysis conditions for this waste valorisation.


Assuntos
Alismatales , Pirólise , Dióxido de Enxofre , Alismatales/química , Dióxido de Enxofre/química , Ácido Clorídrico/química , Termogravimetria , Oxigênio/química
15.
Int J Biol Macromol ; 267(Pt 2): 131367, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38583837

RESUMO

Chitosan (CS)-based bio-nanocomposite food packaging films were prepared via solvent-casting method by incorporating a unique combination of additives and fillers, including polyvinyl alcohol (PVA), glycerol, Tween 80, castor oil (CO), and nano titanium dioxide (TiO2) in various proportions to enhance film properties. For a comprehensive analysis of the synthesized films, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile testing, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and UV-vis spectrophotometry were employed. Furthermore, the antimicrobial efficacy of the films against S. aureus, E. coli, and A. niger was examined to assess their potential to preserve food from foodborne pathogens. The results claimed that the inclusion of castor oil and TiO2 nanoparticles considerably improved antimicrobial properties, UV-vis light barrier properties, thermal stability, optical transparency, and mechanical strength of the films, while reducing their water solubility, moisture content, water vapor and oxygen permeability. Based on the overall analysis, CS/PVA/CO/TiO2-0.3 film can be selected as the optimal one for practical applications. Furthermore, the practical application of the optimum film was evaluated using white bread as a model food product. The modified film successfully extended the shelf life of bread to 10 days, surpassing the performance of commercial LDPE packaging (6 days), and showed promising attributes for applications in the food packaging sector. These films exhibit superior antimicrobial properties, improved mechanical strength, and extended shelf life for food products, marking a sustainable and efficient alternative to conventional plastic packaging in both scientific research and industrial applications.


Assuntos
Pão , Quitosana , Embalagem de Alimentos , Nanocompostos , Titânio , Titânio/química , Quitosana/química , Nanocompostos/química , Embalagem de Alimentos/métodos , Pão/análise , Nanopartículas/química , Conservação de Alimentos/métodos , Permeabilidade , Termogravimetria , Resistência à Tração , Antibacterianos/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Difração de Raios X
16.
Int J Biol Macromol ; 267(Pt 2): 131441, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38583848

RESUMO

The thermal stability of polyurethanes, known for its limitations, was addressed in this research by seeking improvement through the introduction of carbohydrate-based chain extenders. In this research paper, we systematically sought to improve the thermal resistance of polyurethanes by incorporating carboxymethyl cellulose and chitosan, representing a pioneering application of the mixture design approach in their preparation. In this synthesis, hydroxyl-terminated polybutadiene and isophorone diisocyanate (IPDI) were reacted to prepare -NCO terminated prepolymer, which was subsequently reacted with varying mole ratios of CMC and CSN to develop a series of five PU samples. The prepared PU samples were characterized using the Fourier-transformed infrared spectroscopic technique. Thermal pyrolysis of PU samples was examined using thermal gravimetric analysis (TGA). It was observed that, among all the samples, PUS-3 showed remarkable thermal stability over a wide temperature range. A comprehensive statistical analysis was conducted to substantiate the experimental findings. It was estimated that CMC and CSN significantly enhance the thermal stability of the samples when involved in an interaction fashion. The ANOVA Table for the mixture design demonstrates that over 90 % of the total variation in thermal stability is explained by the mixture model across a wide temperature range. Moreover, PSU-3 exhibited 4 % more thermal stability over a wide range of temperatures on average, as compared to contemporary samples.


Assuntos
Carboximetilcelulose Sódica , Quitosana , Poliuretanos , Quitosana/química , Carboximetilcelulose Sódica/química , Poliuretanos/química , Temperatura , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
17.
Int J Biol Macromol ; 267(Pt 1): 131540, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38608992

RESUMO

Lignin-containing nanocellulose (LNC) is a compelling alternative to traditional nanocellulose (NC), it offers enhanced yields and a reduction in the demand for toxic chemicals. This research involves the isolation of LNC from date palm waste using a green hydrolysis process and its subsequent characterization. The potential of using ionic liquids (ILs) as green solvents to isolate LNC has not yet been explored. Our findings suggest that 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) can hydrolyze partially delignified and unbleached lignocellulose, achieving LNC synthesis. The obtained LNC showed a higher yield than its NC counterpart and exhibited rod-shaped fibers with nanoscale diameters and micrometer lengths, indicating a high aspect ratio. Dynamic Light Scattering (DLS) results indicate average particle sizes of 143.20 nm for NC and 282.30 nm for LNC, with a narrow particle size distribution conforming their monodisperse behavior. Thermogravimetric analysis and differential scanning calorimetry revealed high thermal stability (initial degradation temperature = 222.50 °C and glass transition temperature = 84.45°C) of LNC. Moreover, the obtained LNC fibers were crystalline (crystallinity index = 52.76 %). Their activation energy (124.95 kJ/mol) was determined using the Coats-Redfern method by employing eight solid-state diffusion models. Overall, this study motivates the use of ILs as green solvents to produce lignocellulose derivatives that are suitable for various applications.


Assuntos
Celulose , Química Verde , Lignina , Phoeniceae , Solventes , Lignina/química , Solventes/química , Celulose/química , Química Verde/métodos , Phoeniceae/química , Hidrólise , Líquidos Iônicos/química , Termogravimetria , Resíduos , Temperatura , Tamanho da Partícula
18.
Int J Biol Macromol ; 269(Pt 2): 131894, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38677674

RESUMO

N-methyl-morpholine-N-oxide (NMMO) was initially created as a plasticizer for starch to produce thermoplastic wheat starch. Subsequently, talc powder was used as a reinforcing filler to enhance the mechanical strength of thermoplastic biomass-based composite plastics. The chemical structure, crystal structure, and microscopic morphology were analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Additionally, the thermal properties were explored through thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The hydrated NMMO plasticizer demonstrated an outstanding plasticizing effect on starch, resulting in a composite with remarkable mechanical properties. In fact, the pure thermoplastic wheat starch plasticized with hydrated NMMO exhibited the highest mechanical strength recorded so far, with a tensile strength of up to 9.4 MPa. In addition, talcum powder displayed a noticeable reinforcing effect. When the talcum powder content reached 30 wt%, the targeted composite achieved a tensile strength of 20.5 MPa and a Young's modulus of 177.9 MPa. These values were 118 % and 48 % higher, respectively, than those of the pure thermoplastic starch sample. This innovative plasticizing method opens up a new avenue for the development of high-mechanical-strength thermoplastic biomass-based composite plastics with promising potential applications.


Assuntos
Biomassa , Plastificantes , Plásticos , Amido , Talco , Resistência à Tração , Triticum , Amido/química , Talco/química , Triticum/química , Plásticos/química , Plastificantes/química , Pós , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Fenômenos Mecânicos , Difração de Raios X
19.
J Environ Manage ; 357: 120835, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38581897

RESUMO

Euphorbia Rigida (E. Rigida), a lignocellulosic biomass with low ash content, is a suitable feedstock for pyrolysis. This work investigated the physicochemical characteristics and thermokinetic analysis of E. Rigida pyrolysis by using isoconversional and master plots methods. Ultimate and proximate analyses and oxygen bomb calorimeter were used to determine the physicochemical parameters. The activation energies were calculated using model-free methods (KAS, Friedman and Starink) and were found as 184, 178 and 185 kJ/mol, respectively. Using Fraser-Suzuki deconvolution, pseudo-components were also calculated and the active pyrolysis region was divided into three zones. The master plots showed that reaction order mechanisms (Fn) were effective in Zone I, and diffusion mechanisms (Dn) were well matched in Zone II and Zone III. The thermodynamic parameters (ΔH, ΔG and ΔS) were calculated and according to these results, E. Rigida pyrolysis was an endothermic and non-spontaneous process.


Assuntos
Euphorbia , Pirólise , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Termodinâmica , Cinética , Biomassa
20.
Mar Pollut Bull ; 202: 116361, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38636345

RESUMO

A variety of machine learning (ML) models have been extensively utilized in predicting biomass pyrolysis owing to their prowess in deciphering complex non-linear relationships between inputs and outputs, but there is still a lack of consensus on the optimal methods. This study elaborates on the development, optimization, and evaluation of three ML methodologies, namely, artificial neural networks, random forest (RF), and support vector machines, aimed to determine the optimal model for accurate prediction of biomass pyrolysis behavior using thermogravimetric data. This work assesses the utility of thermal data derived from these models in the computation of kinetic and thermodynamic parameters, alongside an analysis of their statistical performance. Eventually, the RF model exhibits superior physical interpretability and the least discrepancy in predicting kinetic and thermodynamic parameters. Furthermore, a feature importance analysis conducted within the RF model framework quantitatively reveals that temperature and heating rate account for 98.5 % and 1.5 %, respectively.


Assuntos
Biomassa , Aprendizado de Máquina , Redes Neurais de Computação , Pirólise , Termogravimetria , Máquina de Vetores de Suporte , Termodinâmica
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