Min Heating Rate Research Articles

Experimental investigation on thermal conductivity and thermal degredation of Honge oil methyl ester with B-20 blend.

Honge oil methyl ester (HOME) with B-20 blend is considered to examine thermal con- ductivity and thermal degredation of the biodiesel. Transient hot wire method is adopted to determine thermal conductivity of the samples.Heat source is clubbed with C-DAQ and LAB-VIEW software is utilized to record temperature and time. Following Sastry’s power law model, an improved emperical relation is developed for thermal conductivity of HOME with B-20 blend. Thermogravitometry (TG-DTG) analysis is performed under atmospheric condi- tions with 10°C/min heating rate of pure air flow.Diesel is exhibited one mass loss event from 55–334°C, whereas two mass loss event in case of biodiesel. Maximum decoposition tem- perature noticed for diesel,HOME andB-20 blend are 195°C, 227°C and 175°C respectively. Complete mass degradation takes place for diesel and HOME at 498°C, in case of HOME with B-20 blend complete mass degradation occurred at 377°C.

Biofuels production from pine needles via pyrolysis: Process parameters modeling and optimization through combined RSM and ANN based approach

The current study determined the pyrolysis potential of pine needles with the aim to assess the influence of process parameters (namely temperature, heating rate and inert gas flow rate) along with their modeling and optimization through combination of response surface methodology (RSM) and artificial neural network (ANN) technique. Pyrolysis process output was predicted by ANN, while interaction and significance/insignificance along with optimization of process parameters was determined by RSM. A combined approach was employed to accomplish the individual limitations of both the modeling methods. R2 close to 1 and low error demonstrates the viability of the developed models. Results showed comparatively higher R2 and lower MSE value for ANN model, thereby elucidating superior capability of ANN for predicting process yield over RSM modeling; while RSM accurately predicted the process parameters interaction and significance. The study revealed that such a combinational approach has the better ability to model the pine needle pyrolysis process compared to the individual ones. Temperature had been determined as the most predominant variable influencing the yield of the products. Optimized condition had been predicted at 552.06 °C temperature, 50 °C/min heating rate and 164.40 mL/min inert flow rate by yielding maximum bio-oil as 51.11 and 51.70% from RSM and ANN modeling, respectively. Detailed characterization advocates high end-use of all the three products. GC–MS and FTIR techniques predicted that bio-oil was composed of different organic compounds and can be utilized in place of hydrocarbon fuels after certain upgradation processes and can also be extracted into various chemicals. Characterization of biochar and non-condensable gases also demonstrate their potential application as fuel and in several other fields. The study revealed that pine needles can be effectively employed for the production of bioenergy precursors.

Combustion Characteristics of Coal, Petroleum Coke, Biomass, and Their Ternary Blends

Abstract This work presents the combustion characteristics of coal, petroleum coke (PC), rice straw (RS), mustard cake (MC), and their blends to assess the applicability of blended fuel for thermal power generation. Characterization results show that PC has the highest gross calorific value (GCV) (35,990 kJ/kg) to improve the overall energy density of the blend significantly. Higher volatile matter (VM) present in RS and MC improved the ignition behavior and combustion efficiency of the blend. For 10 °C/min heating rate at 350 °C, with the increase in RS in blends from 10% to 30%, combustion efficiency increased from 12.85% to 32.66%. Synergistic analysis signifies that higher biomass content enhances blends’ combustion characteristics through catalytic effects of alkali oxides present in RS/MC. Thermodynamic analysis (ΔH, ΔG, and ΔS) inferred that RS and MC combustion is easier than coal and PC. With the increase in MC in blends from 10% to 30%, ΔH decreased from 114.81 to 82.31 kJ/mol, ΔG declined from 159.33 to 122.86 kJ/mol, and ΔS improved from −63.59 to −58.14 J/mol · K, indicating blending of biomass improved the combustion.

Effect of Oxygen Functional Groups in Reduced Graphene Oxide-Coated Silk Electronic Textiles for Enhancement of NO2 Gas-Sensing Performance.

An electronic textile-based NO2 gas sensor was fabricated using commercial silk and graphene oxide (GO). It showed a fast response time and excellent sensing performance, which was simply accomplished by modifying the heat-treatment process. The heat treatment was conducted at 400 °C and different heating rates of 1, 3, and 5 °C/min. Compared with our previous research, the response time significantly decreased, from 32.5 to 3.26 min, and we found that the highest response was obtained with the sensor treated at a heating rate of 1 °C/min. To find the reason for this enhanced sensing performance, the morphology, structure, and chemical composition of the reduced GO (rGO) were investigated, depending on the thermal treatment process, using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. We also measured the temperature-dependent resistance of rGO, which was well described by the fluctuation-induced tunneling (FIT) model. These results revealed that the rGO thermally treated with 1 °C/min of heating rate had the largest amount of oxygen groups. This means that the oxygen functional groups play an important role in NO2 gas-sensing performance.

Co-pyrolysis of petroleum coke and banana leaves biomass: Kinetics, reaction mechanism, and thermodynamic analysis

Insights into thermal degradation behaviour, kinetics, reaction mechanism, possible synergism, and thermodynamic analysis of co-pyrolysis of carbonaceous materials are crucial for efficient design of co-pyrolysis reactor systems. Present study deals with comprehensive kinetics and thermodynamic investigation of co-pyrolysis of petroleum coke (PC) and banana leaves biomass (BLB) for realizing the co-pyrolysis potential. Thermogravimetric non-isothermal studies have been performed at 10, 20, and 30 °C/min heating rates. Synergistic effect between PC and BLB was determined by Devolatilization index (Di) and mass loss method. Kinetic parameters were estimated using seven model-free methods. Standard activation energy for PC + BLB blend from FWO, KAS, Starink, and Vyazovkin methods was ≈165 kJ/mol and that from Friedman and Vyazovkin advanced isoconversional methods was ≈171 kJ/mol. The frequency factor calculated for the blend from Kissinger method was found to be in the range of 106-1016s−1. Devolatilization index (Di) showed synergistic effect of blending. The data pertaining to co-pyrolysis was found to fit well with R2 (second order) and D3 (three dimensional) from Z(α) master plot. Thermodynamic parameters, viz. ΔH ≈ 163 kJ/mol and ΔG ≈ 151 kJ/mol were calculated to determine the feasibility and reactivity of the co-pyrolysis process. The results are expected to be useful in the design of petcoke and banana leaves biomass co-pyrolysis systems.

Effect of different heating rate on properties of fired brick produced from industrial waste and natural clay

Gypsum waste is generated from the wastewater treatment plant activities from chemical industry. The environmental issues and secured landfill costs caused by this waste increasing every year. Therefore, this study is an attempted to reuse gypsum waste as a substitution material for natural clay in fired brick production. This study consisted of two stages where in the first stage, fired brick were produced from natural clay and gypsum waste with substitution of clay with 5%, 10%, 15% and 20% gypsum waste. The second stage was the investigation of the experimental when the brick samples were fired at different heating rates (1 °C/min, 2 °C/min and 3 °C/min). Next, the shrinkage, dry density, water absorption and compressive strength for each sample were examined and were compared to the control brick. Based on the results, the shrinkage and water absorption increased with the addition of gypsum waste in brick samples. In contrast, the density and compressive strength values were decreased in the brick samples containing gypsum waste. The mechanical properties met the conditions prescribed in the specified standards for all the samples and the optimization result showed that up to 10% of gypsum waste incorporation into fired brick (fired at 1°C/min heating rate) had a sufficient compressive strength over 20 MPa. The reclamation of gypsum waste was proved for the fired brick production insights reducing the environmental pollution. Gypsum waste can be used as a natural clay substitution whilst fulfilling the demand for fired brick requisition.

Flash sintering and dielectric properties of K0.5Na0.5NbO3

AbstractK0.5Na0.5NbO3 (KNN) of 4‐μm average particle size was flash sintered in parallel plate capacitor configuration (PPCC) under 100 V/mm (0.8 mA/mm2 cut‐off) with 10°C/min heating rate in air. Precipitous densification occurred from Tf = 662–670°C (Tf–furnace temperature) in 60 s with 55 mW/mm3 peak power absorption at Tf = 667°C, resulting in 98% dense ceramic of < 5‐μm grains size. No grain growth was observed. A cubic grain morphology was inherited from the starting KNN powder. No sign of liquid phase formation on grain boundaries (GBs) was detected. A 147°C rise above Tf = 667°C due to Joule heating is predicted. At 25°C and 1 kHz, relative permittivity (εr) and dielectric loss (tan(δ)) are 4096 and 2.9%, respectively. From 0.1 to 100 kHz, εr and tan(δ) undergo relaxation, reaching εr = 577 and tan(δ) = 0.2% at 1000 kHz. Variation of εr with temperature revealed Amm2 → P4mm and P4mm → Pm3m transitions at ∼204°C and 409°C, respectively. As per Curie–Weiss analysis, Curie temperature and Curie–Weiss constant are θ = 375°C and C = 3.1 × 10−5°C for the P4mm → Pm3m transition, respectively. The transition is first order as Ttr > θ with a diffusiveness exponent γ = 1.04, indicating normal ferroelectric behavior. The low‐frequency dielectric relaxation is attributed to the space charge in the vicinity of GBs, which is a remnant of flash sintering. Joule heating cannot alone account for the densification in 60 s, which we substantiate within the framework of phase equilibrium and diffusion kinetics. We conjecture that oxygen vacancies start ionizing at Tf = 662°C, couple with the applied electric field via the Lorentz force, and increase their electrochemical potential, causing ultrafast densification. The effects of sample shape, size, and PPCC contributing to high sintered density are also discussed.

Formation of L10-FeNi hard magnetic material from FeNi-based amorphous alloys

L10-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe42Ni41.3Si8B4P4Cu0.7 amorphous alloy, and the L10-FeNi formation mechanism has been studied. It is found the L10-FeNi in annealed samples at 400 °C mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 60 °C lower than the measured onset temperature of the second stage with a 5 °C/min heating rate. Annealing at 400 °C after fully crystallization still caused a slight increase of coercivity, which was probably contributed by the limited transformation from other high temperature crystalline phases towards L10 phase, or the removal of B from L10 lattice and improvement of the ordering quality of L10 phase due to the reduced temperature from 520 °C to 400 °C. The first stage of crystallization has hardly direct contribution to L10-FeNi formation. Ab initio simulations show that the addition of Si or Co in L10-FeNi has the effect of enhancing the thermal stability of L10 phase without seriously deteriorating its magnetic hardness. The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects. The approaches of synthesizing L10-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.

Evaluation of oil palm fiber biochar and activated biochar for sulphur dioxide adsorption

The emission of sulphur dioxide (SO2) gas from power plants and factories to the atmosphere has been an environmental challenge globally. Thus, there is a great interest to control the SO2 gas emission economically and effectively. This study aims to use and convert abundantly available oil palm fiber (OPF) biomass into an adsorbent to adsorb SO2 gas. The preparation of OPF biochar and activated biochar was optimised using the Response Surface Methodology (RSM) based on selected parameters (i.e., pyrolysis temperature, heating rate, holding time, activation temperature, activation time and CO2 flowrate). The best adsorbent was found to be the OPF activated biochar (OPFAB) compared to OPF biochar. OPFAB prepared at 753 °C for 73 min of activation time with 497 ml/min of CO2 flow yields the best adsorption capacity (33.09 mg/g) of SO2. Meanwhile, OPF pyrolysed at 450 °C of heating temperature, 12 °C/min of heating rate and 98 min of holding time yield adsorption capacity at 18.62 mg/g. Various characterisations were performed to investigate the properties and mechanism of the SO2 adsorption process. Thermal regeneration shows the possibilities for the spent adsorbent to be recycled. The findings imply OPFAB as a promising adsorbent for SO2 adsorption.

Thermogravimetric pyrolysis of onion skins: Determination of kinetic and thermodynamic parameters for devolatilization stages using the combinations of isoconversional and master plot methods

Thermogravimetric pyrolysis of onions skins was studied thoroughly for the first time. Kinetic calculations of devolatilization stages were performed applying direct Arrhenius plot (DAP) method and combinations of isoconversional and Criado’s Z(α) master plot (CZMP) methods. The kinetic parameters calculated using combined methods were utilized successfully to reproduce the experimental kinetic curves whereas those calculated using DAP method failed in this sense. The average Ea values of isoconversional methods were between 164.0 and 172.0 kJ/mol. The CZMP method yielded multiple F-type reaction mechanisms. The simplified kinetic models of combined methods were also developed by using single reaction mechanisms deduced from multiple reaction mechanisms. The Friedman-CZMP combination was the best option for developing simplified/unsimplified kinetic models. Determination of reaction mechanism using DAP method by searching for the highest R2 value of regression equation among several candidates was found unreliable. ΔH, ΔG and ΔS values were calculated for 10 °C/min heating rate.

Pyrolysis and combustion kinetics of thermally treated globe artichoke leaves

There are no data in the literature on the energy valorization of globe artichoke (GA) leaves. Thus, an extensive lab-scale experimental torrefaction, carbonization, and coking study was performed. Operative temperatures of 200 °C–1000 °C with 30–120 min residence times were considered. Nonisothermal thermogravimetric analysis was performed at 10, 20, and 40 °C/min heating rates. Pyrolysis and combustion kinetics of raw and thermally treated samples using the Ozawa–Flynn–Wall (OFW) isoconversional method were investigated. All samples exhibited three-stage thermal decomposition behavior: first, moisture and light volatiles evolution common under air and nitrogen; second, carbohydrate fraction decomposition under nitrogen and volatiles combustion; third, lignin decomposition under nitrogen and char combustion. Average activation energy ranges are 54–223 kJ/mol and 223–503 kJ/mol for combustion and pyrolysis, respectively. Some irregular trends appeared when carbonization exceeded 500 °C due to the occurrence of secondary reactions between residual char and evolved gas and the decomposition of some ash components at temperatures reaching 1000 °C. Negative temperature kinetic coefficient appeared at 800–1000 °C as the temperature approached ash softening/fusing temperatures. SEM images indicated amorphous nature and increased porosity from 600 °C, which explains the pyrolysis and oxidation behavior observed in biochar samples produced over this range. Samples pyrolyzed for 30 min showed better elemental and energy results compared to longer times.

The thermal catalytic effects of CoFe-Layered double hydroxide derivative on the molecular perovskite energetic material (DAP-4)

The application of nano-catalytic materials in molecular perovskite energetic materials is of great significance to promote the development of molecular perovskite energetic materials in explosive formulations and propellants. In this paper, the thermal catalytic effects of CoFe-layered double hydroxide derivative on the molecular perovskite energetic material (DAP-4) were studied. In this study, we successfully prepared a new type of CoFe-based photothermal agent (CoFe-500) by heating CoFe layered double hydroxide nanosheets in an Ar atmosphere at 500 °C. And the micromorphology, structure composition, thermal decomposition performances of CoFe-500 and DAP-4/CoFe-500 composite were characterized. The experimental results showed that with the addition of CoFe-500, the initial decomposition temperature and peak exothermic temperature of DAP-4 showed a decreasing trend. With 10 wt% CoFe-500 added, the initial decomposition temperature and peak exothermic temperature of DAP-4 decreased from 305.6 °C to 166.3 °C and 379.0 °C–322.5 °C, respectively (10 °C/min heating rate). The apparent activation energy (Ea) of pure DAP-4 is 172.27 kJ/mol and 175.13 kJ/mol calculated by the Kissinger and Ozawa method, respectively. And with 10 wt% CoFe-500 added, the Ea is reduced to 119.11 kJ/mol and 122.84 kJ/mol, respectively. The possible thermal catalytic decomposition mechanism of DAP-4/CoFe-500 composites was proposed from the thermal analysis and mass spectrometry test results. This work is meaningful to further understand the decomposition performances of DAP-4 in the presence of nano-layered double hydroxide.

Co-pyrolysis of mixed date pits and olive stones: Identification of bio-oil and the production of activated carbon from bio-char

The essential objective of this investigation is to inspect the possibility of exploiting an equivalent blend of locally available bio-wastes, namely date pits (DP) and olive stones (OS), for the production of bio-oil (BO) and bio-char (BC) through thermal pyrolysis route in a semi-batch lab-scale reactor. The pyrolysis products yields from mixed (DP + OS) were optimized by tuning the experimental variables. Co-pyrolysis of mixed (DP + OS) exhibited the maximum output of liquid products (51.11 %, with a BO yield of 37.17 %) at 500 °C using feed particle size of 60 mesh for 80 min at 20 °C/min heating rate. For comparison, the pyrolysis of DP or OS at the previously obtained conditions was also achieved. The liquid products yield from the pyrolysis of DP was (52.30 %, with a BO yield of 31.0 %) compared to (46.0 %, with a BO yield of 24.55 %). FTIR spectroscopy, GC–MS, and elemental analysis were employed to analyze the BO from mixed (DP + OS). The GC–MS outcomes revealed that the produced BO contains phenols, high molecular mass acids, fatty acid esters, aromatics, and alcohols. The BC produced by the pyrolysis of mixed (DP + OS) at the typical pyrolysis conditions mentioned above was exploited to create active carbon (AC) by the optimized ZnCl2 activation method. The AC was identified by BET surface area, FTIR, FESEM, EDX, and XRD. Also, it was exploited to remove dibenzothiophene (DBT) from model gasoline and commercial gasoline. The maximum removal efficiency of DBT reached (90.01 %± 0.50) using 25 mL of 200 mg/L DBT solution employing (0.30 g) of the as-created AC at 50 °C for 80 min. The DBT adsorption results by the AC obeyed the Freundlich isotherm, and best fit the pseudo-first-order kinetic model. For comparison, the BC samples produced through the pyrolysis of DP and OS individually at the typical pyrolysis conditions were also utilized to create AC at the optimal conditions obtained to prepare the best AC sample from mixed (DP + OS) by the ZnCl2 activation method. The so-prepared AC samples were identified for their iodine number and morphology using FESEM technique. The AC samples produced from the BC from DP and OS have also implemented to eliminate DBT from model gasoline using the optimum conditions obtained previously.

Effect of Operating Parameters on Oxidation Characteristics of Soot under the Synergistic Action of Soluble Organic Fractions and Ash.

Diesel particulate filter is used to reduce particulate matter (PM) emission due to the stringent emission standards. The accumulated PM has been oxidized by the periodical regeneration method to avoid pressure buildup. The innovation of this study is to explore the oxidation performance of Printex-U (PU), which is mixed with ash and soluble organic fractions, under different operating conditions. Different aspects of operating parameters, such as the oxygen ratio in an O2/N2 atmosphere, total flow rate, initial PU mass, and heating rate, on PU oxidation properties have been critically discussed using a thermogravimetric analyzer. The oxygen ratio in the O2/N2 atmosphere is positively correlated with the oxidation characteristics of PU. The comprehensive oxidation index (S ) of PU under the 20% O2/80% N2 atmosphere increases by 184% compared with the 10% O2/90% N2 atmosphere. When the initial PU mass is 3 mg, the combustion stability coefficient (Rw) and S reach the best values, which are 55.53 × 105 and 2.03 × 107 %2min–2 ° C–3, respectively. With the increase in the heating rate, the oxidation properties of PU become sensible and deflagration occurs easily, so that 10 °C/min heating rate is the best option. This study provides a theoretical basis for the optimization design of diesel particulates during the regeneration process.

Pyrolysis of Solid Waste for Bio-Oil and Char Production in Refugees’ Camp: A Case Study

The current research focuses on assessing the potential of municipal solid waste (MSW) conversion into biofuel using pyrolysis process. The MSW samples were taken from Zaatari Syrian Refugee Camp. The physical and chemical characteristics of MSW were studied using proximate and elemental analysis. The results showed that moisture content of MSW is 32.3%, volatile matter (VM) is 67.99%, fixed carbon (FC) content is 5.46%, and ash content is 24.33%. The chemical analysis was conducted using CHNS analyzer and found that the percentage of elements contents: 46% Carbon (C) content, 12% Hydrogen (H2), 2% Nitrogen (N2), 44% Oxygen (O2), and higher heat value (HHV) is 26.14 MJ/kg. The MSW pyrolysis was conducted using tubular fluidized bed reactor (FBR) under inert gas (Nitrogen) at 500 °C with 20 °C/min heating rate and using average particles size 5–10 mm. The products of MSW pyrolysis reaction were: pyrolytic liquid, solid char, and gaseous mixture. The pyrolytic oil and residual char were analyzed using Elemental Analyzer and Fourier Transform Infrared Spectroscopy (FTIR). The results of FTIR showed that oil product has considerable amounts of alkenes, alkanes, and carbonyl groups due to high organic compounds contents in MSW. The elemental analysis results showed that oil product content consists of 55% C, 37% O2, and the HHV is 20.8 MJ/kg. The elemental analysis of biochar showed that biochar content consists of 47% C, 49% O2, and HHV is 11.5 MJ/kg. Further research is recommended to study the effects of parameters as reactor types and operating conditions to assess the feasibility of MSW pyrolysis, in addition to the environmental impact study which is necessary to identify and predict the relevant environmental effects of this process.

Development of a P84/ZCC Composite Carbon Membrane for Gas Separation of H2/CO2 and H2/CH4.

Hydrogen (H2) has become one of the promising alternative clean energy resources. Membrane technology is a potential method for hydrogen separation or production. This study aims to develop a new carbon membrane for hydrogen separation or production. Moreover, the permeation behavior of H2, CO2, and CH4 through a hollow fiber composite carbon membrane derived from P84 co-polyimide and with incorporation of zeolite composite carbon (ZCC) was also examined. ZCC was synthesized via the impregnation method of sucrose into zeolite-Y pores, followed by carbonization at 800 °C. Thus, this filler has a high surface area, high microporosity, ordered pore structure, and low hydrophilicity. The presence of zeolites in ZCC is predicted to increase certain gases’ affinity for the membrane. Various heating rates (1–5 °C/min) were applied during pyrolysis to understand the effect of the heating rate on the pore structure and H2/CO2 and H2/CH4 gas separation performance. Moreover, gas permeation was evaluated at various temperatures (298–373 K) to study the thermodynamic aspect of the process. A characteristic graphite peak was detected at 2θ ∼ 44° in all carbon samples. Scanning electron microscopy (SEM) observations revealed the void-free surface and the asymmetric structure of the carbon membranes. During the permeation test, it was found that gas permeation through the membrane was significantly affected by the temperature of the separation process. The highest permeability of H2, CO2, and CH4 was detected on the composite carbon membrane at a 3 °C/min heating rate with a permeation temperature of 373 K. The thermodynamic study shows that CO2 and H2 have lower activation energies compared to CH4. The transport mechanism of the membrane involved adsorption and activated surface diffusion. The permeation temperature has a large impact on the transport of small penetrants in the carbon matrix.

Adsorptive Removal of Cesium Ions Using Prussian Blue Immobilized Coffee Ground Biochar

Objectives: Among various radioactive contaminants, radioactive cesium is one of the most harmful radionuclides that causes human health issues due to its high emission of gamma-ray, high solubility, high mobility, high fission yield, and long half-life. Different kinds of adsorbents have been developed for the removal of cesium from radioactive wastewater. Especially, biochar has attracted great attention as a potential adsorbent in the treatment of pollutants and for water purification. In addition, Prussian blue is a cubic lattice structure that contains a cage size similar to the hydrated cesium ionic radius, indicating it can selectively remove cesium ions. Therefore, the aim of this study is to investigate the cesium adsorption performance of synthesized Prussian blue-immobilized coffee ground biochar (PB-CGBC) under various experimental conditions for cesium removal from radioactive wastewater.Methods: After wasted coffee ground was washed and dried, it was heated at 400℃ with 10℃/min of heating rate and 5 h of retention time in a furnace with little or no available air. The PB-CGBC was synthesized using a facile co-precipitation method. Fourier transform-infrared spectroscopy, X-ray diffractometer, field emission-transmission electron microscope, Brunauer-Emmett-Teller, and zeta potential analyzer were used to analyze physico-chemical characteristics and surface structure of the synthesized adsorbents. The kinetic and equilibrium experiments of cesium adsorption on PB-CGBC were carried out and the effect of pH, temperature, initial cesium concentration, and contact time were also investigated in a batch system.Results and Discussion: The characteristic analysis clearly confirmed the successful synthesis of PB-CGBC, indicating its abundant functional groups and special surface structure. In the batch study, it was found that the cesium adsorption onto the PB-CGBC was exothermic nature. The Elovich kinetic model and Temkin isotherm also provided a good correlation with the cesium adsorption reaction onto the PB-CGBC. The maximum adsorption capacity of PB-CGBC for cesium was 129.57 mg/g at 15℃ and pH 8 at 40 mM of an initial cesium concentration, which was one of the highest values among those of previously reported adsorbents.Conclusions: In this study, the PB-CGBC was synthesized by immobilizing Prussian blue to the surface of coffee ground biochar and successfully applied for the adsorptive removal of cesium ions. Based on the experimental results, the synthesized PB-CGBC can be served as a great adsorbent for treatment of wastewater polluted with radioactive cesium.

Kavun çekirdeği pirolizine ait kinetik parametrelerin ve termodinamik özelliklerin belirlenmesi

The aim of this study is to examine the behaviour of melon seed pyrolysis and to calculate its kinetic parameters along with thermodynamic properties. The thermogravimetric analysis experiments were conducted from ambient temperature to 800°C under nitrogen atmosphere at the heating rates of 5, 10, 20 and 40°C/min. It was determined that the pyrolysis process underwent through four stages where the second and third stages were the active pyrolysis stages. Kinetic calculations were carried out using model-free Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink and model-based Coats-Redfern methods. The apparent activation energy values of the second and third stages were calculated to be in the ranges of 123.9–215.5 and 141.9– 234.2 kJ/mol, respectively. The Coats-Redfern method demonstrated that the second and third stages fit the reaction mechanisms of F1.65 and D5, respectively. Moreover, the enthalpy, entropy and Gibbs energy changes of the active pyrolysis stages performed at 10°C/min heating rate were determined using the results calculated from the model-free kinetic methods. The results obtained in the present study will be useful to provide necessary information needed for the design of melon seed pyrolysis processes.

STUDY TO MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Mg-Zn-Fe-Cu-Co AS HIGH ENTROPY ALLOYS FOR URETERAL IMPLANT APPLICATION

Magnesium and its alloys are promising candidates for degradable materials with good biocompatibility. Alloys based on Mg-Zn-Fe-Cu-Co compositions were designed using the equiatomic method of high entropy alloy. This paper discusses the microstructure and mechanical properties of these new high entropy alloys. Pure Magnesium (60 µm), Zinc (45 µm), Fe (10 µm), Cu (63 µm), and Co (1 µm) powder were mixed and milled using a shaker mill at 700 rpm for the 1800s. The resulting milled powders were compacted and sintered at 300 MPa for 180s and 600 MPa for 120s. Sintering was performed at 700oC for 2 hours in a tube vacuum furnace at a 5 °C/min heating rate under a high purity argon atmosphere. Microstructural analyses and mechanical tests were performed based on the American standard of testing and measurement. The alloys were basically multiphase and crystalline. The 20Mg-20Zn-20Fe-20Cu-20Co alloy consisted of the HCP phase and cubic phase. The physical and mechanical properties of Mg-Zn-Fe-Cu-Co were affected by the magnesium content in the matrix alloys. The presence of pores indicated uncomplete compaction and sintering process. The alloys have a medium hardness of between 286.06 HV - 80.98 HV, while the densities of the alloys were relatively moderate in the range of 3.057 g.cm-3 to 1.71 g.cm-3. Solid solution and intermetallic precipitation strengthening were believed the primary strengthening mechanics of the alloys. It is concluded that high entropy is a promising method for the processing of Mg alloys. Alloy with a chemical composition of 20Mg-20Zn-20Fe-20Cu-20Co had optimal mechanical properties that meet the minimum requirements of high entropy alloys as candidates for ureteral implant applications.

The effects of TiH2 on the thermal decomposition performances of ammonium perchlorate-based molecular perovskite (DAP-4)

ABSTRACT In order to promote the development of molecular perovskite energetic materials, studying thermal decomposition performances of AP-based molecular perovskite energetic materials ((H2dabco)[NH4(ClO4)3], DAP-4) catalyzed by metal hydrogen storage fuel is significant. In this study, the morphology, structure and thermal decomposition characteristics of TiH2, DAP-4 and DAP-4/TiH2 composite materials were characterized and investigated. The experimental results showed that the DAP-4 peak exothermic temperature at different heating rates both showed a decreasing trend with TiH2 content increased. With 20 wt% TiH2 added, the DAP-4 peak exothermic temperature decreased from 394.3 ℃ to 352.8 ℃ (10 ℃/min heating rate), and the apparent activation energy (Ea ) also decreased from 201.5 KJ/mol to 182.3 KJ/mol. A possible catalytic thermal decomposition mechanism of perovskite catalyzed by TiH2 was proposed. This work is helpful to further understand the thermal decomposition characteristics of molecular perovskite energetic materials in the presence of metal hydrides.