Thermogravimetric Analyzer Coupled With Fourier Transform Infrared Spectroscopy Research Articles

Investigation of the decomposition behavior of the fluoroalkyl acrylate homopolymer and its grafted copolymers onto high-density polyethylene

In this study, the thermal degradation behavior of both poly(3,3,4,4,5,5,6,6,7,7,8,8,8-dodecafluoro-5-methyloctyl-4-(acryloyloxy) benzoate), poly(ABCF13) and its graft copolymers onto high-density polyethylene (HDPE) was investigated in detail. The homopolymers and grafted copolymers were synthesized using the bulk-melt polymerization method in the presence of benzoyl peroxide; 10% and 40% of ABCF13 were used in the graft copolymers. The combined analytical technique, Thermo Gravimetric Analysis coupled with Fourier Transform Infrared Spectroscopy (TGA/FTIR), was utilized to understand the obtained products' thermal behavior and formed decomposition chemicals. The thermal tests were carried out in both air and N2 atmospheres. The experimental results showed that the first weight loss of poly(ABCF13) in air and N2 atmospheres started at about 226°C (1.00%), and the primary and early decomposition product was determined as CO2. The weight loss pattern in graft copolymers at lower concentrations closely resembled that of the homopolymer. However, at higher concentrations, the resulting products exhibited a distinct decomposition mechanism characterized by a gradual decrease in trend. This segmented behavior may indicate the coexistence of the homopolymer and grafted copolymers within the matrix. Moreover, the findings showed that the semi-fluorinated grafted unit had a substantial retardation effect on the polymer.

Analytical Pyrolysis of Soluble Bio-Tar from Steam Pretreatment of Bamboo by Using TG-FTIR and Py-GC/MS.

Steam pretreatment at high temperatures enables fresh bamboo to possess antifungal and antiseptic properties. The process produces a large amount of wastewater that urgently needs to be recycled. Soluble bio-tars derived from wastewater under low-temperature (LTS-tar) and high-temperature (HTS-tar) steam pretreatments of moso bamboo were studied with a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas-chromatography/mass spectrometry (Py-GC/MS). Thermogravimetric analysis showed that in the three stages of the thermal decomposition process, the final residue of the bamboo and HTS-tar had two main peaks of 0.88 wt% and 6.85 wt%. The LTS-tar had much more complicated thermal decomposition behavior, with six steps and a high residue yield of 23.86 wt%. A large quantity of CH4 was observed at the maximum mass loss rates of the bamboo and bio-tars. Acids, aldehydes, ketones, esters, and phenolic compounds were found in the pyrolysis products of the bamboo and soluble bio-tars. Both bio-tars contained carbohydrates and lignin fragments, but the LTS-tar under mild steam conditions had more saccharides and was much more sensitive to temperature. The lignin in the bamboo degraded under harsh steam conditions, resulting in high aromatic and polymeric features for the HTS-tar. The significant differences between LTS-tar and HTS-tar require different techniques to achieve the resource utilization of wastewater in the bamboo industry.

Catalytic influence of iron oxide (Fe2O3) on coal pyrolysis and char combustion at various temperatures

The conversion of coal into cleaner energy forms is essential for achieving sustainable development. This study investigates the role of Fe2O3 as a catalyst in enhancing the efficiency of coal pyrolysis and char combustion. A fixed-bed tube furnace (TF) was selected for pyrolysis, and a Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectroscopy (TG-FTIR) was used for combustion analysis. The produced syngas and tar were characterized using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS). Our results show higher volatile release volume (VRV) from coal with catalyst compared with without catalyst and the rise with temperature within the 600–1000 ℃ range. Although hydrogen production decreased with the addition of the catalyst, at 1000 ℃, the catalyst's impact was negligible. The catalyst notably facilitated the breakdown of heavy aromatic rings in tar, eliminating triple-bond aromatic structures. In contrast, tar from raw coal exhibited a 20% yield of such structures. Scanning Electron Microscopy (SEM) revealed a cubic structure of Fe2O3 in char, with an increased surface area compared to raw coal char (338.75 m2/g vs. 313.51 m2/g). TG-FTIR analysis indicated a lower activation energy for catalysts with char combustion. Overall, Fe2O3 improves tar structure, increases char surface area, and lowers activation energy.

Co-gasification of waste shiitake substrate and waste polyethylene in a fluidized bed reactor under CO2/steam atmospheres

This study investigated the co-gasification of agricultural and plastic wastes, which is a potential method for waste disposal. Waste shiitake substrate (WSS) and polyethylene (PE) were selected and their properties were investigated. The thermal degradation behavior and gases produced were explored using thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG-FTIR). In addition, the activation energy was determined by the FWO method, and the synergistic effect and gas yield were estimated. The co-gasification of WSS and PE assisted by CO2 and steam was conducted using a bubbling fluidized bed gasifier. Results indicate that BR60 % had the maximum C–O band, C–C bond, C–H band, and CO yields. Blending WSS and PE resulted in an evident synergistic effect. The activation energies of BR20 % had the lowest value. The Taguchi method was used to determine the optimal parameters, maximum normalized H2 concentration, H2/CO ratio, CGE, and exergy efficiency. The H2 yield and H2/CO ratio were predominantly affected by the CO2/(CO2+H2O) ratio, and the best concentration and ratio were 28.6 % and 1.34. The CGE and exergy efficiencies were predominantly affected by gasification temperature, and the best results were 71.6 % and 72.4 %, respectively. Finally, the collected tars were analyzed using gas chromatography-mass spectrometry (GC/MS).

Pyrolysis behaviour of shellfish waste via TG-FTIR and Py-GC/MS

Shellfish waste (SW), a by-product of seafood processing and consumption, poses ecological concerns from improper management, resulting adverse effects such as water pollution, habitat degradation, and destruction of local ecosystems. Furthermore, the inefficient disposal of SW goes against the principles of circular economy and resource utilization. Therefore, this study is conducted to convert and reuse SW and transform it into value-added products, thereby contributing to sustainable waste management practices. Shellfish waste was characterized for its elemental and proximate contents, followed by performing pyrolysis of SW to study the pyrolysis behaviors and chemical composition of pyrolytic products. Thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) was employed to identify the optimal pyrolysis temperature range (660–780 °C). Additionally, pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS) was utilized to analyze gaseous products generated from SW pyrolysis. The analysis revealed that SW possesses a low high calorific value (5.57–8.05 MJ/kg) and high H/C (0.3–1.3) and O/C (3.2–5.2) ratios, rendering it unsuitable for direct use as fuel. Optimal pyrolysis conditions were identified within the temperature range of 660–780 °C through TG-FTIR analysis. Py-GC/MS analysis at 700 °C and a heating rate of 30 °C/min indicated that carboxyl compounds (37.3–87.0%) constituted the dominant components of gaseous products generated during SW pyrolysis. In conclusion, the study underscores the promise of pyrolysis as a viable method for transforming SW into value-added chemicals. The findings of this study contribute to the advancement of sustainable waste management strategies and the utilization of waste materials for valuable purposes in various industries.

Explosibility and thermal decomposition behavior of nitrile rubber dust in industrial processes

The formation of nitrile rubber (NBR) dust clouds during processing can lead to a potential dust explosion under certain conditions. However, the potential explosion hazard posed by NBR dust is usually overlooked by enterprises. In this paper, the explosive properties of NBR dust are investigated using a Hartmann tube, a G-G furnace, and a 20 L explosion chamber. The results showed that NBR dust could cause explosions severe enough to be classified as St-1. In addition, the thermal decomposition behavior of NBR dust under combustion conditions was investigated using a combination of thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TGA-FTIR). The results indicated that in the early stage, NBR dust mainly undergoes self-thermal decomposition to produce a large amount of combustible gas, which combines with oxygen to form a mixed gas and cause a gas-phase explosion. In addition, the participation of oxygen could lower the initial temperature of NBR dust thermal decomposition. As a result, decomposition occurred more quickly and a large amount of combustible gas was produced, thus expanding the range of dust explosions. Furthermore, these combustible gases exhibit varying degrees of toxicity, seriously affecting the life and health safety of relevant personnel. This work provides theoretical guidance for the development of safe procedures to prevent and address problems during NBR dust processing in enterprises.

Pyrolysis products from various types of plastics using TG-FTIR at different reaction temperatures

Pyrolysis products of low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and municipal plastic waste at different reaction temperatures were predicted in the current study using a newly developed thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) method. The experiments revealed that pyrolysis products of LDPE and PP at 500 °C were almost wax. Above 600 °C, wax formed from LDPE and PP almost disappeared, while the production of light hydrocarbons was enhanced. In the cases of LDPE and PP, the benzene and toluene formations were clearly observed above 800 and 700 °C, respectively. For PS, styrene was observed as the major component at 500–800 °C. With increasing temperature, the formations of alkenes, benzene, and toluene were enhanced at the expense of styrene. Different from other plastics, PET produced a pyrolysis vapor containing mainly CO2 and CO. FT-IR spectra of PET were almost unchanged despite increasing temperature above 600 °C. In the case of municipal plastic waste, the product distribution was similar to those of LDPE and PP. The new TG-FTIR method turned out to be an effective tool to predict pyrolysis products, especially gases products having low molecular weights.

Thermokinetics and gas emission characteristics of nitrification waste under different oxygen contents by using TG-FTIR technique

Nitrification waste has been a main hazard factor in many fire and explosion accidents; however, its thermal characteristics, which provide critical information for hazard control, have not been extensively studied. Accordingly, this study investigated the thermokinetic parameters and gas emission behaviors of nitrification waste by using thermogravimetric analysis coupled with Fourier transform infrared spectrometry (TG-FTIR). A reaction environment with various oxygen contents (0%, 15%, 21%, and 30%) was created.Both integral method (Starink method)and differential method (Friedman method) were adopted to analyze the activation energy of nitrification waste. The results revealed that the thermal decomposition of nitrification waste could be divided into three stages and that the activation energy of this waste was a quadratic function of the oxygen content. The results of this study can improve the understanding of the thermal behavior of nitrification waste and can thus serve as a reference for the effective prevention of related thermal hazards.

Catalytic dehydrogenation cracking of crude oil to light olefins by structure and basicity/acidity adjustment of bifunctional metal/acid catalysts

Catalytic dehydrogenation cracking of crude oil to light olefins (CTO) was carried out by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and a fluidized bed reactor. Cracking characteristics, apparent kinetics, and product release rules of CTO were analyzed by the thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Results showed that dehydrogenation-cracking bifunctional catalysts could be obtained only when the properties of metals matched with acid catalysts. The bifunctional 1%Ca/ZSM-5 (1Ca/ZSM-5) catalysts can increase dehydrogenation, attenuate hydrogen transfer, and inhibit coking. Consequently, light (C2-C4) olefins produced from 1Ca/ZSM-5 catalyst were enhanced significantly. There were mainly-two stages of pyrolysis and catalytic dehydrogenation cracking in the catalytic conversion of crude oil. The activation energy of bifunctional 1Ca/ZSM-5 catalyst decreased in the pyrolysis stage. The product adjustment mechanism by bifunctional catalysts was proposed from the perspective of structure and basicity/acidity, which would guide the maximization production of light olefins.

Deciphering the effect of the heat treatment on the electrodeposited silicon anode for Li-ion batteries

In this study, we report a facile way to improve the stability of electroplated Silicon (Si) electrodes through heat treatment. Electrodeposition of Si is carried out on a porous current collector followed by the heat treatment under an oxygen-free environment at 300 °C, 350 °C, and 400 °C. It is shown that as the heat treatment temperature increases, the cycling stability of the Si anode also dramatically improves. The Si electrode heat treated at 400 °C also keeps the quality of Si even after exposing the electrode to the air for up to 7 days which relieves the handling burden of Si in the ambient atmosphere. The striking difference allows the Si electrode heat treated at 400 °C to maintain its 77 % capacity even after exposure to air for one week. The outstanding electrochemical performance of the electrodeposited Si electrodes heat treated at various temperatures is characterized by thermogravimetric analysis coupled with fourier transform infrared spectroscopy (TGA-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) coupled with energy dispersive spectrometry and selected area electron diffraction (SAED), Raman spectroscopy, electrochemical cycling, and electrochemical impedance spectroscopy (EIS) techniques.

Thermal degradation and pyrolysis behavior of wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters

In this study, the thermal degradation and pyrolysis behavior of three wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters (TLCP) were investigated. The non-isothermal degradation kinetic parameters were determined using the Kissinger and Friedman method. The copolyesters exhibited two degradation stages in air but only one in N2, and better thermal stability was observed for those containing more 10-(2,5-Dihydroxypheny)-10 h-9-oxa-10-phospha-phe-nanthrene-10-oxide (DOPO-HQ) units, which could be reflected by the thermogravimetric analyzer (TGA) data and E values. The TGA coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas chromatograph-mass spectrometer (Py-GC-MS) results showed that DOPO-HQ decomposed first in the early stage of degradation, generating gaseous pyrolysis products and forming phosphorus-containing char residue in the later stages of degradation. However, the copolyesters produced more CO2 and less organic volatiles during thermal oxidative degradation. The morphology and FTIR spectra of the char residue obtained after TGA experiments showed a continuous and dense structure due to the presence of phosphorus moieties. The microscale combustion calorimeter (MCC) and limiting oxygen index (LOI) results showed that the copolyesters have excellent flame retardant properties, and the LOI value increases monotonically with increasing of DOPO-HQ content, having a maximum value up to 73.8%, due to its excellent gas-phase and condensed-phase fire inhibition mechanisms. Overall, the resulted phosphorus-containing thermotropic liquid crystal copolyesters exhibited excellent thermal stability and flame retardancy, the thermal degradation and pyrolysis research would be a good guidance for its processing and application.

Investigating the trigger mechanism of Shenfu bituminous coal pyrolysis

This work aims at exploring the trigger mechanism of Shenfu bituminous coal pyrolysis. Flash pyrolysis technique combined with gas chromatography-mass spectrometry (Py-GC/MS), thermogravimetric analysis (TGA) coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and reactive molecular dynamic simulations (ReaxFF MD) were employed in elucidating the trigger mechanism of coal pyrolysis. The proposed coal model was C1328H1130N21O245S7, whose pyrolysis was simulated using ReaxFF MD. Simulation results showed that the pyrolysis process could be divided into activation, decomposition and recombination stages, which agreed well with the experimental weight loss. Based on evolutions of gas species, it was found that the generation of gases was caused by the cleavage of oxygen-containing groups during the activation stage. Simulation results with the unimolecular of Shenfu coal showed that the order of chemical bond cleavage was C-O-C<CO<aromatic-CH<COOH in the activation stage. The variation of chemical bond agreed well with those from TGA-FTIR and Py-GC/MS analyses, indicating that the simulated results are valid and convincing. Therefore, it was concluded that the free radical reactions responsible for gas generation were caused by the cleavage of oxygen-containing functional groups, and this was also the trigger mechanism of coal pyrolysis.

Co‐combustion characteristics of black liquor and waste oil sludge

In this study, the co-combustion of black liquor and oil sludge is investigated. The properties of the fuels are analyzed, and the co-combustion characteristics are explored by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR). The synergistic effect, activation energy as well as gas yield are also studied from TG-FTIR results. The results show that the addition of oil sludge can promote the reaction in the early stage, as indicated by the combustion characteristic index and the flammability index. The TG-FTIR also shows that the swelling behavior of black liquor appears to block the release of volatile matter. The weaker SO2 emission and XRF analysis for the black liquor indicate that most of the sulfur remained in the ash. A positive synergy effect existed in the early stage, and the activation energy decreased with the addition of oil sludge. Distinct stages could be observed in the single pellet combustion experiments. Adding oil sludge to the black liquor promoted surface bubbles and ash melting. Surface bubbles indicate more volatile breaks through the plastic state layer formed on the black liquor and increase the reaction. However, adding oil sludge should be controlled to reduce the hindrance to the reaction due to ash melting.

Catalytic upgrading of coal volatiles with Fe2O3 and hematite by TG-FTIR and Py-GC/MS

Pyrolysis plays a critical role in clean coal technology and energy conversion and is also conducive to the early peaking of carbon dioxide emissions. Light tar production from traditional coal pyrolysis using various iron-based catalysts for chemicals and fuel oil has gained attention recently. In this study, waste hematite was initially used for catalytic upgrading of rapid coal pyrolysis. Subsequently, thermogravimetric analyzer coupled with Fourier-transform infrared spectrometry (TG-FTIR) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) were utilized to compare the performances, kinetic parameters, and volatile composition of coal pyrolysis with Fe2O3 and hematite. The results showed that the maximum weight loss rate of coal pyrolysis increased by 1.55 %/min and 0.32 %/min with the addition of Fe2O3 and hematite, respectively, indicating that the pyrolysis reaction became more rapid and intense with iron-based catalysts. Both Kissinger Akahira Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods revealed that the catalysts reduced the apparent activation energy of coal pyrolysis. Online FTIR showed the emission temperature and content of coal volatiles, suggesting iron-based catalysts were conducive to the cracking of oxygen-containing functional groups and the directional cracking of groups to CO. Py-GC/MS illustrated the presence of Fe2O3 and hematite could reduce polycyclic aromatic hydrocarbons and oxygenates. In addition, a mechanism for rapid coal pyrolysis with iron-based catalysts was proposed to provide fundamental information for the transformation of aliphatic hydrocarbons, oxygenates, and polycyclic aromatic hydrocarbons. It is believed that iron-based catalysts have great potential for future research on upgrading coal volatiles and tar.

Castor 오일과 HER 기반 폴리우레탄: 합성, 분석, 구조-열 안정성 상관관계

Polyurethanes (PUs) were prepared from solvent and catalyst free reaction mixture containing polyethylene glycol (PEG), 4,4’-methylene diphenyl diisocyanate (MDI) and 1,3-bis(2-hydroxyethoxy) benzene (HER) and/or castor oil (CAO). PUs were characterized using the Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopic methods. Thermal studies on PUs using differential scanning calorimetric (DSC) and thermogravimetric analysis coupled with FTIR (TG/FTIR) proved that CAO-extended PUs were thermally more stable than HER extended PUs. The partial and complete replacement of HER content in PUs using CAO enhanced the thermal stability by shifting degradation temperature to higher temperature (5-15 ℃) and enhancing the char residue. The parameters derived from DSC traces, thermogram and differential thermogram confirmed that PUs synthesized using PEG 1500 are thermally more stable than the PUs prepared using PEG 4000. The probable degradation mechanism to study the role of β-hydrogen on the thermal stability was proposed and discussed based on the results of TG/FTIR.

Strategic hazard mitigation of waste furniture boards via pyrolysis: Pyrolysis behavior, mechanisms, and value-added products

Waste furniture boards (WFBs) contain hazardous formaldehyde and volatile organic compounds when left unmanaged or improperly disposed through landfilling and open burning. In this study, pyrolysis was examined as a disposal and recovery approach to convert three types of WFBs (i.e., particleboard, plywood, and fiberboard) into value-added chemicals using thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG-FTIR) and pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS). TG-FTIR analysis shows that pyrolysis performed at an optimum temperature of 250–550 °C produced volatile products mainly consisting of carbon dioxide, carbon monoxide, and light hydrocarbons, such as methane. Py-GC/MS shows that pyrolysis at different final temperatures and heating rates recovered mainly phenols (25.9–54.7%) for potential use as additives in gasoline, colorants, and food. The calorific value of WFBs ranged from 16 to 18 MJ/kg but the WFBs showed high H/C (1.7–1.8) and O/C (0.8–1.0) ratios that provide low chemical energy during combustion. This result indicates that WFBs are not recommended to be burned directly as fuel, however, they can be pyrolyzed and converted into solid pyrolytic products such as biochar with improved properties for fuel application. Hazardous components, such as cyclopropylmethanol, were removed and converted into value-added compounds, such as 1,4:3,6-dianhydro-d-glucopyranose, for use in pharmaceuticals. These results show that the pyrolysis of WFBs at high temperature and low heating rate is a promising feature to produce value-added chemicals and reduce the formation of harmful chemical species. Thus, the release of hazardous formaldehyde and greenhouse gases into the environment is redirected.

Thermochemical Conversion Behavior of Turkish Lignite/Poppy Capsule Pulp Blends in N2 and CO2 Atmospheres

In this study, Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectroscopy (TGA-FTIR) was used for the determination of the thermochemical conversion reactivity of two different types of Turkish lignite coal (Tunçbilek and Orhaneli-Gümüşpınar) and poppy capsule pulp (PCP) mixtures under pyrolysis conditions at nitrogen (N2) and carbon dioxide (CO2) atmospheres. Activation energies (Ea) and pre-exponential factors (A) were determined according to Coats-Redfern method and first-order reaction model. In CO2 atmosphere, all samples exhibited an extra weight loss around 800 - 850 ° C, different from the N2 atmosphere, due to the reactive nature of CO2 during thermal decomposition. FTIR analysis confirmed this finding, at high temperatures CO formation were observed in the CO2 atmosphere. In all mixtures, the third zone experimental decomposition temperature is lower than that obtained theoretically in N2 atmosphere, showing that there might a synergistic interaction between the PCP and the lignite samples. The Ea of PCP/Tunçbilek lignite mixtures are smaller than the Ea of their parent components indicating synergy in N2 and CO2 atmospheres. However, initial and maximum decomposition temperatures for the parent components remain unchanged for these mixtures. Moreover, especially at temperatures higher than 600 °C, the Ea for biomass/lignite mixtures found lower than the theoretical values, due to the possible synergistic interactions between PCP and coal samples. According to FTIR analysis, CO, CH4, CHn and ether/amine components were detected. Gaseous pyrolysis product compositions were highly dependent on temperature, and gas species formation was consistent with the weight loss of samples.

Characteristics and kinetics of the gas releasing during oil shale pyrolysis in a micro fluidized bed reactor

This paper presents a comprehensive study on characteristics and kinetics of the gas component (H2, CH4, CO, CO2) releasing during oil shale (OS) pyrolysis. Firstly, the thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TGA-FTIR) was used to determine the decomposition regions of OS. The results showed that the OS undergoes two pyrolysis regions: first stage (400∼600 °C) and second stage (600∼800 °C). The isothermal pyrolysis of OS was carried out in a micro-fluidized bed reaction analyzer (MFBRA). The evolved temperature and time span of each gas product are different in both sections. Reaction kinetics were investigated with respect to the formation of individual gas component and gas mixture. The kinetics of gas components and gas mixture were calculated by model fitting method. The activation energy (Ea) calculated by the three models for H2, CH4 and CO2 were in the range of 51.05∼60.15, 6.84∼9.65 and 13.21∼14.10 kJ/mol, respectively, while the values varied significantly in high temperature zone. In particular, the resulting Ea values for H2 decreased to 38.88∼40.57 kJ/mol, while that for CH4 and CO2 increased to 25.16∼27.61and 26.12∼35.12 kJ/mol, respectively. However, compared with other three gases, CO only appears in the high temperature zone, and the activation energy of CO is in the range of 32.98∼34.82 kJ/mol. The Ea of the stage 2 is higher than that of the stage 1. The result indicated that the control step gradually transits from the surface chemical reaction control to the joint control of reaction and diffusion with increasing temperature.

Locally Sustainable Biodiesel Production from Waste Cooking Oil and Grease Using a Deep Eutectic Solvent: Characterization, Thermal Properties, and Blend Performance.

As part of local sustainability efforts, biodiesel was synthesized via transesterification using a deep eutectic solvent (DES) without further washing from on-campus, dining facility waste cooking oil and grease. Before moving forward with repurposing used DES as a solvent in chemistry teaching labs, we determined the suitability of the biodiesel as an alternative fuel blended with diesel to power campus utility vehicles. Biodiesel components were characterized by gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H NMR), viscometer, differential scanning calorimetry (DSC), and evolved gas analysis during pyrolysis with a thermogravimetric analyzer coupled with FTIR (TGA-FTIR). The four major components of fatty acid methyl esters (FAMEs) in the biodiesel were methyl oleate, methyl linoleate, methyl palmitate, and methyl stearate. Kinematic viscosity over typical temperature ranges was within optimal values recommended by the American Biodiesel Standard (ASTM D6751), with a 30:70 biodiesel/diesel blend experimental viscosity of 3.43 cSt at 40 °C and a calculated viscosity of 10.13 cSt at 0 °C. The pure biodiesel’s cold-temperature onset of crystal formation is −10.1 °C versus −16.4 °C for a 30:70 biodiesel/diesel blend. Pyrolysis indicates good thermal stability, however, with an increased CO2 evolution in the blended fuel at higher temperatures as compared to that in the pure biodiesel and the pure diesel. Combustion gas analysis indicates virtually complete combustion of the blended fuel to CO2 and H2O with only trace amounts of CO. Overall results indicate that the biodiesel synthesized using DES is a suitable fuel for campus utility vehicles in the local moderate temperature climate and affords increased local sustainability by using used DES repurposed in our chemistry teaching labs.

Analysis of Pyrolysis Characteristics and Kinetics of Cigar Tobacco and Flue-Cured Tobacco by TG-FTIR

Summary Investigation of the detailed pyrolysis characteristics of tobacco raw materials is important for the understanding of product design and consumption. In this work, pyrolysis characteristics and kinetic models of cigar filler tobacco (CFT), cigar wrapper tobacco (CWT), and flue-cured tobacco (FCT) were investigated by using a thermogravimetric analyzer coupled with Fourier-transform infrared spectroscopy (TG-FTIR). The pyrolysis of different tobacco samples could be divided into four stages based on the derivative thermogravimetric analysis (DTG) curves. Flue-cured tobacco underwent a marked decomposition process at lower temperatures (about 200 °C), while the thermal decomposition of cigar tobacco occurs at higher temperatures. During the pyrolysis process, evolved gases including H2O, CO2, CH4, CO, carbonyls, alcohols, phenols and aromatic compounds were detected by FTIR. CWT released more CO2 than CFT, while the amount of CO2, CH4, CO and aromatic compounds released by flue-cured tobacco was lower than that of cigar tobacco. The pyrolysis kinetics of tobacco leaves were further analyzed and compared through the isoconversional FWO (Flynn-Wall-Ozawa) and KAS (Kissinger-Akahira-Sunose) methods. The activation energy of FCT (from 100.1 kJ mol−1 to 192.1 kJ mol−1) was lower than that of CFT (from 207.36 kJ mol−1 to 319.28 kJ mol−1) and CWT (from 160.40 kJ mol−1 to 260.45 kJ mol−1). The thermal decomposition kinetics of different tobaccos were analyzed by Málek and Coats-Redfern methods.