Arrhenius Method Research Articles

Experimental study on the mechanism of associated gas generation by heavy oil aquathermolysis and thermal cracking during steam injection

Previously, we proposed an innovative method for heavy oil recovery known as the ISSG-SAGD (in-situ solvent generation enhanced steam assisted gravity drainage) technique. This technology can improve heavy oil recovery efficiency, reduce steam consumption, and mitigate acid gas emissions. However, the reaction kinetic model used in numerical simulation was derived from literature reports and reasonable assumptions, lacking experimental validation. This study addresses this gap by conducting a series of experiments to investigate the mechanism of associated gas generation under steam injection conditions. We differentiated the reaction temperature window of aquathermolysis and thermal cracking based on the quantity and composition of the associated gas generated. The study revealed that aquathermolysis, occurring at 240–280℃, produces a small amount of associated gas (gasification degree of 0.32 %), predominantly CO2 (about 68 %). In contrast, thermal cracking, occurring at temperatures up to 380℃, significantly increases gas generation (gasification degree of 14.33 %), with light hydrocarbons (C1–5) constituting about 80 % of the gas produced. The reaction rate was found to be proportional to the reaction temperature and time. The SARA analysis showed that saturates and aromatics content increased, while resins and asphaltenes decreased after both reactions. A kinetic model for associated gas generation was established, and kinetic parameters such as activation energies and frequency factors were derived using the Arrhenius method. For example, the activation energy for CO2 generation increased from 18.19 kJ/mol during aquathermolysis to 147.58 kJ/mol during thermal cracking. This study provides a comprehensive understanding of the associated gas generation mechanisms and characteristics under steam injection, supporting the feasibility and potential application of the ISSG-SAGD technique in heavy oil recovery.

Estimation of kinetic and thermodynamic parameters during thermal decomposition of raw, boiled, and torrefied banana peel through arrhenius and CR methods

The objective of the present manuscript was to investigate the bioenergy generation potential of banana peel as solid or liquid biofuel, by examining physicochemical, kinetic, as well as thermodynamic parameters. Raw banana peel, boiled banana peel, and torrefied banana peel were subjected to a thermal decomposition environment. BBP was prepared by boiling RBP in a hot plate at 120 °C using 600 rpm, for 150 min. Besides, RBP was torrefied at 225 °C (nitrogen atmosphere), at 15 °C/min and a residence time of 30 min, to prepare TBP. Pyrolysis of all three materials was carried out at 10 and 15 °C /min using thermogravimetric analysis. The kinetic and thermodynamic parameters were evaluated using Arrhenius and CR methods. The overall activation energy at 15 °C/min was 107.04, 106.88 and 74.85 kJ/mol, for RBP, BBP, and TBP, respectively.

Investigation of structural, dielectric and optical properties of the (Bi0.5La0.5Fe)0.5(Bi0.5Na0.5Ti)0.5O3perovskite for some electronic devices

This paper outlines the investigation of structural, dielectric, complex impedance and optical properties of lanthanum-modified (Bi[Formula: see text]La[Formula: see text]Fe)[Formula: see text](Bi[Formula: see text]Na[Formula: see text]Ti)[Formula: see text]O3 (BLF–BNT) single perovskite oxide synthesized by conventional solid-state reaction method. From Rietveld refinement, the crystal structure of the BLF–BNT ceramic has confirmed a tetragonal and the estimated average crystallite size is found to be 43.6[Formula: see text]nm. The dielectric properties of the La-doped BLF–BNT ceramic reveal the presence of Maxwell–Wagner-type dielectric dispersion. This suggests the occurrence of charge accumulation at grain boundaries and interfaces within the material. The complex impedance and complex electric modulus studies were employed to gain insight into the microscopic dielectric relaxations and conduction processes of the material. The electric modulus spectroscopy reveals the existence of nonDebye-type relaxation processes, including localized and long-range relaxation processes. The Nyquist and Cole–Cole plots show the semiconducting nature of the BLF–BNT ceramic. With the help of the Arrhenius method based on the imaginary portion of the electrical impedance and modulus, activation energies and relaxation times have been estimated. These parameters contribute to a deeper understanding of the electrical properties and conduction mechanisms within the material. Further, Raman spectroscopy, a nondestructive chemical analysis technique, was conducted to confirm the composition and structural integrity of the proposed system through its atomic vibrations. Also, the bandgap energy of the material has been estimated using Tauc’s relation and is found to be 1.69[Formula: see text]eV. This signifies that the BLF–BNT ceramic possesses a suitable bandgap for certain device applications, making it a promising candidate in various technological fields. Moreover, the overall comprehensive study of the proposed ceramic provides valuable insight and opens new possibilities for its potential applications in various electronic devices.

Innovation of Traditional Culinary Lemuru Fish with Yellow Spices Using Canning Technology at Fish Canning Teaching Factory Politeknik Negeri Jember

Canned fish is one of TEFA Fish Canning’s products that has potential in Indonesia, however consumption of canned fish in Indonesia is still relatively low than the other countries. One of the problems that often occurs with canned fish products from TEFA Fish Canning is the lack of product variations are limited only to tomato and chili sauce. One of the canned fish that has the potential to be developed is lemuru fish with yellow spices in cans by combining canning technology and a touch of typical Indonesian processing in yellow spices. The objectives of the research were (a) to see the formulation and nutritional value of yellow spiced lemuru fish products in canned packaging, (b) to assess the product’s sensory quality to determine market acceptance, and (c) to determine the best yellow spiced lemuru fish formulation using the Multiple Attribute method. This research was carried out using a Completely Randomized Design (CRD) with 5 formulations of yellow spiced lemuru fish being tested including lemuru fish with pesmol seasoning, lemuru fish with rujak seasoning, lemuru woku fish, lemuru fish with rujak basil seasoning, and lemuru fish with pesmol basil. The parameters tested include physical, chemical and organoleptic characteristics. Parameters for determining the best treatment include color (L*, a*, & b*), pH, salinity, hedonic test (aroma, color, taste, texture, & overall) and hedonic quality test (aroma, color, taste, texture, & whole). The test results show that canned yellow spiced lemuru fish with formulation 3, namely woku lemuru fish, is the sample with the best parameter attributes, namely with values L* = 50.88, a* = 29.03, b* = 54.23, pH = 6, 32, salinity = 1.09, hedonic color = 4.24, aroma = 3.92, taste = 3.68, texture = 3.84, and overall = 4.20. The final results will show yellow spiced lemuru fish as a new canned fish product at TEFA Fish Canning with a recommended shelf life that has been tested using Arrhenius Method. Based on the Arrhenius test, canned lemuru fish with yellow spices can be stored at 30°C for 224 days. The novelty brought about in this research is the formulation of yellow spiced lemuru fish products in cans which can be used as a new product for TEFA Fish Canning as a solution to the problem of minimal product variety.

Preparation of Astragalus membranaceus–cranberry biscuits and the evaluation of physicochemical properties and antioxidant activity

SummaryAstragalus membranaceus, as a medicinal and edible product, contains a variety of active ingredients. The cranberry powder is rich in polyphenol, dietary fibre, vitamins and mineral. In this study, biscuits were prepared by enrichment with Astragalus membranaceus and cranberry powder. The basic nutrients, physicochemical indexes, odour characteristics, antioxidant properties and shelf life prediction of the Astragalus membranaceus–cranberry biscuits (AMCB) were evaluated and compared with commercial biscuits. Overall, the biscuits with the addition of Astragalus membranaceus and cranberry had low water content and high protein content of 8.3 g/100 g. The antioxidant properties of AMCB were analysed by DPPH radical scavenging activity and hydroxyl radical scavenging activity, and the results demonstrated that AMCB possessed higher antioxidant activity than cranberry biscuits (CRB) and control biscuits (CB). The water content and peroxide value index were used to predict the shelf life by accelerated test. According to the Arrhenius method, the shelf life of AMCB was about 112 days. The results showed that the addition of 23% Astragalus membranaceus and cranberry powder led to improved nutritional value, antioxidant properties and sensory characteristics of the biscuits.

Thermoresponsive Behavior of Binary Waxes

AbstractIn this study, we investigated the thermoresponsive behavior of two different binary wax compositions of commercially available natural candles. The chemical nature of carbon bonds in the fatty acid chains of the natural wax component effectuate a different hygroscopic behavior, as confirmed by NMR analysis. The phase transitions of polymorphic stearin‐rapeseed and stearin‐coconut wax composites were tracked by DSC‐TGA and VT‐XRD. The reduction in the eutectic temperatures of wax composites during the second heating cycles of DSC measurements was correlated with the length of fatty acid chains in rapeseed and coconut waxes, as well as their co‐crystallization kinetics with stearin. Mechanical and hygroscopic behavior of the binary waxes were examined at elevated temperatures between 23 °C and 45 °C using QCM‐D. Voigt viscoelastic model was employed to reveal the soft and rigid textures of wax composites. The hydrophilic behavior of the rapeseed wax composite changed to hydrophobic when the co‐crystallized and individual stearin melted above 35 °C. Activation energies required for melting wax crystals were calculated to be 51±3 kJ mol−1 for pure rapeseed wax, 373 kJ mol−1 for co‐crystallized rapeseed and stearin waxes, and 244 kJ mol−1 for co‐crystallized coconut and stearin waxes, using Arrhenius method with the QCM‐D data.

Sensory Attribute Properties and Shelf Life Of Chicken-Herbal Essence Functional Drinks

Chicken-herbal essence, a nutritionally rich functional beverage boasting elevated levels of proteins and amino acids, is renowned for its health-promoting attributes, notably its positive effects on lactation. Comprising an amalgamation of free-range chicken, red ginger, brown sugar, honey, sesame oil, nutmeg, salt, and water, this elixir undergoes a discernible deterioration in quality when subjected to prolonged storage. Consequently, imperative research endeavors are undertaken to elucidate the temporal constraints of storage for this esteemed functional drink. The present study is oriented towards gauging the degradation in quality and prognosticating the shelf life of chicken-herbal essence when exposed to three distinct temperatures—refrigerator temperature (10°C), ambient room temperature (25-27°C), and an elevated temperature (35°C)—utilizing the Arrhenius method as the analytical framework. Conducted over a rigorously observed four-week duration at both the Djuanda University Food Laboratory and the LPPOM MUI Laboratory, this study systematically examines diverse parameters, including pH levels, total dissolved solids, total plate count (TPC), and a comprehensive sensory evaluation. The pH testing, conducted employing a precision pH meter, yields a range of 4.676 – 5.074, while total dissolved solids ranged from 27,100 – 27,450 Brix; total plate count ranged from 0 – 20 CFU/mL. In the sensory test, samples at three temperatures were withdrawn upon panelists' arrival. Generally, refrigerated and room temperature storage showed higher acceptability than higher temperature (35°C) storage. Shelf life estimation indicated that refrigerated storage (10°C) extended to 53 days, surpassing the other temperatures.

Estimation of shelf life for Ready-To-Eat sardines (RTE) using the Accelerated Shelf-Life Testing (ASLT) method

Ready-to-eat sardines (RTE) are ready-to-eat foods designed to satisfy the needs of people who don’t have time to cook. In order to maintain the quality of RTE products and have a longer shelf life, efforts should be made to maintain the quality of RTE products, one of which is the use of cold storage methods and packaging. The purpose of this study was to estimate the shelf life of RTE sardines using the accelerated method combined with the Arrhenius method. This study employs a completely randomised Design with two factors: packaging type (vacuum and non-vacuum packaging) and storage temperature (cold storage and freezing temperature). The parameters tested in this research include TPC (total plate count), organoleptic properties, fat content, and protein content. The estimated shelf life of ready-to-eat sardines (RTE) in this study shows that RTE fish has a shelf life of up to 558.96 days if stored at a freezing temperature and vacuum packed, and 313.29 days if stored at a refrigerated temperature and vacuum packed. While ready-to-eat sardines (RTE) have a shelf life if stored using pouch packaging of 514.83 days at freezing and 2945.13 days at refrigerated temperatures with the Arrhenius equation obtained, namely ln k = (13.436 – 3034.6) (1/T).

HNBR and NBR gasket rubbers for plate heat exchangers: Thermo‐oxidative aging and service lifetime prediction

AbstractAmong several available rubbers used in gaskets for plate heat exchangers, the selection of the appropriate material for each operation window is crucial. This work evaluated nitrile butadiene rubber (NBR) and hydrogenated butadiene rubber (HNBR) gaskets aged at high temperatures for up to 60 days. The properties assessed of compression set (CS), hardness, and cross‐link density demonstrated superior degradation rates for the NBR specimens. Fourier transform infrared analysis showed that the hydrogenation process predominantly affected CC double bonds. Compress stress relaxation highlighted the impact of aging on the counterforce of rubber over time. Furthermore, indentation modulus profile analysis showed heterogeneous degradation for both materials at 140°C for NBR and 170°C for HNBR. The end‐of‐life criteria of 79% CS for both materials were determined through sealing tests of the aged samples. The service lifetime prediction, using the time–temperature superposition and Arrhenius methods through the CS evolution curves, demonstrated a higher degradation resistance of HNBR gaskets, that have a superior service lifetime of at least 3.5 times at 80°C concerning those of NBR, proving a superior behavior for the hydrogenated elastomer. In addition, the evaluation of the lifetime prediction enables the verification of which rubber gasket is recommended for each operational condition in terms of material cost, service lifetime, and maintenance costs.

MODEL KINETIKA KEKERASAN GULA CETAK TEBU DENGAN PENAMBAHAN BUBUK KAYU MANIS SELAMA PENYIMPANAN

The sugar cane juice produced through evaporation is processed into molded cane sugar. Adding cinnamon powder to cane sugar provides additional benefits for body health. One of the quality criteria for molded cane sugar is its hardness. The hardness value of printed cane sugar changes during storage; the sugar becomes softer and less complicated. Reaction kinetics can be used to observe changes in the hardness of printed cane sugar. The Arrhenius method was used in this research to determine how adding cinnamon powder affects the quality of molded cane sugar. This research used molded cane sugar with two concentrations of cinnamon powder, namely 0% and 0.255%. The sugar was then stored at three different temperatures, seven °C, 27 °C, and 45 °C, over 30 days, with daily observations. Kinetic analysis of molded cane sugar shows that when cinnamon powder is added, the quality decreases more quickly compared to control molded cane sugar, which has a k value of 0.3378 N/cm2/day at a temperature of 7°C, 0.4629 N/cm2/day at a temperature of 27°C, and 2.2728 N/cm2/day at a temperature of 27°C. Compared with storage temperatures of 27°C and 45°C, a temperature of 7°C showed a slower decline in the quality of molded cane sugar.

Environmental quality assessment of soil as a component of green spaces in parks of the megalopolis

Intensive land degradation occurs under conditions of accelerated urbanization; it is strongly associated with the loss of soil natural capital, primarily animals, plant cover, and biological diversity in general. The creation and functioning of parks, in particular green spaces, in the urbanized areas is an effective mechanism for optimizing the ecological situation within the cities and preventing desertification. The soils of parks are an integral component of green infrastructure; they determine the conditions for the growth and development of both individual plants and green spaces as a whole. The soil buffering capacity actively participates in the mechanisms of implementation of the development and stabilization of soil fertility potentials. The buffering capacity determines the proportion of the soil potential that controls the processes of immobilization (deposition) and mobilization (release, loss) of a particular element of fertility: first of all, mineral nutrients for plant growth, productive moisture, thermal energy in soil, gas composition of soil air, and acidity. We collected soil samples beneath the crowns of trees growing in the territory of the Taras Shevchenko Central Culture and Leisure Park, as one of the largest parks in the city of Dnipro (Ukraine). The soil samples were collected in order to assess the soil acid-base (pH) buffering capacity (pHBC) and determine the direction of microbiological processes in urban soils of the park area afforested with stands from such introduced tree species as green ash (Fraxinus pennsylvanica), black locust (Robinia pseudoacacia), northern red oak (Quercus rubra), tree of heaven (Ailanthus altissima), Kentucky coffee tree (Gymnocladus dioica), and box elder (Acer negundo). The acid-base buffering capacity of the urban soil was determined using the Arrhenius method and estimated according to the buffering area within the acid-base range, calculated using the Simpson formula. Direction of microbial processes in the soil was determined according to the indexes of mineralization-immobilization, pedotrophicity, and oligotrophicity. The output was processed using statistical methods (arithmetic mean and standard deviation were calculated; the difference in the means was found according to the Tukey’s comparison test; interdependencies were determined by linear correlation). We have found significant, strong positive correlations between the pH level of urban soils in the rhizosphere area of the introduced species of park dendroflora and the buffering area within the acid and acid-base (total) range of external influence, as well as a strong negative correlation between pH and buffering area in the alkaline range of external influence. We identified weak mineralization signs according to the ratio of functional groups of microbiota in the studied sites forested with Fraxinus pennsylvanica and Acer negundo.

Assessment of the soil buffer capacity in the green plantings of the megalopolis parks

Land degradation poses a serious challenge to food security, livelihood sustainability, ecosystem services and biodiversity conservation, while inefficient land management leads to widespread loss of soil biodiversity. The soil buffer capacity is actively involved in the mechanisms of implementing such an ecosystem service as the development and stabilization of soil fertility. Buffering determines the share of the soil potential that determines the processes of immobilization (deposition) and mobilization (release, loss) of a particular element of fertility – first of all, mineral nutrients required by plants, productive moisture, thermal energy of the soil, gas composition of soil air, acidity. The soils in parks on the territory of megacities are an integral component of them determining the conditions for the growth and development of green spaces. We assessed the acid-base (pH) buffer capacity of urban areas in a park area covered with tree stands of such introduced tree species as horse chestnut (Aesculus hippocastanum), sugar maple (Acer saccharum), small-leaved elm (Ulmus parvifolia), common hackberry (Celtis occidentalis), honey locust (Gleditsia triacanthos) and Japanese pagoda tree (Styphnolobium japonicum) growing on the territory of the T. G. Shevchenko Park (Dnipro city, Ukraine). Soil samples were collected under the crowns of these tree species. The acid-base buffering capacity of urban soils was determined by the Arrhenius method, which includes adding certain volumes of acid and alkaline components to the sample, and further calculating the buffering area within acid and base intervals. Buffering areas were calculated using the Simpson formula. The results were processed with statistical methods (arithmetic mean and standard deviation were calculated, and the difference in means was found according to the Tukey's comparison test). Initially the samples of the studied soils were found to have mostly a slightly alkaline reaction of the soil solution. Within the acid range of external influences, the buffer capacity of urban soils under introduced tree species was determined to establish the following descending series: horse chestnut, common hackberry, small-leaved elm, honey locust, Japanese pagoda tree, sugar maple. The same series was established for the total acid-base buffering capacity. The results show the greater acid-base buffer capacity of soils sampled under horse chestnut, common hackberry, small-leaved elm and honey locust trees, and therefore these soils were resistant to degradation compared to the soils sampled under Japanese pagoda tree and sweet maple. The environment-forming role of introduced tree species in the implementation of buffer properties of urban soils in the park on the megalopolis territory can be assumed.

Accelerated shelf life determination of corn snack bars.

Corn snack bars are a product made from corn extrudate and additional ingredients in the form of sorghum flour and can be consumed as a nutritious snack. The shelf life of snack bar products needs to be known to ensure product quality reaches consumers. This study aims to determine the shelf life changes in critical parameters during storage using the accelerated shelf life testing Arrhenius method. Tests on the estimation of shelf life with the Arrhenius method were carried out at 3 different storage temperatures (10°C, 30°C, and 47°C) for 35 days with an observation time of every 7 days. The shelf life of corn snack bars was tested using parameters of quality changes such as water content, texture hardness, and springiness. Based on the results obtained, the final shelf life of the corn snack bar is determined by the crispness parameter; shelf life at 10°C is 233 days, at 30°C is 111 days, and at 47°C is 363 days.

The shelf life of smoked catfish coated with edible coating chitosan with an addition horticultural product (red ginger and red galangal) essential oil using the acceleration method

This study aimed to calculate the shelf life of smoked catfish coated with edible coating chitosan, red ginger, and red galangal essential oil. The smoked catfish was kept for 30 days at three different temperatures, i.e., 30, 35, and 40°C, and the sensory evaluations of rancidity and thiobarbituric acid (TBA) values of the smoked catfish served as the criteria monitored during the storage process. The obtained data were analyzed using linear regression to show the relations between storage time and the measured variables. Furthermore, the Arrhenius method was used to calculate the shelf life of smoked catfish to compare the decline in the quality of the smoked catfish. The result showed that the smoked catfish coated with edible coating chitosan and red ginger had a shelf life of 32.90 days at a temperature of 30°C with the regression equation y = 2529.6x + 4.3342, and the smoked catfish coated with edible coating chitosan, red ginger, and red galangal essential oil was 37.10 with the regression equation y = -3085.1x + 6.039. For the next research, it is necessary to research on the effect of red galangal essential oil on the shelf life of smoked catfish.

Oxidation Kinetics Analysis of Crude Oils with Different Viscosities

In order to compare the oxidation kinetics parameters of crude oils with different properties in the process of crude oil oxidation, six different crude oil samples were selected to analyze the oxidation characteristics of crude oils with different properties. In order to study the oxidation of crude oil, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) synchronous analyzer were used for crude oil in the oxygen environment between 25 °C and 900 °C at a heating rate of 20 °C/min. The experimental results were based on crude oil oxidation using TGA and DTG experimental data to evaluate the oxidation mechanism of different crude oils, so as to better understand the situation in the oxidation reaction process. At the same time, the oxidation stage of crude oil was divided according to DSC data. Arrhenius method was used to analyze the oxidation kinetic parameters of crude oils with different properties, and the activation energies and pre-exponential factors of different crude oils were calculated. The experimental results show that the oxidation stage of crude oil can be divided into three stages: low-temperature oxidation, fuel deposition, and high-temperature oxidation. The low-temperature oxidation reaction begins at 280 °C, and the high-temperature oxidation reaction occurs at 400 °C. The low-temperature oxidation activation energy of an oil sample is 39.73–77.74 kJ/mol. The activation energy of the high-temperature oxidation is in the range of 106.27–264.47 kJ/mol. The activation energy of crude oil in the low-temperature oxidation stage increases with the increase of crude oil viscosity and decreases with the increase of crude oil viscosity in the high-temperature oxidation stage. Therefore, during the high-temperature oxidation stage, high-viscosity crude oil is more prone to reactions.

Improved hydrogen storage thermodynamics and kinetics of La–Ce–Mg–Ni alloy by ball milling

Reducing particle size and modifying surface state by ball milling are recognized as a useful method to improve the hydrogen absorption kinetics of Mg-based alloys. In order to obtain amorphous and nanocrystalline structures, ball milling was used to process the as-cast La7Ce3Mg80Ni10 alloy ingot. The effects of ball milling time (5–30 h) on the structures and the thermodynamics and kinetics of hydrogen absorption/desorption of the as-milled alloys were studied. The XRD, SEM and TEM were applied to investigate the structure of the alloys. The Sievert apparatus, DSC and TGA were applied to study the isothermal and non-isothermal properties of hydrogen absorption/desorption. The Arrhenius and Kissinger methods were used to calculate the activation energy of hydrogen desorption. The results indicate that the 10 h-milled alloy has the optimal activation performance and hydrogen absorption/desorption kinetics. Prolonging or shortening the ball milling time results in the impaired hydrogen storage properties. The 10 h-milled alloy in fully activation state can absorb 4 wt% H2 in 80 s at 473 K and 3 MPa, and it can desorb 3 wt% H2 in 191 s at 573 K and 1 × 10−4 MPa. The hydrogen desorption enthalpy (ΔH) of the 10 h-milled alloy is 74.21 kJ/mol. Moreover, the 10 h-milled alloy has the smallest apparent activation energy for hydrogen desorption (62.9 kJ/mol), which is the reason why it has the optimal hydrogen storage properties.

Isothermal decomposition of AlH3/hydrogen absorbents

In this article, the isothermal decomposition dynamics research instrument was used to investigate the interaction between three hydrogen absorbents and AlH3, including C60, C70, and 1,4-bis (phenylethynyl) benzene (DEB). The gas volumes emitted by AlH3, AlH3/C60, AlH3/C70, and AlH3/DEB during the 48 h vacuum stability experiment were 2.85, 2.41, 1.92 and 2.02 mL/g, respectively. The isothermal thermal breakdown of the three materials was investigated simultaneously at 333–393 K. The isothermal thermal decomposition kinetic parameters of AlH3/C60, AlH3/C70, and AlH3/DEB were determined using the Arrhenius and model-fitting method by using the pressure–time curve of the decomposition and release gas of the mixed sample of AlH3 and three hydrogen absorbents. AlH3/C60, AlH3/C70, and AlH3/DEB had activation energies of 118.2, 116.9, and 116.8 kJ·mol−1, respectively and pre-exponential factors of 20.49, 20.16, and 20.19, respectively. By using XRD and TEM, the thermal breakdown products were examined.

Thermal decomposition characteristics and study of the reaction kinetics of tea-waste

This study aimed to investigate waste-tea’s pyrolysis kinetics and thermodynamics to assess its potential for thermochemical processes. In this study, three primary samples of tea-waste are prepared for investigation: raw, torrefied at 200 °C, and torrefied at 600 °C. Under a nitrogen environment, thermogravimetric analyses (TGA) were conducted at seven heating rates (10, 15, 20, 25, 30, 35, and 40 °C/min) to investigate the effect of heating rates on the kinetic parameters at temperatures ranging from 27 to 1000 °C. Using seven heating rates was beneficial to take advantage of multiple heating rates techniques alongside single heating rate techniques. These heating rates were combined, forming four heating rate groups (HRG). The pyrolysis kinetic parameters are determined using two model-fit-methods, direct Arrhenius and Coats-Redfern methods, and two model-free methods, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. Thermodynamic data comprising ΔH, ΔG, and ΔS are addressed. The X-ray fluorescence (XRF) and Fourier transform infrared (FTIR) spectrum are used to assess the presence of natural minerals in tea-waste. The results indicated that the tea-waste material has the potential to produce syngas. The torrefaction process at 600 °C shows a 53% increase in the energy content compared to the raw biomass. The Coats-Redfern is shown to be more reliable than the direct Arrhenius method. The activation energy (Ea) witnesses rising with the heating rate (β) from Ea = 55.27 kJ mol−1 at β = 10 °C min−1 to 60.04 kJ mol−1 at β = 40 °C min−1 for raw tea-waste using Coats-Redfern method. For model-free approaches, the minimum activation energy values of the raw tea-waste samples are 82 kJ/mol for FWO and 78 kJ/mol for KAS, whereas the peak values are 420 kJ/mol for KAS and 411 kJ/mol for FWO. A comparison of the effect of heating rate groups for FWO method in raw material case indicated that HRG1 has the maximum activation energy average value. The resulting values of HRG1, HRG2, HRG3, and HRG4 were 269 kJ/mol, 145 kJ/mol, 174 kJ/mol, and 202 kJ/mol, respectively.

Cobalt ferrite nanoparticles anchored on reduced graphene oxide nanoribbons (0D/1D CoFe2O4/rGONRs) as an efficient catalyst for hydrogen generation via NaBH4 hydrolysis

For better performance of nanoparticles as the heterogeneous catalyst, various materials with a large surface area have been introduced as the substrate. Herein, CoFe2O4 nanoparticles were anchored on carbon nanotubes (CoFe2O4/CNTs) and graphene nanoribbons (CoFe2O4/GONRs) to investigate the influence of substrate in the catalytic performance. These nanocomposites were evaluated in a NaBH4 hydrolysis reaction to produce hydrogen. The results showed that the highest hydrogen volume occurs in the presence of CoFe2O4/GONRs nanocatalyst. Abundant oxygen-based functional groups at the edges of GONRs offered excellent sites for CoFe2O4 nanoparticles and improved catalytic performance. Under optimum conditions (2.0 wt% of NaBH4, 15 mg of catalyst, 2.0 wt% of NaOH), the hydrogen generation rate was found to be 3.7 L g-1min−1 at 35 °C. The activation energy was calculated using the Arrhenius method, equivalent to 31.4 kJ mol−1. Therefore, CoFe2O4/GONRs catalyst can be a novel and efficient candidate for hydrogen production as a clean fuel.

Synergistic effect of silica nanoparticles assisted by rosemary powder in the stabilization of styrene-isoprene-styrene triblock copolymer

The synergistic efficiency in the improvement of thermal and radiation stabilities of polymer substrate (styrene-isoprene-styrene triblock copolymer) is studied by isothermal and nonisothermal chemiluminescence, when silica nanoparticles loaded in various proportions (1, 2, and 3 wt%) are coupled with rosemary in the dropping down the degradation rate. The measurements of chemiluminescence emission intensities at various degradation degrees obtained by accelerated ageing with γ-radiation provide the evidences for a synergistic action of n-silica nanoparticles/rosemary extract upon the stability of polymer matrix. The main kinetic parameter, oxidation induction time (OIT), which describes the stabilization efficiency of additives by the hindering of oxidation presents illustrative values for the co-operation factors between the two prevention components. The synergistic effect is evident: the OIT of couple action is much higher than the values that characterize component activities. This feature has much higher values than unity. The contribution of this inorganic/organic antioxidant couple is discussed based on the activation energy values calculated by Arrhenius method. The effects of silica nanoparticles on the delay of degradation is also analyzed by means of nonisothermal chemiluminescence measurements, which prove the increase of protection activity when the silica loading is enhanced from 1 to 3 wt%. The applications of this stabilization couple may be found in the areas of food handling, pharmaceutics, medical wear, dentistry, nuclear sealing, commodities, and many suitable others.