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1.
Food Chem ; 335: 127666, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32739821

RESUMO

Proanthocyanidins extracted from Chinese berry leaves (CBLPs) were heated with rice starch in aqueous solution to prepare polyphenols-starch complexes. The physicochemical properties of the complexes were characterized with XRD, DSC, RVA and FT-IR and starch constituents were also analyzed with an enzyme method. Results indicated that the addition of CBLPs destroyed the long ordered structure of rice starch rather than the short ordered structure, since the crystallinity decreased from 21.96% to 18.90% and the ratio of 1047 cm-1/1022 cm-1 showed little difference, consistent with the lower ΔH of complexes with higher CBLPs content. Additionally, the CBLPs-rice starch complexes showed a significantly lower content of rapidly digested starch (RDS, 45.64 ± 3.25%) than that of the native rice starch (67.76 ± 2.15%). These results indicated that CBLPs complexes with rice starch might be a novel way to prepare functional starch with slower digestion.


Assuntos
Lycium/química , Oryza/química , Folhas de Planta/química , Proantocianidinas/química , Amido/química , Varredura Diferencial de Calorimetria , Digestão , Proantocianidinas/isolamento & purificação , Proantocianidinas/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/metabolismo , Amido/farmacocinética , Termogravimetria , Água/química , Difração de Raios X
2.
Bioresour Technol ; 316: 123884, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32889386

RESUMO

Timber industry generates large amounts of residues such as sawdust. Softwoods have a significant economic value for timber production and the Pinus genus is widely utilized. Thus, the aim of this work was to study the hemicellulose extraction and lignin recovery from pine (Pinus spp.) residual sawdust (PRS) by sequential acid-alkaline treatment, generating a cellulose-rich solid fraction. The hemicellulose removed was 87.11% (wt·wt-1) after dilute acid treatment at 130 °C, 4.5% (wt·wt-1) of H2SO4 for 20 min at 120 rpm. Three temperatures were evaluated for recovering the lignin and the highest yield, 93.97% (wt·wt-1), was achieved at 170 °C, 10% (wt·wt-1) of NaOH for 90 min at 120 rpm. Lignin was characterized by Fourier-transform infrared spectroscopy, nuclear magnetic resonance and thermogravimetry. The resulting cellulose-rich fraction exhibited polymorphic transformation. The results demonstrated that PRS is a promising lignocellulosic residue whose lignin and carbohydrates can be readily obtained.


Assuntos
Lignina , Pinus , Celulose , Hidrólise , Termogravimetria , Madeira
3.
Waste Manag ; 116: 131-139, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32799094

RESUMO

Waste tire rubber is produced on a large scale in the automotive industry and is considered difficult to recycle because they have iron, nylon, polyester, and chemical structure formed by cross-links. In this way, the waste is almost always deposited in inappropriate places or incorrectly burned, causing a series of environmental problems. The objective of this work was to analyze the viability of the use of waste tire rubber (5, 10, and 20% m/m) reinforced in polyurethane foam (PU) derived from castor oil to obtain composites, as an alternative for raw materials petrochemical industrial. The materials were characterized by scanning electron microscopy (SEM), optical microscopy (OM), apparent density, contact angle, water absorption, X-ray diffractometry (XRD), spectroscopy infrared (FTIR), thermogravimetry (TGA) techniques, and mechanical tests. The results showed that the residue of the rubber powder reinforced with polyurethane caused an increase in the density of the composites when compared to pure PU, which directly influenced the morphological, physical, thermal, and mechanical properties. This fact occurred because with the insertion of rubber powder in the PU there was a decrease in cell size and increase of pore volume. The TG and DTG analyzes showed that the insertion of the rubber powder improved the thermal stability of the composite when compared to pure PU, as well as impact tests and contact angle.


Assuntos
Óleo de Rícino , Poliuretanos , Reciclagem , Borracha , Termogravimetria
4.
Waste Manag ; 116: 91-99, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32799100

RESUMO

Co-combustion was proposed as an effective and complementary means for the co-treatment of low rank coal semicoke (LRCS) and oil sludge. The combustion, kinetics and gaseous pollutants emission characteristics during co-combustion of LRCS and oil sludge were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). Results showed oil sludge had more complex weight loss characteristics than LRCS. Proper addition of oil sludge could effectively improve the ignition, burnout and comprehensive combustion performance of blends and 60% was a recommended oil sludge blend ratio. High heating rates could also enhance the combustion performance of blends. The activation energy determined by Coats-Redfern method gradually decreased with the increase of oil sludge blend ratio. DAEM kinetic analysis results showed the maximum activation energy of 113.4 kJ/mol was obtained when conversion rate was 0.4 due to the poor ignition performance of LRCS. All of the CO, CO2, NOx and SO2 emission gradually decreased with the increasing oil sludge blend ratio. LRCS had suppression effect on NOx emission during co-combustion while oil sludge was just the opposite. The low sulfur release rate of oil sludge resulted in the decreasing SO2 emission of blends although oil sludge had promotion effect on SO2 emission.


Assuntos
Carvão Mineral/análise , Esgotos , Gases , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
5.
Bioresour Technol ; 317: 124007, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32799076

RESUMO

Microalgae Spirulina has good potential for bio-oil production. Therefore, kinetic and thermodynamic analysis of its pyrolysis process was performed. The activation energy values were estimated using both differential (109-340 kJ/mol) and integral (102-272 kJ/mol) isoconversional methods. Kinetic model was determined using master plot approach and the pyrolysis reaction appeared to transition between nucleation, diffusion and order-based kinetic models. Based on sigmoidal equations, a novel kinetic model equation was proposed which can define the pyrolysis process of algal biomass showing single differential thermogravimetric peak. The proposed kinetic triplet predicted the weight loss evolution quite precisely. Additionally, the thermodynamic feasibility of the reaction was examined based on enthalpy, entropy and Gibbs free energy. It was revealed that heat is consumed to make the raw sample reach a 'more orderly' state until a fractional conversion of 0.35. Moreover, bio-char and the remaining lipids at high temperature impede the reaction spontaneity towards the end.


Assuntos
Pirólise , Biomassa , Cinética , Termodinâmica , Termogravimetria
6.
Free Radic Res ; 54(7): 556-565, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32854555

RESUMO

This study aimed to develop a procedure for preparing a modified silica-naringin hybrid system. To accomplish, the properties of the obtained material were characterized by FT-IR analysis, UV-Vis spectrophotometry, thermogravimetry, scanning electron microscopy (SEM), and zeta potential. 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to characterize and evaluate the antioxidant activity. The naringin release profile at pH = 1.2 and 7.2 were determined. FT-IR studies confirmed the interaction between the naringin and present carrier. The release study indicated that a release an approximately 20% and 50% of the release occurred in the first 30 min in pH = 1.2 and 7.2, respectively. The thermogravimetry and UV-Vis spectrophotometry analysis allowed us to determine the amount of naringin in the studied hybrid material at the level of several percent. The proposed hybrid material shows good stability, as evidenced by the zeta potential of about +30 and -30 mV in an acidic and alkaline environment, respectively. Antioxidant properties are comparable to those of pure naringin. The results suggest that the obtained hybrid material is a promising product with antioxidant properties.


Assuntos
Flavanonas/química , Depuradores de Radicais Livres/química , Dióxido de Silício/química , Antioxidantes/química , Flavanonas/síntese química , Depuradores de Radicais Livres/síntese química , Compostos de Silício/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
7.
Int J Nanomedicine ; 15: 5417-5432, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32801697

RESUMO

Introduction: Green-based materials have been increasingly studied to circumvent off-target cytotoxicity and other side-effects from conventional chemotherapy. Materials and Methods: Here, cellulose fibers (CF) were isolated from rice straw (RS) waste by using an eco-friendly alkali treatment. The CF network served as an anticancer drug carrier for 5-fluorouracil (5-FU). The physicochemical and thermal properties of CF, pure 5-FU drug, and the 5-FU-loaded CF (CF/5-FU) samples were evaluated. The samples were assessed for in vitro cytotoxicity assays using human colorectal cancer (HCT116) and normal (CCD112) cell lines, along with human nasopharyngeal cancer (HONE-1) and normal (NP 460) cell lines after 72-hours of treatment. Results: XRD and FTIR revealed the successful alkali treatment of RS to isolate CF with high purity and crystallinity. Compared to RS, the alkali-treated CF showed an almost fourfold increase in surface area and zeta potential of up to -33.61 mV. SEM images illustrated the CF network with a rod-shaped structure and comprised of ordered aggregated cellulose. TGA results proved that the thermal stability of 5-FU increased within the drug carrier. Based on UV-spectroscopy measurements for 5-FU loading into CF, drug loading encapsulation efficiency was estimated to be 83 ±0.8%. The release media at pH 7.4 and pH 1.2 showed a maximum drug release of 79% and 46%, respectively, over 24 hours. In cytotoxicity assays, CF showed almost no damage, while pure 5-FU killed most of the both normal and cancer cells. Impressively, the drug-loaded sample of CF/5-FU at a 250 µg/mL concentration demonstrated a 58% inhibition against colorectal cancer cells, but only a 23% inhibition against normal colorectal cells. Further, a 62.50 µg/mL concentration of CF/5FU eliminated 71% and 39% of nasopharyngeal carcinoma and normal nasopharyngeal cells, respectively. Discussion: This study, therefore, showed the strong potential anticancer activity of the novel CF/5-FU formulations, warranting their further investigation.


Assuntos
Celulose/química , Portadores de Fármacos/química , Fluoruracila/administração & dosagem , Fluoruracila/farmacologia , Antimetabólitos Antineoplásicos/administração & dosagem , Antimetabólitos Antineoplásicos/farmacologia , Linhagem Celular , Linhagem Celular Tumoral , Neoplasias Colorretais/tratamento farmacológico , Portadores de Fármacos/administração & dosagem , Portadores de Fármacos/farmacocinética , Liberação Controlada de Fármacos , Estabilidade de Medicamentos , Fluoruracila/farmacocinética , Células HCT116 , Humanos , Neoplasias Nasofaríngeas/tratamento farmacológico , Oryza/química , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Difração de Raios X
8.
J Chromatogr A ; 1627: 461393, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823098

RESUMO

The selective extraction and column separation rear earth elements (REEs) were investigated in the present work. Herein, the functional ligand of N, N-dioctyldiglycolic acid (DODGA) was synthesized and chemically grafted on the silica gel (SG) particles to give the novel material SG@DODGA. The obtained SG@DODGA was fully characterized by NMR, BET (Brunauer-Emmett-Teller) N2 physisorption analysis, atom force microscopy (AFM), scanning electronic microscopy (SEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). After investigating the adsorption capability of the SG@DODGA towards 16 kinds of REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc), the results showed that the adsorption kinetic data was better fitted with pseudo-second-order model and Elovich model, the adsorption isotherms data was suitable for Freundlich model. The above result also indicated that the adsorption mechanism between the SG@DODGA and REEs was chemical ion exchange. Moreover, choose SG@DODGA as the column chromatography stationary phase and packed in a glass column for the column studies to obtain breakthroughs profile of each REEs. Furthermore, the column was used to try to separate the mixed 16 kinds of REEs. The first attempt to preliminary separate REEs result showed that this column could be applied for simply separating REEs. The light REEs La, Ce, Pr, Nd exhibited better separation effect than the other REEs.


Assuntos
Glicolatos/química , Metais Terras Raras/isolamento & purificação , Sílica Gel/química , Adsorção , Concentração de Íons de Hidrogênio , Íons , Cinética , Ligantes , Nitrogênio/química , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
9.
J Environ Manage ; 271: 111009, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778293

RESUMO

The fine slag produced from the entrained flow gasifier in coal chemical industry contains a high amount of unburned carbon content, which can reach more than 40%. The coal gasification fine slag is dissipated just by land filling which occupies a lot of land. Consequently, it causes the pollution of soil, water and wastes the combustible carbon in coal gasification fine slag. It is crucial to develop an environmental friendly and economical scheme for the utilization of coal gasification fine slag. To achieve this aim, it is significant to investigate the combustibility of coal gasification fine slag and then propose a comprehensive utilization technology. In this study, the physical and chemical properties of the raw bituminous coal and the produced coal gasification fine slag, including proximate and ultimate analysis, particle size distribution, ash composition, morphology, and specific area were investigated. The combustion and co-combustion characteristics of coal gasification fine slag were analyzed by a thermo-gravimetric analyzer. A drop tube furnace and a fluidized bed reactor were employed to test the combustibility of coal gasification fine slag in a pulverized furnace and a fluidized bed furnace, respectively. Results show that the carbon content in dried coal gasification fine slag is >40% with a heating value > 16 MJ kg-1. Further, thermo-gravimetric analyzer test showed that the combustion property of coal gasification fine slag is worse than that of anthracite and close to that of high ash coal, and there is a non-negligible synergistic effect for raw bituminous coal and coal gasification fine slag co-firing. The combustibility test in drop tube furnace and fluidized bed reactor showed that coal gasification fine slag can be well burned in a pulverized furnace requiring combustion temperature >900 °C and oxygen concentration >10 vol%. However, the fluidized bed furnace was not appropriate for high efficiency coal gasification fine slag burning, because the unburned carbon content of fly ash after coal gasification fine slag combustion is still >14%, even at 900 °C, 21% oxygen concentration and a low fluidization number. It is suggested that coal gasification fine slag will be better to burned it in a pulverized furnace rather than fluidized furnace.


Assuntos
Carbono , Carvão Mineral/análise , Cinza de Carvão , Temperatura , Termogravimetria
10.
J Chromatogr A ; 1627: 461423, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823118

RESUMO

A novel stationary phase co-modified with N-isopropyl acrylamide (NIPAM) and 3-aminophenylboronic acid copolymer on the silica was synthesized through atom transfer radical polymerization (ATRP) reaction for performing mixed-mode and boronate affinity chromatography. The prepared functionalized silica was characterized using Fourier transform infrared spectrometry (FT-IR), elemental analysis (EA) and thermogravimetric analysis (TGA), scanning electron micrographs (SEM) and Brunauer-Emmett-Teller (BET) measurements. The prepared column named Sil-PBA-NIPAM showed great separation performance for hydrophobic, hydrophilic, positional isomer, acidic and alkaline compounds. Besides, the mixture of cis-diol and non-cis-diol compounds was used to prove that the developed column also has potential to capture and enrich cis-diol compounds. The prepared column possesses merits of time-saving, high selectivity to cis-diol compounds and molecular-planarity selectivity compared with two commercial single-mode columns. The theoretical plates of material can reach to 57472 and the column has good hydrolysis stability and batch-to-batch reproducibility. In summary, the prepared column possesses good hydrophilicity, hydrophobicity, molecular-planarity selectivity and boronate affinity abilities for the analysis of various compounds.


Assuntos
Acrilamidas/química , Ácidos Borônicos/química , Cromatografia/métodos , Polímeros/química , Ácido Benzoico/análise , Cromatografia de Fase Reversa , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Fenóis/análise , Polimerização , Reprodutibilidade dos Testes , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
11.
Waste Manag Res ; 38(9): 942-965, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32705957

RESUMO

Thermogravimetric analysis (TGA) is the most widespread thermal analytical technique applied to waste materials. By way of critical review, we establish a theoretical framework for the use of TGA under non-isothermal conditions for compositional analysis of waste-derived fuels from municipal solid waste (MSW) (solid recovered fuel (SRF), or refuse-derived fuel (RDF)). Thermal behaviour of SRF/RDF is described as a complex mixture of several components at multiple levels (including an assembly of prevalent waste items, materials, and chemical compounds); and, operating conditions applied to TGA experiments of SRF/RDF are summarised. SRF/RDF mainly contains cellulose, hemicellulose, lignin, polyethylene, polypropylene, and polyethylene terephthalate. Polyvinyl chloride is also used in simulated samples, for its high chlorine content. We discuss the main limitations for TGA-based compositional analysis of SRF/RDF, due to inherently heterogeneous composition of MSW at multiple levels, overlapping degradation areas, and potential interaction effects among waste components and cross-contamination. Optimal generic TGA settings are highlighted (inert atmosphere and low heating rate (⩽10°C), sufficient temperature range for material degradation (⩾750°C), and representative amount of test portion). There is high potential to develop TGA-based composition identification and wider quality assurance and control methods using advanced thermo-analytical techniques (e.g. TGA with evolved gas analysis), coupled with statistical data analytics.


Assuntos
Resíduos de Alimentos , Eliminação de Resíduos , Incineração , Resíduos Sólidos/análise , Termogravimetria
12.
An Acad Bras Cienc ; 92(2): e20181062, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32638867

RESUMO

The influence of magnesium on roasting vanadium slag was investigated by simulating the roasting process of vanadium by mixing V2O5 and MgO. The calcination products of V2O5 reacted with MgO at different temperatures which were characterized by X-ray diffraction (XRD), Thermogravimetry-differential scanning calorimetry (TG-DSC) and scanning electron microscope (SEM). There were two mass loss intervals, three endothermic peaks and one exothermic peak appearing during the reaction by the integrated thermal analysis as the temperature increased from room temperature to 1273.15 K. The samples of mixed V2O5 and MgO began to melt at 573.15 K and reacted at 773 K, and the shape of the particles changed from block to ovoid or irregular sphere at 773.15 K. With increasing the reaction temperature from 973.15 to 1073.15 K, the intermediate of VO2 was produced, and MgV2O6 was partially decomposed at 1073.15 K. During this process, the particle shape gradually returned to block shape. The conversion rate of vanadium is 99.4% with MgO of 1.65%.


Assuntos
Magnésio/química , Varredura Diferencial de Calorimetria , Minerais , Termogravimetria , Vanádio
13.
Bioresour Technol ; 314: 123689, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32615444

RESUMO

In this work, the characteristic parameters, evolved gases, reaction mechanisms, and ash conversions of the durian shell (DS) combustion were quantified coupling thermogravimetry, mass spectroscopy, Fourier transform infrared spectroscopy, and X-ray fluorescence spectra analyses. The main stage of the DS combustion occurred between 130.2 and 481.9 °C. Its activation energy value estimated by the three model-free methods ranged from 192.82 to 213.24 kJ/mol. The average enthalpy, entropy and Gibbs free energy changes were in the ranges of 177.74-178.47 kJ/mol, 32.00-34.25 J/(mol·K), and 200.79-207.74 kJ/mol, respectively. The third-order (F3) model best described its most likely reaction mechanism. The main evolved gas was CO2, with no SO2 emission. The ash from the DS combustion belonged to K-type ash. 618 °C and 8 K/min were determined as the optimal operation conditions to jointly optimize the multiple targets of the combustion responses.


Assuntos
Bombacaceae , Gases , Cinética , Minerais , Termogravimetria
14.
J Vis Exp ; (161)2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32716389

RESUMO

The analysis of thermal processes associated to the curing of adhesives and the study of mechanical behavior once cured, provide key information to choose the best option for any specific application. The proposed methodology for the curing characterization, based on thermal analysis and rheology, is described through the comparison of three commercial adhesives. The experimental techniques used here are Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Rheology. TGA provides information about the thermal stability and filler content, DSC allows the evaluation of some thermal events associated to the cure reaction and to thermal changes of the cured material when subjected to temperature changes. Rheology complements the information of the thermal transformations from a mechanical point of view. Thus, the curing reaction can be tracked through the elastic modulus (mainly the storage modulus), the phase angle and the gap. In addition, it is also shown that although DSC is of no use to study the curing of moisture curable adhesives, it is a very convenient method to evaluate the low temperature glass transition of amorphous systems.


Assuntos
Adesivos/química , Varredura Diferencial de Calorimetria , Módulo de Elasticidade , Teste de Materiais , Reologia , Termogravimetria
15.
Chemosphere ; 258: 127179, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554002

RESUMO

Hydrophobic membranes for desalination and toxic organic pollutant removal have been fabricated using polyamide - PDMS (polydimethylsiloxane) chemistries in a one-step protocol. The curing of polyamide and PDMS are orthogonal and co-curing both networks imparts hydrophobicity to the thin film composite membranes. The membranes exhibit increased adsorption of pesticides from the feed water along with maintaining excellent salt rejection capability (97% NaCl rejection), thus giving the membranes a multifunctional character. Three toxic pesticides have been used in this study to demonstrate the viability of combining osmosis desalination technology with organic matter adsorption. The membranes also show excellent resistance to fouling by toxic pesticides (85% salt rejection vs 67% for commercial membranes in the presence of pesticides) and significantly improved chlorine tolerance (93.8% salt rejection vs 86.5% for commercial membranes after 20 h of exposure to sodium hypochlorite solution).


Assuntos
Cloro/química , Dimetilpolisiloxanos/química , Membranas Artificiais , Praguicidas/isolamento & purificação , Purificação da Água/instrumentação , Varredura Diferencial de Calorimetria , Interações Hidrofóbicas e Hidrofílicas , Nylons/química , Osmose , Espectrometria por Raios X , Termogravimetria , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
16.
Waste Manag ; 113: 51-61, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32505975

RESUMO

Much attention has been devoted to disposing traditional-sized poly(methyl methacrylate) (PMMA) waste by pyrolysis for methyl methacrylate (MMA). The pyrolysis of micron-sized PMMA waste, which may be different from that of traditional-sized PMMA waste, received little concern. The present study investigated the kinetics and volatile products of micron-sized PMMA waste pyrolysis in inert atmosphere using thermogravimetry and Fourier transform infrared analysis. A global optimization algorithm namely Shuffled Complex Evolution (SCE) was employed to simultaneously optimize the kinetic parameters. Results indicated that one shoulder and one peak occurred in the MLR variations with temperature. The values of the MLR at the shoulder and peak, the average MLR all increased with the heating rate. The optimized kinetic parameters by SCE can be utilized to well reproduce the experimental thermogravimetric data. The values of activation energy and natural logarithm of pre-exponential factor were in the range of 235.95-248.61 kJ/mol and 16.96-28.76 min-1, respectively. The value of activation energy of micron-sized PMMA waste pyrolysis under the present study was greater than that of the traditional-sized PMMA pyrolysis in the previous studies. MMA and CO2 were the major volatile products generated from the micron-sized PMMA waste pyrolysis. The volatile products yield at peak was much larger than that at shoulder. The MMA and CO2 yield were in the range of 87.98-93.54% and 6.46-12.02%, respectively. High MMA yield may be obtained from the pyrolysis of micron-sized PMMA waste in inert atmosphere by appropriately increasing the heating rate adopted in the reactors in the practical applications.


Assuntos
Polimetil Metacrilato , Pirólise , Análise de Fourier , Cinética , Termogravimetria
17.
Bioresour Technol ; 314: 123699, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32599526

RESUMO

In this study, pyrolysis kinetics and thermodynamic parameters of Safflower residues (SR) obtained from oil extraction were investigated by using TG/DSC-FTIR and py-GC/MS. Thermal analysis was performed from ambient temperature to 750 °C under a nitrogen atmosphere. The first-order reaction kinetics model was applied to thermal analysis data to determine apparent kinetic parameters. Activation energy and pre-exponential factor were calculated as 76.60 kJ.mol-1 and 1.89x106 min-1, respectively. The thermodynamic parameters such as the change in Gibb's free energy, the difference in enthalpy and the entropy change were calculated to be 201.36 kJ mol-1, 71.79 kJ mol-1, and -0.196 kJ mol-1, respectively. TG/FTIR analysis revealed that CO2, C6H5OH, and CC functional group as the main pyrolysis gas products. According to Py-GC/MS results of SR, the presence of high energy-containing compounds among the pyrolysis products was proved. All these results show that SR is suitable for pyrolysis to produce biofuel and/or chemicals.


Assuntos
Carthamus tinctorius , Pirólise , Cinética , Sementes , Termodinâmica , Termogravimetria
18.
Food Chem ; 324: 126876, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32361092

RESUMO

The effect and mechanism of wheat bran cellulose (WBC) on the gelling characteristics of soy protein isolate (SPI) were evaluated. It was found that the water holding capacity, gel strength, and viscoelasticity of SPI gel were improved with the increase of WBC concentration. The addition of WBC (0.5-2.0%, w/v) stabilized the moisture phase and induced the construction of the regular and homogenous three-dimensional gel network. The Raman spectroscopy revealed that WBC addition caused a significant reduction in α-helix percentage (28.92-63.08%) (p < 0.05) with a concomitant increase in ß-sheet (16.92-34.37%) (p < 0.05) and ß-turn (8.09-13.54%) (p > 0.05) percentages of the pure SPI gel. Additionally, hydrogen-bonding interaction between SPI and WBC and the enhanced thermal stability were proposed in the composite gels. Overall, WBC is effective in improving the gel properties of SPI, suggesting its potential application as novel gel modifier in the food industry.


Assuntos
Celulose/química , Géis/química , Proteínas de Soja/química , Fibras na Dieta/análise , Géis/metabolismo , Ligação de Hidrogênio , Reologia , Análise Espectral Raman , Termogravimetria , Viscosidade , Água/química
19.
Sci Total Environ ; 728: 138828, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32361111

RESUMO

In this study, the co-pyrolysis characteristics of cow manure (CM) and Meihuajing bituminous coal (MHJ) blends were investigated in detail. The mass loss behavior and gas evolution characteristics of the blends were analyzed online by thermogravimetry-mass spectrometry (TG-MS), and kinetic analysis was performed. The results demonstrate that the addition of CM to the MHJ increases the reactivity of blends, indicating that interaction between the CM and MHJ occurred during co-pyrolysis. For conventional gases, the release order of gases during CM and MHJ blend pyrolysis is H2O, CO2, CO, CH4, H2. For sulfur-containing gases, with increasing proportion of CM, the emissions of H2S, COS, and C4H4S increase and that of SO2 decrease, and the release temperature interval shifts to lower directions. The Coats & Redfern model was used, an increase of activation energy with CM addition was observed. The optimum blending ratio based on the lowest activation energy is CM:MHJ = 1:3 and the activation energy is 41.9 kJ/mol.


Assuntos
Carvão Mineral , Pirólise , Animais , Bovinos , Feminino , Cinética , Esterco , Espectrometria de Massas , Termogravimetria
20.
J Oleo Sci ; 69(6): 649-657, 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32378554

RESUMO

Microwave is an alternative method which can rapidly pyrolyze biomass by thermal treating, and produce clean syngas and bio-oil products. In this research, the wood particles microwave pyrolysis process was proposed for preparing bio-oil and syngas production. The wood particles were first pyrolyzed by microwave reactor in the process, and then the bio-oil products were separated by cyclone separator and multi-phase separator, syngas products were prepared by steam reforming reactor and absorption tower. Kinetics for larch microwave thermogravimetry reactions were proposed and correlated with lab-scale experiments; the microwave pyrolysis process was simulated in Aspen HYSYS, and the results showed that when pyrolysis reaction temperature and microwave power were 900℃ and 2.0 kW respectively, the maximum bio-oil and syngas production can be achieved. The H2/CO and CO2 content in syngas which can be used in chemical processes such as Fischer-Tropsch synthesis, can be controlled by the molar ratio function of steam and pyrolysis gas.


Assuntos
Extração Líquido-Líquido/métodos , Micro-Ondas , Óleos Vegetais/isolamento & purificação , Polifenóis/isolamento & purificação , Pirólise , Madeira/química , Biomassa , Temperatura Alta , Extração Líquido-Líquido/instrumentação , Vapor , Termogravimetria
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