Higher Final Temperature Research Articles

Microwave plasma conversion of food waste using carbon foam: Production of heteroatom-doped graphene and combustible gas

The mass production of food waste (FW) has a terrible impact on the environment, but with proper treatment, FW can be transformed into a new resource. Currently, thermal conversion (especially incineration) has been the most common and efficient means of handling FW, but it also entails negative impacts, such as high carbon emissions and lower added value. In this study, a new high-efficiency thermal conversion process is proposed that uses carbon foams to induce the formation of microwave plasma (MP), which generates very high final temperatures to enable the direct conversion of FW into combustible gases and high-value-added heteroatom-doped microwave plasma graphene (HMPG) in 5–20 s. This work investigated the optimal carbonization temperature of the melamine sponge (carbon foam precursor) and the effect of microwave plasma reaction duration on the distribution of the gas products and the properties of HMPG, and HMPG was characterized in detail by Raman spectroscopy, X-ray diffraction, scanning electron microscope, etc. Ultimately, HMPG was tested in potassium ion battery anodes for evaluation of its energy storage potential, and the results showed that the capacities were able to reach ∼270 mAh g−1 at 50 mA g−1 after 60 cycles.

Experimental Study on Microwave Drying Aluminum Hydroxide

The aluminum hydroxide produced by the Bayer process contains a large amount of water which leads to the consumption of a large amount of heat for moisture removal in the calcination process, resulting in an increased energy consumption. The effects of temperature and microwave power on the dehydration ratio and the dry matter ratio of aluminum hydroxide were investigated. The characteristics of temperature variation during drying were discussed. X-ray diffraction (XRD), scanning electron microscopy (SEM), laser particle size, Fourier transform infrared (FTIR) spectroscopy, and dielectric property analyses were made to characterize the dried materials. The analysis results showed that within the range of bench-scale experimental parameters, the dehydration ratio was higher and the proportion of dry matter was lower at a higher final temperature. Within the range of pilot-scale experimental parameters, the dehydration ratio increased with the increasing microwave power from 500 W to 1500 W. XRD spectra revealed that when the final temperature exceeded 220 °C, a part of the aluminum hydroxide underwent a low-temperature phase transition to boehmite. The SEM images and a particle size analysis showed that there was no significant difference between the morphologies of the powder obtained by microwave drying and conventional drying methods. The powder obtained by both processes had an average particle size of around 80 μm. The dielectric constant and the dielectric loss of the dried material decreased greatly.

Measuring aliphatic hydrocarbons in sediments by direct thermal desorption-gas chromatography-mass spectrometry: Matrix effects and quantification challenges

Direct sample introduction thermal desorption (TD) coupled to GC–MS was investigated for the analysis of paraffinic hydrocarbons (HCs) from polluted sediments. TD-GC–MS is sometimes used for analysing paraffinic HCs from atmospheric particles but rarely for their direct desorption from sediments. So, the new TD methodology, applied to sediments, required development, optimization and validation. A definitive screening experimental design was performed to discriminate the critical factors on TD efficiency, from model sediments containing various organic matter (OM) amounts. Low molecular weight HCs had extraction behaviours markedly different from high molecular ones (HMW-HCs), but a compromise was found using very few sediment amount (5 mg), high temperature rate (55 °C min−1) and final temperature (350 °C). Linear HCs (n-C10 to n-C40) could be quantified using the matrix-matched calibration method, with very low detection limits (3.8–13.4 ng). The amount of the overall paraffinic alkanes was also determined as a sum of unresolved components between predefined equivalent carbon ranges. The developed solventless methodology was compared to an optimized solvent microwave assisted extraction (MAE). Matrix effects could be higher for TD compared to MAE but it depended on sediment matrix. When matrix effect was strong, particularly on HMW-HCs signal depletion, a dilution with pure non-porous sand was favourable for accurate quantification. The sum of resolved and unresolved HCs gave comparable results between MAE and TD extractions, with an exception of alkanes greater than C30 which were less quantitatively extracted via TD. However, TD-GC–MS was more sensitive than MAE-GC–MS. So TD-GC–MS is useful for analyzing sediments containing a great range of paraffinic HCs (C9-C34) and it has the advantages of being fully automated, with few sample preparation and operator intervention, using very low amounts of solvent, and generating few wastes.

Pyrolysis and Torrefaction-Thermal Treatment of Creosote-Impregnated Railroad Ties as a Method of Utilization.

A fundamental issue of waste management and the rail transport industry is the problem of utilizing used railroad ties. Wooden railroad ties are treated with a preservative, usually creosote. Due to their high toxicity, railroad ties are considered hazardous waste and must be utilized under various directives. It is proposed to utilize the troublesome waste by using the pyrolysis and torrefaction process. The research proves that the thermal method is effective for disposing of this type of waste. Torrefaction up to 250 °C gives high efficiency of impregnation removal, while pyrolysis up to 400 °C completely neutralizes waste. A series of experiments were conducted for various final pyrolysis temperatures to determine a minimum temperature for which the obtained solid products are free from creosote. Extraction with the use of the Soxhlet technique was performed for the raw materials and the obtained solid products-chars. The oil content for liquid fraction was also examined for each sample. As a result of the thermal treatment of the waste, fuel with combustion parameters better than wood was obtained. For a high final temperature of the process, the calorific value of char is close to that of hard coal.

Copioba and common cassava flour know-how: Establishing similarities and distinctions in São Felipe, Brazil

In Brazil's Recôncavo Baiano region, Copioba flour is a traditional product of notoriety and potential for Geographical Indication. Studies have been conducted to characterize this flour, although descriptions of its production process and the orally-transmitted know-how involved are lacking. This study sought to describe Copioba cassava flour (COPF) know-how, comparing it to the common cassava flour process (COMF), considering the experience of a renowned flour producer. For this purpose, the research relied on-site monitoring with data collection through observation of activities, in dialogue with the producer; field diary records, and photographic register, observing a work script and the production stages. The time of each step and the roasting temperature were also monitored. The main differences in production included five steps: peeling/scraping; crushing; crumbling and roasting, for which COPF had a shorter time (average 60 min), with a higher final temperature (115 °C), recording 80 min and 103 °C for COMF - the opposite, probably due to the larger size of the agglomerates of this dough. The findings show differences in the application of the producer's know-how, using his traditional knowledge and accumulated experience. This results in different flours, with COPF prepared under a more careful elaboration, which justifies its notoriety.

Controlling Laser Irradiation with Tissue Temperature Feedback Enhances Photothermal Applications: Ex-Vivo Evaluation on Bovine Liver

Achieving repeatable and successful results without causing excessive collateral damage is of paramount importance for photothermal laser applications. Predetermined laser parameters cannot ensure patient safety and treatment success due to variance between optical and thermal characteristics among subjects. Controlling laser irradiation with tissue temperature feedback is the current gold standard for various photothermal treatments (PTT) which are rate processes described by the Arrhenius temperature integral. This study establishes the validity of our low-cost design that makes tissue surface temperature control during photothermal laser applications more accessible in resource limited clinical environments. We demonstrated the practical performance and potential of our system with ex-vivo bovine liver irradiation using an ytterbium fiber laser (λ=1071 nm) with two independent variables: laser power (3.4 W, 6.8 W and 10.2 W) and target surface temperature (55 °C, 65 °C and 75 °C). Our system efficiently maintained tissue surface temperatures at target values in all laser power groups. In contrast, fixed-dose application groups displayed a high final temperature range and variation in the control experiment. Temperature–time responses of samples varied significantly, in agreement with a wide range of optical and thermal coefficients. Long exposure duration groups (lower power, higher target temperature) displayed more radical differences suggesting a dominance of optical and thermal characteristics over the response. The low-cost surface-temperature-controlled medical laser system we have developed is capable of ensuring the success and reproducibility of PTT modalities and patient safety.

Measurements of hair temperature avalanche effect with alexandrite and Nd:YAG hair removal lasers.

In this study, we investigate the photothermal response of human hair using a pulsed laser source employed in the hair removal treatment. The purpose is to understand the dynamics behind the most common clinical practice to better define the salient features that may contribute to the efficiency of the process. Temperature changes of hair samples (dark brown color) from a human scalp (skin type Fitpatrick II) were measured by a thermal camera following irradiation with single and multiple neodymium: yttrium-aluminum-garnet (Nd:YAG) (1064 nm) and alexandrite (755 nm) laser pulses. Particularly, the hair was treated with an individual laser pulse of a sufficiently high fluence, or with a series of lower fluence laser pulses. We investigated the temperature increase in a broad range of fluence and number of pulses. From the data analysis we extrapolated important parameters such as thermal gain and threshold fluence that can be used for determining optimal parameters for the hair removal procedure. Our experimental investigations and hypothesis were supported by a numerical simulation of the light-matter interaction in a skin-hair model, and by optical transmittance measurements of the irradiated hair. An enhancement of the temperature response of the irradiated hair, that deviates from the linear behavior, is observed when hair is subjected to an individual laser pulse of a sufficiently high fluence or to a series of lower fluence laser pulses. Here, we defined the nonlinear and rapid temperature built-up as an avalanche effect. We estimated the threshold fluence at which this process takes place to be at 10 and 2.5 J/cm2 for 1064 and 755 nm laser wavelengths, respectively. The thermal gain expressed by the degree of the deviation from the linear behavior can be higher than 2 when low laser fluence and multiple laser pulses are applied (n = 50). The comparison of the calculated gain for the two different laser wavelengths and the number of pulses reveals a much higher efficiency when low fluence and multiple pulses are delivered. The avalanche effect manifests when the hair temperature exceeds 45°C. The enhanced temperature increase during the subsequent delivery of laser pulses could be ascribed to the temperature-induced changes in the hair's structural properties. Simulations of the hair temperature under Nd:YAG and alexandrite irradiation indicate that the avalanche phenomenon observed in the hair suspended in air may apply also to the hair located within the skin matrix. Namely, for the same fluence, similar temperature increase was obtained also for the hair located within the skin. The observed "avalanche" effect may contribute to the reported clinical efficacy of laser hair removal and may at least partially explain the observed efficacy of the brushing hair removal procedures where laser fluence is usually low. The repeated irradiation during the brushing procedure may lead to an avalanche-like gradual increase of the hair's thermal response resulting in sufficiently high final hair temperatures as required for effective hair reduction.

Effects of variable amounts of volatiles in corncob on microwave co-pyrolysis of low-rank coal and corncob

Crop waste-assisted microwave pyrolysis of low-rank coal (LRC) can provide sufficient hydrogen for thermal decomposition reactions of LRC, which can change the pyrolysis reactions and product characteristics. To reveal the effect of crop waste as a hydrogen supply on the microwave pyrolysis of LRC, the temperature-rise characteristics, product distribution, and product characteristics of microwave co-pyrolysis of LRC and corncob (CR) with different amounts of volatiles were investigated in detail, and the crystal and chemical structures of char and tar were analyzed. The results showed that the volatiles in CR promoted the production of tar and inhibited the generation of pyrolysis gas within a certain range during microwave co-pyrolysis; however, the volatiles had the opposite effect beyond this range. With an increase in volatiles in CR, the yields of char and pyrolysis water gradually decreased and increased, respectively. CR with low amounts of volatiles at high final pyrolysis temperatures increased the specific surface area and total pore volume of the char obtained by microwave co-pyrolysis and improved the aromaticity and graphitization of char and the ordered structure of the crystal structure in char. Additionally, the formation of aromatic structures in the tar was promoted, and the contents of oxygen-containing functional groups and aliphatic hydrocarbons in the tar were reduced. The fraction of light oil in the tar increased by 18.49%, indicating that the lightness and stability of the tar significantly increased. These findings have provided a theoretical basis for microwave co-pyrolysis of LRC and crop wastes, as well as experimental evidence for regulating its product characteristics.

Effect of Iron Ore Pellet Size on Metallurgical Properties

Iron ore pellets are small and hard spherical particles agglomerated from a fine iron ore concentrate. They are used in the blast furnace process to produce hot metal. The diameter of blast furnace pellets is usually between 8 and 16 mm. In this study, a batch of magnesia iron ore pellets was first sieved into particle sizes of 8–10 mm, 10–12.7 mm, 12.7–16 mm and 16–20 mm, and the four different size fractions were used to study the effect of pellet size on metallurgical properties. The metallurgical experiments showed a decrease both in reducibility under unconstrained conditions and in low-temperature reduction-disintegration but showed an increase in cold crushing strength as the pellet size increased. In the reduction-softening test, pellets sized 10–12.7 mm reached the highest final temperature and the highest reduction degree among the pellet samples of different sizes. Based on the implications drawn from this study, the amount of 10–12.7 mm pellets should be maximized in a blast furnace operation.

Evaluation of the effect of microwave heating modes on the germination ability of lupine seeds

Technologies based on the use of the energy of electric, magnetic and electromagnetic fields can be successfully applied in agricultural production. According to the available research results, it can be quite reliably asserted that during the pre-sowing treatment of agricultural seeds, it is possible to use microwave electromagnetic fields. A feature of such technologies is the experimental determination of the parameters of microwave exposure. The materials of the article contain the results of experimental studies to assess the temperature effect of microwave energy on the germination ability of lupine seeds. Regression equations are obtained in coded and natural variables to assess the effect of the final temperature and microwave heating rate on the germination ability of lupine seeds. Analysis of the results obtained indicates that the final result of microwave seed treatment depends on each factor separately and on their relationship. In addition, it is necessary to strictly observe the processing regimes, since the seeds are sensitive to energy effects and, in addition to the stimulation effect, you can get a negative result or get into the zone of insensitivity. According to the data obtained, the best result of microwave stimulation of lupine seeds is observed when the seeds are heated to 50 °C at a heating rate of 0.46 °C/s. Compared to the results of wheat seed treatment, higher final temperatures and microwave heating rates are required to stimulate lupine seeds. In addition, for a positive result of processing, it is necessary to take into account that the microwave heating rate of the seeds determines the final temperature of their heating. To stimulate lupine seeds, it is possible to recommend microwave heating to 50-51 °C at a microwave heating rate of 0.46-0.47 °C/s.

Глубина прогрева потока газовзвеси встречным излучением

Выполнена аналитическая оценка отношения глубины прогрева газовзвеси излучением продуктов горения S к длине свободного пробега излучения в газовзвеси L. Использована одномерная модель стационарного распределения температуры в потоке взвешенных в воздухе монодисперсных инертных частиц, движущихся на равномерно нагретую абсолютно черную поверхность, имитирующую фронт пламени. Учитывается отражение и переизлучение тепловой энергии частицами. S / L >> 1 при низкой степени черноты и/или высокой конечной температуре частиц. It is accepted that the depth of heating of the gas suspension by the radiation of combustion products SR is equal to the length LR of the free path of radiation in the gas suspension: SR ≈ LR. Numerical simulation of gas-air mixture combustion with the addition of inert particles, taking into account the re-emission of heat by heated particles of fresh suspension, shows the possibility of realizing the ratio SR >> LR (Ivanov M.F. et al, 2015). In this work, an analytical estimate of the SR/LR ratio is carried out within the framework of one-dimensional modeling of the temperature distribution in the flow of initially cold monodisperse inert particles suspended in air, moving to a uniformly heated absolutely black surface, permeable to air suspension and simulating a flame front. The following assumptions are used. The solution is stationary in the coordinate system associated with the emitting surface; radiation consists of two oppositely directed streams of electromagnetic energy; the interaction of particles and radiation is described in the approximation of geometric optics and takes into account both the processes of absorption and emission of thermal energy, and the process of reflection of radiation; the temperature inside the particle is the same. In contrast to the previously considered (Poletaev N.L., 2021) the simplified problem of the motion of particles in a vacuum or in the presence of a gas phase heated by particles but not experiencing thermal expansion, this work took into account both the presence of a gas phase heated by particles and expansion of the gas phase. The latter causes the acceleration and expansion of the air suspension as it approaches the radiating surface. The difference in the local values of temperatures and phase motion velocities of the air suspension was neglected. It is shown that the quasi-linear (in the above-mentioned coordinate system) temperature distribution function in the air suspension obtained in this work is qualitatively different from the quasi-exponential temperature distribution function obtained earlier by solving a simplified problem. At the same time, the ratio of the heating depth of the air suspension by thermal radiation and the free path of radiation in the layer of air suspension adjacent to the radiating plane turned out to be similar to that obtained for the simplified solution. Namely, SR/LR >> 1 at a low integral degree of emissivity of the particle material and / or at a high final temperature of the particles, comparable to the temperature of the emitting surface.

A study on natural luffa seed oil as a potential source of polymers and bioactive compounds

Luffa seeds are rich in resources, although they are considered as agricultural waste and thus underutilized. The main objective of this study was to investigate the application prospect of luffa seed oil (LSO) in natural polymer composites, cosmetics, functional materials, and other fields. The extraction yield, fatty acid composition, bioactive components, thermal stability, and physicochemical properties of LSO were systematically investigated. The results of extraction yield and gas chromatography–mass spectrometry analysis indicated that the extraction yield of LSO is high (36.24–39.48 %) and is rich in unsaturated fatty acids (70.97–75.03 %). Moreover, LSO is rich in bioactive substances (31 types) such as squalene, (E)-2-decenal, etc. These results indicate that LSO has promising applications in polymer composites and bioactive substance utilization. 1H NMR, 13C NMR, and FTIR spectroscopy analyses showed that LSO contains sufficient chemical reaction sites (e.g. ester groups, unsaturated double bonds, etc.), and the average double bond number of LSO molecules is 2.69–3.29. These results further indicate its greater potential for the development of polymer composites, in particular, more elastic polyurethane foams. Moreover, analysis of the thermogravimetric and physicochemical properties of LSO revealed that LSO has a relatively high iodine value (83.17 g I2/100 g), and high peak degradation temperature (371.89–422.5 °C) and final degradation temperature (490.36–501.80 °C), which is favorable for its thermal polymerization at high temperature for the preparation of polymers.

The Effect of Biogas Purification Using Biochar from Biogas Waste on Biogas Combustion

This research aimed to investigate the capability of a combination of adsorbents, biochar from biogas waste, and zeolite for improving the calorific value of biogas. There were six treatments of adsorbents, 0% volume of biochar and 100% volume of zeolite (ZZ); 25% volume of biochar and 75% volume of zeolite (AZ1); 50% volume of biochar and 50% volume of zeolite (AZ2); 75% volume of biochar and 25% volume of zeolite (AZ3); 100% volume of biochar and 0% volume of zeolite (AA). First, biogas waste was converted to biochar by pyrolysis. Then biogas was purified using this biochar and analyzed its calorific value before and after purification. The calorific value test was conducted by heating water using biogas energy. The results showed that biogas purification affected on final temperature of water heating significantly. The highest final temperature was performed by biogas purification using 75% volume of biochar and 25% volume of zeolite (AZ3). Biogas purification was not affected on calorific value significantly but affected the temperature change of heating water.

OPTIMASI KONSENTRASI ETHYLENE GLYCOL FLUIDA KERJA PADA PERANCANGAN PARABOLIC TROUGH CONCENTRATOR DENGAN REPLEKTOR

An excellence innovation for reducing greenhouse gases are done by developing a new water heater model for household applications. The application of the new model water heater by utilizing Parabolic Trough Concentrator with an indirect heating system uses heat transfer fluid able to improve the reliability of water heater compared to the thermosyphon model. Optimization for the new model is done by enhancing the reflector material and also heat transfer fluid. The experiment is done by applying the same standard measurement in order to set an adequate data for each model. The optimal reflector for the system to concentrating the solar power is polymer substrate as the fluid heated faster. The water-based solution with ethylene glycol 50:50 (v/v) for heat transfer fluid shows the best performance by achieving 98,2 oC for the 10th minute, and after one hour, the final temperature is 100,5 oC. By using a polymer substrate as a reflector for the Parabolic Trough Concentrator and using heat transfer fluid based on ethylene glycol water-based solution by concentrator 50:50 (v/v) shows the best performance among all sample with the fastest heating rate and the highest final temperature after the one-hour experiment. It shows this model has advantages to improve the system reliability by increasing the heating rate of the heat transfer fluid, which able to heat the water on the system faster.

Inherently Safer Design for low-temperature process during depressurization: An industrial case study

The exploitation of a low-quality gas field with high CO2 concentration is more viable through liquid CO2 produced from cryogenic distillation technology. Despite the bright potential of the technology, there are deficiencies in handling high concentration of CO2 at low temperature and high pressure during the blowdown condition. This study focuses on the CO2 blowdown at a cryogenic pilot plant designed to manage high concentrations of CO2 in the feed gas, high pressures, and low temperatures. A comprehensive design review and risk assessment using Inherent Safer Design (ISD) indexes were carried out in this study. The ISD was performed to identify the current risk level, and the critical parameters that may cause solid CO2 formation in the piping or equipment as well as to identify mitigation measures to avoid the temperature to drop below the CO2 freezing point during blowdown. The present findings confirmed that the initial pressure and temperature, as well as CO2 concentration are key parameters towards significant impact on blowdown conditions. Therefore, the reduction of the feed gas pressure from 80 bar to 70 bars has minimized the Joule Thomson (JT) effect during blowdown and avoided the CO2 solid formation in the system. Moreover, the relocation of the blowdown valve at the downstream heater resulted in a higher final temperature above the CO2 freezing point. The ISD indexes confirmed that the cryogenic facilities are inherently safer during blowdown with the mitigation measures adopted.

A highly stable hydroxylated graphene/ethylene glycol-water nanofluid with excellent extinction property at a low loading for direct absorption solar collectors

In order to explore a graphene-containing nanofluid with good dispersion stability as the working fluid for a low-temperature direct absorption solar collector (DASC), firstly, two kinds of functionalized graphene, hydroxylated graphene (GOH) and carboxylated graphene (GCOOH), were dispersed into a mixture of ethylene glycol (EG) and water (1:1 mass ratio), at the same loadings. It is found that, although the obtained GOH nanofluid exhibits a slight lower zeta potential than the GCOOH one, its optical absorption property is obviously higher. Consequently, GOH was employed to prepare the EG-water based nanofluids at different loadings, followed by the investigations on their optical absorption and thermophysical properties, photo-thermal conversion performance, and dispersion stability. It is shown that, at a loading as low as 0.007 wt%, the transmittance of the corresponding GOH/water-EG nanofluid is reduced to zero, and its extinction coefficient is 100 times higher than that of the base fluid. Under the illumination of 1000 W/m2, the 0.007 wt% GOH/EG-water nanofluid can reach a high final temperature of 55 °C. More significantly, the zeta potential of the 0.007 wt% GOH/EG-water nanofluid increases with temperature and reaches 47.63 mV at 60 ℃, suggesting its good dispersion stability at the elevated temperatures. These good characteristics of the GOH/EG-water nanofluid make it a very promising working fluid for a low temperature DASC.

Comparing Forced-Air to Resistive-Polymer Warming for Perioperative Temperature Management: A Retrospective Study

Compare perioperative temperature management between forced-air warming (FAW) and resistive-polymer heating blankets (RHBs). A retrospective, quasi-experimental study. Retrospective data analysis of nonspine orthopedic cases (N=426) over a one-year period including FAW (n=119) and RHBs (n=307). FAW was associated with a significantly higher final intraoperative temperature (P=.001, d=0.46) than the RHB. The incidence of hypothermia was not found to be significantly different at the end (P=.102) or anytime throughout surgery (P=.270). Of all patients who started hypothermic, the FAW group had a lower incidence of hypothermia at the end of surgery (P=.023). FAW was associated with higher final temperatures and a greater number of normothermic patients than RHBs. However, no causal relationship between a warming device and hypothermia incidence should be assumed.

Activation of homogeneous precursors for formation of uniform and refined α precipitates in a high-strength β-Ti alloy

The influence of heating rates and interrupted aging treatments on α precipitation in the β-quenched Ti-6Cr-5Mo-5V-4Al alloy has been investigated. Microstructure observations reveal that slow heating rates and low temperature pre-aging produce much refined and uniform distributions of intragranular α precipitates in comparison to aging using fast heating rates at a high temperature only. For interrupted aging treatments, the nucleation rate and refinement of α are gradually enhanced with increasing pre-aging time, but this is dependent on the final aging temperature: at high final aging temperatures, the distribution of α precipitates is similar to single aging at the same temperature. The kinetics of phase transformation was analyzed by thermal mechanical analysis (TMA) under the framework of the Johnson–Mehl–Avrami (JMA) theory. Coupled with microstructural observations, it is suggested that epitaxial growth of pre-existing α phase formed during heating to the aging temperature is the governing mechanism under slow heating rate conditions, while for interrupted aging treatments, the mechanism for intergranular α precipitation is consistent with that of fast heating rate single temperature aging treatments. For interrupted aging, the formation of uniform and refined α precipitates essentially relies on activation of homogeneous precursors associated with chemical partitioning and structural modulation which provide a strong driving force for nucleation of α.

Slow pyrolysis of coffee husk briquettes: Characterization of the solid and liquid fractions

The objective of this study was to investigate the kinetics of the biomass and to determine the influence of temperature on the distribution and quality of the products of slow pyrolysis. Coffee husk briquettes were produced by densification and subsequently subjected to slow pyrolysis at different final temperatures of 623 K, 673 K and 723 K at a heating rate of 0.5 °C/min. The results of the TGA showed that the pyrolysis of coffee husks occurred mainly at temperatures between 400 K and 700 K. The activation energy values ranged from 104.90 kJ/mol to 345.2 kJ/mol for the Friedman model and from 70.4 kJ/mol to 288.8 kJ/mol for the FWO model. In the composition of the bio-oil, at higher pyrolysis temperatures, there was a greater production of phenolic compounds and nitrogen compounds. Lower temperatures promoted the greater formation of hydrocarbons and acetic acid. The energy content of the biochar did not differ with the increasing temperature, but the fixed carbon was slightly higher at 723 K. It was concluded that the TGA provided information on the kinetics of the coffee husk pyrolysis, making it possible to improve the conversion process of this waste into products. Both isoconversional models were effective in estimating the Ea of the pyrolysis process with good accuracy. High final pyrolysis temperatures improve the quality of bio-oil, producing bio-oil with smaller amounts of acidic compounds, and this bio-oil is desirable for use as fuels. In addition, the bio-oil contains numerous chemical compounds that can be extracted and used in value-added chemical products.

Seasonal Plasticity in Junonia coenia (Nymphalidae): Linking Wing Color, Temperature Dynamics, and Behavior

The common buckeye, Junonia coenia (Hubner), is a North American nymphalid that shows seasonal wing color plasticity. Throughout much of its range the ventral hindwings are tan in the spring and summer and dark red in autumn. Although this species has long been used as a model to study the physiology and genetics of plasticity, the function of its seasonal color variation is still largely unknown. Here we investigate the effect of buckeye wing color on wing and body temperature and ask to what extent seasonal plasticity is associated with behavioral differences. By using real time infrared imaging of different seasonal morphs from a laboratory colony of North Carolina J. coenia, we observed that red autumnal butterflies warm up faster and reach higher final temperatures than tan summer butterflies. Furthermore, behavioral trials at field sites revealed that red butterflies are less physically active than tan butterflies. Based on our findings, we propose that the dark red wing coloration of autumn morphs could be useful for helping individuals reach higher body temperatures faster while basking on colder days. We also speculate that lower activity levels of autumnal butterflies may help conserve energy.