Search

Thermal runaway is a frequent source of process safety issues, and the uncontrolled release of chemical energy puts reactors at risk. The design of the exothermic reactor faces challenges due to the selective sensitivity of the product to high temperatures and the need to increase the lifetime of the catalyst, optimize the product distribution, and improve the thermodynamic properties. Phase change material (PCM) encapsulation is recommended to reduce leakage, phase separation, and volume change problems. This work introduces encapsulated PCMs to improve reactor temperature control and minimize thermal runaway in exothermic processes. The warning temperature value setting effectively inhibits fugitive exothermic reactions and enhances heat transfer. When a sufficient quantity of encapsulated PCMs is input, the response speed will automatically accelerate. Spontaneous acceleration of the reaction rate due to thermal runaway of the reaction may be completely avoided by adding a sufficient amount of encapsulated PCM. Microencapsulation is used to control volume changes and inhibit thermal reactions. Preventive strategies include cooling, depressurization, safety release, emergency resources, and reaction containment. Encapsulated PCMs improve mechanical and thermal properties, surface-to-volume ratio, heat transfer surface, thermal capacity, and efficiency. [ABSTRACT FROM AUTHOR]

The heat and mass concept is analyzed through the properties of the Dufour number, chemical reactions, and the heat generation parameters on MHD incompressible nanofluids flow. The MATLAB software with the finite difference method (FDM) was employed to find and graphically present the system’s numerical solutions. This study finds an increased Dufour number enhancing the flow speed and hotness of the nanofluid. The chemical reactions released heat energy to the surrounding environment, escalating the nanofluid’s temperature and decreasing the concentration of the nanoparticles. The rate of permeability strengthens the flow velocity by improving the flow network. The increased heat generation parameter influenced the increase in nanofluids’ velocity and temperature. This study can be considered in some applications, such as designing heat exchangers, solar cells, climate changes, and separation process industries.

The crucial function of bioactive ligands in the interaction with diverse proteins has garnered significant attention in the fields of pharmacokinetics and pharmacodynamics, hence generating considerable interest in the discipline of medicinal chemistry. To better comprehend its molecular mechanism, we implored a detailed biophysical analyses (using multi-spectroscopic, calorimetric, and computational tools) of the carrier protein Lysozyme, Lyz (also known as "Muramidase") with Yohimbine (Yoh). The binding constant (K) of the Lyz-Yoh complex was estimated to be 105 M−1, exhibiting a progressive decline as temperature increased. The thermodynamic-profiling indicated the binding to be associated with an exothermic interaction driven by entropy. The confirmation of spontaneous binding is evidenced by the observed decrease in free energy. The variation in ionic strength indicated that non-polyelectrolytic forces were involved in the association. In addition, it was investigated how different metal ions affected the Lyz-Yoh binding. Calorimetric studies revealed the binding to be exothermic in nature, which also aligns with spectroscopic data. Results from circular dichroism (CD) experiments, demonstrated the structural alterations brought about in Lyz by Yoh. The likely binding sites and protein residuals to the ligand (Yoh) were illustrated using theoretical techniques, viz., molecular docking and molecular dynamic (MD) simulation. In clinical and pharmaceutical assessments, these metrics are especially relevant for rational drug development. [Display omitted] • Spontaneous and thermodynamically favorable association. • Competition between the metal ions and Yoh binding to Lyz at the same binding site. • A crucial role was played by the hydrophobic forces and hydrogen bonding. • Lyz microenvironmental changes after ligation with Yoh. [ABSTRACT FROM AUTHOR]

The increasing presence of chloramphenicol (CAP) in aquatic environments each year has led to serious concerns regarding potential adverse effects on human health, the environment, and aquatic organisms. If CAP residues are not sufficiently removed during wastewater treatment, they can migrate into the aquatic environment and eventually end up in the food chain. Therefore, the removal of CAP from river bodies is of great importance. In this research study, a novel sodium bicarbonate (NaHCO3)-impregnated coconut husk-activated carbon (CHAC) was developed through an impregnation method for CAP removal. The introduction of NaHCO3 on the CHAC surfaces results in the formation of OH– and H2O functional groups. The presence of a hydroxyl group appears mainly due to the water molecules found in the middle layer of the adsorbent and might be due to the water molecules that are physically adsorbed. This suggests that OH– groups found on the outer layer of the NaHCO3-impregnated CHAC are the main contributors to the removal of CAP through chemical interaction and electrostatic attraction. Based on the response surface methodology approach, the best preparation conditions for activation temperature, activation time, and IR were identified to be 500 ℃, 1 h, and 0.5, respectively. The optimized CHAC was found to be homogeneous and had a mesoporous type of pores with a BET surface area of 438.2 m2/g. In the batch adsorption study, the uptake of CAP onto CHAC increased as both the initial concentration of CAP and contact time increased. In terms of the effect of solution pH, CAP removal was highest at pH 2 and lowest at pH 13. The Langmuir isotherm and pseudo-first-order (PFO) kinetic were the best-fitted models for CAP adsorption. Besides, the adsorption process was mainly governed by the film diffusion mechanism. Based on the thermodynamic study, CAP adsorption onto CHAC was found to be exothermic in nature and spontaneous. [ABSTRACT FROM AUTHOR]

Due to inappropriate energy consumption and subpar waste management, the growing population leads to an increase in energy demand and environmental damage. The creation of biogas enhances the management of organic waste and provides renewable energy. The production of biogas, which is a mixture of several gases, primarily methane and carbon dioxide, occurs during the four phases of aerobic digestion (AD). The four stages are hydrolysis, acidogenesis, acetogenesis, and methanogensis. Biogas comprises 50–70% Methane, 25–40% carbon dioxide and remaining traces of gases. In this paper, these biogas production processes are not thoroughly studied utilizing thermodynamic principles. Using thermodynamic criteria, this article analyses and assesses why the aerobic digesting process is spontaneous. Entropy, enthalpy, and Gibbs free energy of reactions during the various stages of the formation of biogas are examined. At Standard Temperature and Pressure Conditions (STP), the combined four phases of biogas formation are exothermic and spontaneous based on the analysis of Entropy, enthalpy, and Gibbs free energy of reactions from balanced equations at standard conditions of temperature and pressure. A unit mole of glucose is used to compare the energy released during photosynthesis with the energy released during biogas burning. Three moles of methane can be produced from decomposition of glucose. The combustion of three moles of methane yields 2406.876 kJ energy and if the same amount of moles of biogas (60% methane and 40% carbon dioxide) burns the energy yield is reduced to 1604.584 kJ. From the energy captured by photosynthesis i.e., 2808.1 kJ/mol 57.141% of the energy is recovered in the biogas combustion process. This efficiency reaches to 85.711% if pure methane is burned. As the separation of methane from biogas, mixture in actual plants is not economically feasible the combustion of methane gas the ideal limit of the efficiency.

α-Fe2O3 coated hydroxy magnesium silicate (HMS) was prepared by the coprecipitation method and was used for the sorption of Cr(VI) from the aquatic environment. FT-IR, XRD, and SEM characterised the investigated composite. The influence of pH, shaking time, Cr(VI) concentration,and the temperature was investigated. The results obtained are fitted well with the pseudo-second-order kinetic model. Besides, Freundlich isotherm is adequate than the Langmuir isotherm. The adsorption was observed to be exothermic, spontaneous, and accompanied by increasing the system's randomness. The adsorption of chromium attained equilibrium after 60.0 min. The maximum adsorption capacities of α-Fe2O3/HMS composite for Cr(VI) were 10.75 mg/g obtained at a pH of 2. [ABSTRACT FROM AUTHOR]

In this paper, a new thermal energy storage (TES) scheme of basalt fiber bundles is proposed. This basalt fiber bundle TES tank adopts two-stage runner arrangement to increase the specific surface area and improve the heat exchange effect. Based on this, a variable flow rate and preheating control scheme is proposed to enhance the discharging stability. The results when the air initial flow rate is 1m/sshow that the two methods of automatically controlling the flow rate change and using two tanks in series to make full use of the waste heat can significantly increase the stable discharging time of the TES tank. The increase in the stable discharging time reached 115% with variable flow rate scheme. And the simultaneous use of variable flow and preheating control schemes can extend the stable discharging time to 166% of the constant flow scheme. This TES tank can provide a wide heating power range and the maximum discharging power per unit area reaches 1.005MW±1% when the initial flow rate is 1m/s. However, it is difficult for honeycomb and packed bed to achieve such output under the same flow rate. In short, this new scheme can realize the coexistence of high thermal energy storage density, strong stable discharging, small volume and high discharging power, and can be used in mobile thermal energy storage system to meet user groups with significant differences in heating demand.

Calcium Hardness (Ca. H) and total Hardness ions in drinkable groundwater cause great problems for the entire world especially, the population communities which are located far from surface water sources. The present study investigates the use of Sodalite Bearing Modified Illite (SBMI) as a sustainable and new technique to eliminate these ions from drinkable groundwater to compatible with the instruction of the World Health Organization. The methodology was achieved by using a new method to remove these ions' excess calcium Hardness and total Hardness depending on two main processes; the adsorption as a first step and the coagulation-flocculation-sedimentation process as a second step. The results of this study were achieved through conducting three tasks; (1) Chemical analysis surveys for all the groundwater wells, to determine the areas which are more affected by these salts, and plot them on the location maps. (2) Conducting the alkaline modification of the Illite ore to obtain the (SBMI) which has a high surface area and high adsorption ability, and it had been characterized by using XRD, XRF, SEM, and FTIR techniques. (3) The experimental studies were conducted to evaluate the effect of the modified Illite on raw groundwater containing a high concentration of hardness ions, through the batch studies to determine the factors which affected its ability for removing these ions from groundwater. The present study illustrated that the removing efficiency for both total hardness (Ca. H + Mg. H) and calcium hardness (Ca. H) reached about 98%. Finally, the present study recommended using this technique, when there is a requirement for large quantities of treated water at a low cost. [ABSTRACT FROM AUTHOR]

Utilization of synthetic dyes in different sectors has been identified as one of the major sources of environmental degradation; as a result, removal of their remnants from the industrial effluent is highly encouraged for conserving our environment. In this study, the synthesized plantain leaf biochar (PLB) was used for adsorbing synthetic malachite green (MG). The synthesized PLB was characterized through pHpzc, BET, XRD, SEM and FTIR spectrometry. The sequestration of MG onto PLB confirmed by FTIR and SEM was optimized by varying the adsorption parameters. The BET surface area (986.35 m2/g) and average pore diameter (44.13 Å) showcased PLB as an efficient mesoporous biochar capable of adsorbing MG (>99%) at optimum conditions of pH (8.0), initial MG concentration (50 mg/L), adsorbent dosage (0.2 g/L), contact time (80 min) and temperature of 301 K. Redlich-Peterson and Avrami fractional model best fitted the adsorption isotherm and kinetic model, respectively. ΔGo and ΔHo being negative confirmed the feasibility and exothermic nature of the adsorption process. The outstanding regeneration (>97%) of PLB after the fifth regeneration cycle established PLB as a potential sustainable green adsorbent for future industrial wastewater treatment.

Agricultural waste materials from common bean (Phaseolus vulgaris L.) and cowpea (Vigna unguiculata subsp. unguiculata) vines were investigated as adsorbents to remove methylene blue (MB) from aqueous solution. Both vines exhibited efficient adsorption of MB. Characterization of the adsorbents was performed by infrared spectroscopy, scanning electron microscopy and N2 adsorption at 77 K. Composition was determined by the van Soest method. The adsorption isotherms of the vine adsorbents for MB fitted a Langmuir model well and the kinetics followed a pseudo-second-order model. The adsorption capacities of common bean and cowpea vines for MB were 181.82 and 144.93 mg/g, respectively, and the adsorption was a spontaneous and exothermic process. The high adsorption performance was mainly due to the hierarchical pore structure and abundant surface functional groups of the vine materials. The adsorption mechanism involved pore filling, electrostatic attraction, hydrogen bonding, π–π interactions, ion-exchange and n–π interactions. The results revealed that common bean and cowpea vines can be used as effective low-cost adsorbents in the treatment of contaminated wastewater. [ABSTRACT FROM AUTHOR]

Transition metal complexes of synthesized organic ligands incorporating INH were successfully investigated by potentiometrically. The stability constants of these binary complexes were evaluated and order of stability constant found as above Zn(II) > Co(II) > Ni(II) > Mn(II) > Cu(II). Magnetic moment value clearly indicates that newly prepared transition metal complexes of N-[(E)-(2-Hydroxyphenyl)methylen]isonicotinohydrazid are paramagnetic in nature. The stability constants for complexes decrease with an increasing temperature, indicating that the composition equilibrium is exothermic in nature. Also the change in enthalpy (ΔH) and change in Gibb's free energy (ΔG) were negative for all of the systems which suggested that all of the reactions were exothermic. The change in entropy (ΔS) found positive for most of the complexes which indicate in metal–ligand binding process is entropy favourable. Metal complexes of organic ligand shows moderate antibacterial activity against gram positive and gram negative bacteria. It also possesses prominent antifungal activity for Nickel (II) complex. Biological evaluation results of transition metal complexes show superior pharmacological applications as compared to organic ligand. [ABSTRACT FROM AUTHOR]

Accelerating Rate Calorimetry (ARC) is a widely used adiabatic calorimetry technique to evaluate thermo-kinetics of hazardous chemical reactions. Most ARCs rely on measurement of temperature at the external wall of the ARC sphere to evaluate the temperature rise rate, and therefore exothermic reaction rate. We report large temperature gradients between the center and wall for a granulated solid sample tested using an un-stirred ARC that leads to varying spatiotemporal temperature profiles. Such gradients were found to be significantly lowered in organic liquid samples, enabling classifying some granulated solid samples as heat transfer-limited systems. This study reveals that such temperature gradients obviate estimation of representative exothermic reaction rate, manifesting in hazard underestimation through erroneous pressure and apparent conversion profiles. Next, the addition of an inert was demonstrated to reduce the magnitude of such gradients, thereby enabling relatively accurate hazard assessment and offering a potential solution. Lastly, several strategies are outlined to allow researchers to identify and mitigate the influence of gradients during hazard assessment. Researchers must be cognizant of the potential for gradients when analyzing and interpreting ARC data for thermo-kinetic modeling and hazard evaluation. During hazard evaluation, researchers should confirm that no significant gradients exist or find ways to de-sensitize their hazard assessment parameters if gradients exist and cannot be minimized. [ABSTRACT FROM AUTHOR]

A simple low cost demonstration for the school and undergraduate students to explain the thermodynamics of condensation and evaporation process. [ABSTRACT FROM AUTHOR]

• Oxidative exothermic of coal were accurately measured by C80 microcalorimeter. • Oxidative exothermic of coal were investigated at various oxygen and particle levels. • Limiting parameters of CSC at various O 2 and particle levels were examination. Oxygen concentration and particle size play critical roles in the combustion of coal. Notably, the low temperature oxidation stage is considered pivotal for coal spontaneous combustion (CSC). In this study, we examined the exothermic oxidation of low-temperature weakly caking coal. We used a C80 microcalorimeter to assess the impact of different oxygen concentrations and particle sizes. For weakly caking coal during low-temperature oxidation, the heat flow (HF) curve decreases as oxygen concentration drops. The characteristic temperature increases, and the HF curve shows a noticeable lag. Under identical external conditions, decreasing the particle size of coal results in a reduced minimum floating coal thickness, lowers the oxygen concentration needed for CSC, increases the upper-limit of air leakage intensity, and makes the coal more susceptible to CSC. Reducing the particle size significantly increases the exothermic heat release during low-temperature oxidation, leading to a higher risk of CSC. These research results not only deepen the understanding of the law of coal spontaneous combustion, but also provide a scientific basis for improving the technical level of coal spontaneous combustion fire prevention and control. [ABSTRACT FROM AUTHOR]

This study reported the accumulation of Methylene Blue (MB) by sulphonated Solanum virginianum carbon (SSVC) using batch technique. Adsorption studies are conducted in altered initial dye concentrations, adsorbent doses, pH, contact time and temperature. The removal of MB increases with decrease in concentration of dye. The experimental data was analysed by Langmuir, Freundlich and Temkin models. The adsorption capacity (Qo) of SSVC was found to be 24.12 mg/g. The process of dye accumulation follows second order kinetics. From the effect of temperature, thermodynamic parameters such as the free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined. [ABSTRACT FROM AUTHOR]

Scientific-based assessment and management of the state of stored grain based on reliable information provides a reliable forecast of the direction of interrelated physical, chemical and biochemical processes in order to take timely measures to prevent quantitative and qualitative losses and food safety of grain. Based on the stationary nature of the grain storage process, it is proposed to use a system of differential equations describing the conditions of heat transfer by convective transfer, thermal conductivity, and oxygen diffusion through a layer of anisotropic, porous material to prevent self-heating of the grain. The level of the activation barrier Eа=123 kJ/mol of the grain mass is established as a thermodynamic system, when it reaches a stable internal heat source. To take into account the main factors and forecast possible exothermic processes in the grain mass (on currents, in elevators, during transportation, storage, etc.), it is proposed.

In this work, NaOH-activated Aerva javanica leaf (NAJL) powder was successfully developed as a cost-effective adsorbent for removal of crystal violet (CV) from an aqueous environment. The prepared adsorbent was characterized using FTIR, SEM, and their surface area was determined by BET technique. Different parameters affecting the adsorption of CV dye such as pH solution, adsorbent dose, equilibrium time, initial CV concentration, and temperature were investigated. The results revealed that the best-optimized values were found as pH–9, dose–20 mg, time–30 min, temperature– 25 °C. The adsorption experimental data exhibited excellently fitted well to the nonlinear Langmuir isotherm and Pseudo-first-order kinetic models. The maximum monolayer adsorption capacity of CV dye was 315.2 mg/g. The experimental parameters of thermodynamic analysis exhibited that the CV dye adsorption onto NAJL powder was exothermic and spontaneous. Electrostatic attraction, π-π interactions, and Hydrogen bonding were the mechanism behind the adsorption of CV dye.

Burgeoning pesticide usage in agriculture sector required to be evaluated by assessing the adsorption rate in soils. The herbicide triasulfuron was used in this research to analyze its sorption behavior in seven distinct soils using batch equilibrium methodology. The adsorption coefficient (Kd) values ranged from the 3.32 to 29.7 µg/mL. Peshawar soil displayed the highest Kd value because of the distinct physiochemical properties when compared with the other six samples. Gibbs free energy exhibited negative values displaying less contact between soil particles and pesticides, showing the exothermic nature of the phenomena. A negative association was observed between the pH of the soil samples and Kd (R2 = −0.71) but a direct relation with the organic content (R2 = 0.74). Triasulfuron mitigation was performed by the economical remediation of soils using acid-activated charcoal prepped from Saccharum officinarum husk. Activated carbon derived from biomass displayed the great potential for triasulfuron removal from soils.

In this work, NaOH-activated Aerva javanica leaf (NAJL) powder was successfully developed as a cost-effective adsorbent for removal of crystal violet (CV) from an aqueous environment. The prepared adsorbent was characterized using FTIR, SEM, and their surface area was determined by BET technique. Different parameters affecting the adsorption of CV dye such as pH solution, adsorbent dose, equilibrium time, initial CV concentration, and temperature were investigated. The results revealed that the best-optimized values were found as pH–9, dose–20 mg, time–30 min, temperature– 25 °C. The adsorption experimental data exhibited excellently fitted well to the nonlinear Langmuir isotherm and Pseudo-first-order kinetic models. The maximum monolayer adsorption capacity of CV dye was 315.2 mg/g. The experimental parameters of thermodynamic analysis exhibited that the CV dye adsorption onto NAJL powder was exothermic and spontaneous. Electrostatic attraction, π-π interactions, and Hydrogen bonding were the mechanism behind the adsorption of CV dye. [ABSTRACT FROM AUTHOR]

The foreseeable global cobalt (Co) crisis has driven the demand for cathode materials with less Co dependence, where high-nickel layered oxides are a promising solution due to their high energy density and low cost. However, these materials suffer from poor cycling stability and rapid voltage decay due to lattice displacement and nanostrain accumulation. Here, we introduced an exothermic TiN dopant via a scalable coating method to stabilize LiNi 0.917 Co 0.056 Mn 0.026 O 2 (NCM92) materials. The exothermic reaction of TiN conversion generates extra heat during the calcination process on the cathode surface, promotes the lithiation process, and tunes the morphology of the cathode material, resulting in compact and conformal smaller particle sizes to provide better particle integration and lithium diffusion coefficient. Moreover, the Ti dopant substitutes the Ni 3+ site to generate stronger Ti-O bonding, leading to higher structural stability and extended cycle life. The Ti-doped NCM (NCM92_TiN) shows a remarkable cycling stability of maintaining 80% capacity retention for 400 cycles, while bare NCM92 can only reach 88 cycles. Furthermore, the NCM92_TiN cathodes demonstrate an enhanced rate capability and achieve a discharge capacity of over 168 mAh g -1 at 5C.

In this work, carbon nanotubes (MWCNTs) were utilized as efficient adsorbents for pantoprazole (PP) removal. We used MWCNTs that were synthesized using the chemical vapor deposition process. The physical characteristics of MWCNTs were described by Brunauer-Emmett-Teller (BET) contact area, surface functional group analysis by the point of zero charge (pHPZC), Fourier transform infrared (FTIR) analysis, Scanning electron microscope (SEM), X-ray diffraction (XRD), and Transmission electron microscopy (TEM). The single-point BET surface area of the MWCNTs was found to be 98.7 m2 g-1, with the median pores' diameter of 30.9 nm and an average pore(s) volume of 0.764 cm3 g-1. Effective parameters on the PP removal including, pH, contact time and initial amount of adsorbents were optimized, revealing maximum PP removal at pH=6.0 after 25.0 min when 0.026 g MWCNTs. The pseudo second-order kinetic model for adsorption of PP on the surface of both adsorbents revealed the high value of correlation coefficient, indicating the high ability of the pseudo second-order model for representation of experimental results. Adsorption equilibrium studies indicated that the Freundlich isotherm efficiently represented MWCNTs adsorption data. The thermodynamic parameters (Gebbs free energy, enthalpy, and entropy) of adsorption process were calculated. Results had shown that adsorption of PP on the MWCNTs is feasible, spontaneous, and exothermic process in the temperature range of 25-76 °C. [ABSTRACT FROM AUTHOR]

Graphene synthesis has been carried out electrochemically with the source being graphite rods mechanically separated from waste model batteries. TEM, Raman spectroscopic analysis has been used to characterize the exfoliated graphene. Mesoporous graphene nanoparticle has been confirmed through BET analysis wherein the surface area and the pore diameter has been reported as 710.4 m2/g and 29.6 Å respectively. The synthesized graphene nanoparticle is used to adsorb Methylene blue (MB) dye which is toxic by nature and the parameters studied are the dosage of adsorbent graphene, MB concentration, temperature and contact time. From UV, XRD, and FTIR the adsorption of MB on graphene has been confirmed. The graphene's adsorption capacity at 300C was 272 mg/g. The adsorption followed fitted Temkin isotherm whereas the mechanism was pseudo-second-order. Physisorption and spontaneous adsorption process was reported by the thermodynamic study of the adsorption process. [ABSTRACT FROM AUTHOR]

The afterburning effect of aluminized explosives makes them have strong damage ability to soft targets, but the aluminum particles in the composition often cannot achieve proper combustion. The high ignition temperature of micron aluminum powder is one of the main reasons. In this work, we introduce nanothermite reaction with low onset temperature (<660 °C) into aluminized explosives by replacing the base explosives with energetic coordination polymers (ECPs). The decomposition products of many ECPs contain corresponding metal oxides that will react with aluminum via thermite reaction. Three kinds of ECPs ([CoC2H4N8O4]n, [NiC2H4N8O4]n and [CuC2H4N8O4]n) are constructed and compounded with nano‐aluminum (nano‐Al) particles to form aluminized ECPs. The influence of metal ion species and Al/Metal (Al/Me) molar ratio on their energetic properties are systematically studied. The results show that the exothermic thermite reaction with low onset temperature plays an important role in the combustion propagation of aluminized ECPs, and the possible mechanism is proposed. When the Al/Me molar ratio is 3–4, the aluminized ECPs have the best peak pressure and pressurization rate. At the optimum molar ratio, the pressure and pressurization rate of aluminized ECP(Co) are much higher than those of aluminized ECP(Ni) and ECP(Cu). Among the three kinds of aluminized ECPs, the aluminized ECP(Co) has the best energetic characteristics and can be used as a preferred choice. However, for the applications that require a long‐time heat supply, aluminized ECP(Cu) will be suitable. [ABSTRACT FROM AUTHOR]

Hydrocarbon reforming route has gained immense attention for producing energy‐effective renewable fuels and/or chemicals in the recent era. In this simulation study, O2 addition and CH4 recycling's effect on the dry oxidative reforming reactor's performance was investigated. Aspen HYSYS simulation software was used to assess a biogas‐to‐syngas conversion process's feasibility by integrating with the CH4 recycling loop and CO2 sequestration in a dry oxidative reforming process. Simulation runs were performed by varying the O2/CH4 ratio content from 0 to 0.20 and temperature (450 to 700°C). Results illustrated that CH4 conversion improved by re‐injecting of unreacted CH4, followed by CO2 sequestration to a great extent. In dry oxidative reforming, at stoichiometry O2/CH4 ratio of 0.17, CH4 conversion (21.7%), and CO2 conversion (3.3%) were obtained at 500°C, with 1.2 H2/CO ratio. Further, 0.308 kg mole/h of H2 could be produced with biogas (1.0 kg mole/h) at optimal parameters 500°C (temperature) and 0.17 (O2/CH4 ratio) by using recycling loop in one cycle. Thus, dry oxidative reforming coupled with the CH4 recycling unit provides a better option for syngas/H2 production and remarkably addresses high energy demand in the dry reforming process. [ABSTRACT FROM AUTHOR]

Introduction. The paper discusses the use of different methods of the hardening concrete’s temperature regime, depending on the boundary conditions specified in the design and construction of the object. Such conditions include the temperature regime of concrete holding, the turnover rate of the formwork and the construction time of the facility, as well as other factors. The aim of the research is a compilation of the various methods of investigation of the temperature regime of hardening concrete, aimed at providing the required timing of the formwork and technological equipment turnover to ensuring the consumer properties of the structures. The scientific novelty of the research lies in the updating and testing of methods for regulating the hardening concrete’s heating, ensuring the formation of the required consumer structures’ properties not previously used in transport and civil construction and based on preliminary modeling of thermal processes occurring in the hardening concrete through the calculation software. The authors on the example of several large objects’ construction consider the most common situations associated with the selection of construction technology in difficult natural conditions by taking into account the required consumer properties: concreting of large-mass structures in a limited time in the warm season and low-mass structures in winter concreting. The research is relevant in view of the large-scale construction in our country as well as of the facilities’ reconstruction.Materials and methods. The authors carried out the research with the use of modern settlementmeasuring and analytical systems taking into account the change in the thermal stress state of hardening concrete as a function of the temperature change of the concrete mix over time. The use of the modern computational and analytical complex in the physical modeling of the thermo physical processes of hardening concrete made it possible to obtain results as accurately as possible and comparable with observational data obtained during the construction process.Results. The results allowed authors to project the objects’ concreting of erected in various predetermined conditions while observing the required terms of formwork turnover and ensuring the necessary consumer properties.Discussion and conclusions. The authors propose measures, the implementation of which makes it possible to build complex construction projects in a short time in special climatic conditions. The paper is useful for engineering and technical personnel and for professionals involved in the study of thermal processes of hardening concrete.

The need to explore an environmentally friendly and cheaper adsorbent for removal of dye from polluted water has imposed a requirement for thorough thermodynamic studies of dye removal from synthetically polluted water. The sorption capacities of untreated corncob charcoal (UCC), treated corncob charcoal (TCC) and commercially available activated carbon (ACC) for malachite green (MG) were determined at pH 3.10 and 5.10, in the temperature range 5–30°C using the batch adsorption method. The adsorption capacity of each adsorbent for MG decreased with the increasing temperature in a manner suggestive of exothermic process. The equilibrium adsorption data were well fitted with Freundlich isotherm. The enthalpy of adsorption is higher at pH 5.10 for any particular adsorbent type compared to data collected at pH 3.10. The adsorption of MG is greatest in activated charcoal at pH 5.10. At pH 3.10 the adsorption process results in reduction in entropy changes in each adsorbent such that ΔSo TCC > ΔSo UCC > ΔSo ACC following the same trend as the change in enthalpy. At pH 5.10, however, ΔSo TCC > ΔSo ACC > ΔSo UCC and the change of enthalpy of adsorption of MG to the adsorbent follows the same order, ΔHo TCC > ΔHo ACC > ΔHo UCC. The values of the enthalpy changes suggest essentially physisorption in all cases.

In this paper, a variable-volume Continuously Stirred Tank Reactor (CSTR) deterministic exothermic model has been formulated based on the Reynold Transport Theorem. The numerical analysis of the formulated model and the identifiability of its physical parameters are done by using the least squares and the Delayed-Rejection Adaptive Metropolis (DRAM) method. The least square estimates provide the prior information for the DRAM method. The overall numerical results show that the model gives an insight in describing the dynamics of CSTR processes, and 14 parameters of the CSTR are well identified through DRAM convergence diagnostic tests, such as trace, scatter, autocorrelation, histograms, and marginal density plots. Global sensitivity analysis was further performed, by using the partial rank correlation coefficients obtained from the Latin hypercube sampling method, in order to study and quantify the impact of estimated parameters, uncertainties on the model outputs. The results showed that 7 among the 14 estimated model parameters are very sensitive to the model outcomes and so those parameters need to be handled and treated carefully. [ABSTRACT FROM AUTHOR]

Introduction. The paper deals with the issues related to the determination and registration of the own thermo-stressed state formed in concrete while hardening and used to provide the required consumer properties in the Crimean bridge construction. Therefore, the problem is relevant because of the deadlines for the construction of such facility in the conditions of rough terrain and dry hot climate, and also taking into account the development of the unique non-class facilities in Russia.Materials and methods. The research is carried out in real-time conditions with the usage of modern measuring systems in practice, allowing to control the process of temperature and strength of hardening concrete in time. The modern computational and analytical complex, which is repeatedly tested under real conditions and by thermophysical calculations of hardening concrete of various class objects and massiveness, is used.Results. The results of the intrinsic thermo-stressed state of hardening concrete are presented in determining the permissible temperature gradient, which make it possible to accelerate the process of erecting the object with observance of the necessary consumer properties.Discussion and conclusion. The main conclusions and suggestions are made taking into account the intrinsic thermally stressed state of the concrete when it was hardened during the construction of the Crimean bridge. The paper would be interesting and useful for engineers and technical workers engaged in real production conditions, and for specialists dealing with the issues of the thermophysical processes occurring in concrete hardening and with the problems of ensuring the high consumer concrete properties in structures.

Introduction. The article discusses the cements’ heat generation issues used in the construction of the bridge across the Kerch Strait. This question is important because of the construction in dry hot climate’s conditions.Materials and methods. The research is conducted with the use of modern information and analytical systems, which allow to obtain the results closing to real conditions. Therefore, the research results of the cement type influence on the dissipation rate and the nature changes of its integral isothermal heat dissipation are shown in the article. The modern design complex repeatedly tested in practice while carrying out thermal calculations of concrete hardening on different massive objects is applied for the research.Results. As a result, the recommendations by the cements of various types’ usage in construction of the Kerch bridge and other similar extra-curricular facilities, which are included in the basis of the developed technological regulations for the production of preparatory, reinforcement, formwork and concrete year-round construction, are presented. The article would be interesting and useful for engineering specialists, who work in real construction conditions, and for experts, who deal with the problem of high consumer concrete properties’ ensuring.

The current investigation has attempted to investigate the adsorption pattern of a persistent organochlorine insecticide, Endosulfan via the standard batch equilibrium method. Results for the model application are expressed adsorption co-efficient Kd ranging from 0.7 to 10 µg/mL. Existence of physisorption was confirmed through an exothermic and low interaction between Endosulfan and soil samples are shown via Gibbs free energy (ΔG) with negative values. Statistical significance of the results was shown by negative association between soil pH and Kd (R2 = −0.74 and p = 0.01), while organic matter and adsorption were related to one another in a positive manner (R2 = 0.92). Additionally, statistical significance of the results was also expressed by ANOVA analysis results, indicating a p value of <0.05. In the sub-sequential manner, activated peanut shells powder, as a green adsorbent, has been used for Endosulfan pesticide removal from the selected soil samples. Activated peanut shells powder was exposed to the FT-IR analysis showing presence and augmentation of different groups. Endosulfan maximum removal was observed in 5 ppm concentration to be 78%, while in 7.5 ppm, it was 70%. Currently devised method can be efficiently used in a cost-effective manner for the removal of obnoxious pesticides from environmental compartments. [ABSTRACT FROM AUTHOR]

The usage of ultrasonic-assisted Spirulina platensis (UASP) algal powder for the adsorption of Naphthol green-B (NGB) dye was analyzed within environmental conditions. The batch removal investigations were done with various operational conditions including UASP dose, contact time, initial NGB dye concentration and the NGB solution pH to eliminate NGB dye molecules in the aqueous solution. The optimal working conditions for the removal of NGB dye by UASP was showed that contact time (60 min), dose (3 g/L), initial NGB dye concentration (100 mg/L), pH (3), and temperature (30°C). The dye removal data were inspected by utilizing four adsorption isotherm models like Langmuir, Freundlich, Toth, and Hill isotherm models. The experimental data gener-ated best fits within the following isotherm order: Freundlich > Hill > Toth > Langmuir isotherm model. The maximum monolayer adsorption capacity was 137.9 mg/g. The pseudo-first-order, second- order kinetic, and intraparticle diffusion models were probed and the outcomes show that the pseudo-first-order fitted with the adsorption of NGB dye molecules by UASP. Thermodynamic parameters like ΔG°, ΔH°, and ΔS° were determined and the results prove that the NGB adsorption was exothermic, spontaneous, and feasible. The results specify that the UASP has actually been utilized as an inexpensive biosorbent for the removal of NBG dye from aqueous solution. [ABSTRACT FROM AUTHOR]

Goethite, a common Fe(III) oxyhydroxide found in soils and aquifers, is employed in water purification technology due to its high oxo-anion adsorption capacity. In a series of batch equilibrium experiments, goethite suspensions were subjected to varying ionic strengths, concentrations of vanadate and molybdate, and pH values ranging from 3 to 10. These experiments were also carried out at four distinct temperatures, ranging from 10 to 75 °C. The results from over 1400 individual batch equilibrium experiments revealed that the adsorption of vanadate and molybdate generally decreases as the pH increases, as is typically observed for anion adsorption envelopes. However, this decrease was found to be less pronounced for vanadate compared to molybdate, with only the latter showing a sharp adsorption envelope decline at circumneutral pH values near the point of zero charge of the goethite surface. To interpret these findings, the Charge Distribution Multisite Surface Complexation (CD-MUSIC) model framework was employed. According to the model fit, the adsorption of molybdate is primarily governed by an outer-sphere surface complex at circumneutral pH conditions, which remains relatively unaffected by temperature variations, indicating a nearly zero enthalpy of reaction. Similarly, for vanadate, there was also no significant temperature effect, but the reasons differed. For the two inner-sphere vanadate surface complexes, a linear decrease in log K values with temperature was observed, suggesting an exothermic adsorption reaction with negative enthalpy as typical for inner-sphere binding of oxyanions. This was counterbalanced by an increase in log K with temperature for the strong dioxovanadium(V) cation surface complex, which exhibited a positive enthalpy and thus an endothermic reaction typical for cations. As a result, the overall uptake of vanadate by goethite was found to be almost temperature independent as well. [Display omitted] • Over 1400 individual batch equilibrium adsorption experiments were performed. • The experiments were performed at different concentrations, pH, and temperatures. • A CD-MUSIC surface complexation model was found to fit the Mo(VI) and V(V) data. • Inner-sphere Mo complexation is exothermic but not the outer-sphere dominant at circumneutral pH conditions. • Exothermic vanadate adsorption was out-compensated by endothermic vanadyl surface complexation. [ABSTRACT FROM AUTHOR]

Highlights • Cement paste is recommended as a good alternative surface coating material of LWA-PCM for a better compatibility. • Exothermic/endothermic events validate that PCM can delay or prevent ice formation. • When the replacement of LWA is up to 50% vol., the heat released by PCM is sufficiently high to inhibit ice formation. • Time offset between solidification of PCM and pore solution is relevant to effective utilization of PCM in improving freeze-thaw resistance of concrete. Abstract This paper investigates the preparation and assessment of mortar-phase change materials (PCM) systems to gain a full understanding of using the heat stored in PCMs to delay or prevent ice formation in concrete. Desirable PCMs and light weight aggregates (LWA), which act as carriers of the PCMs, were first selected based on their thermal and physical properties. LWAs containing PCMs were prepared and assessed for different combinations of materials. Cyclic freeze-thaw mass loss, latent heat attenuation, and FTIR tests were conducted to characterize the stabilities of the LWA-PCMs. The thermal performances of the mortars containing LWA-PCMs were investigated using a longitudinal guarded comparative calorimeter (LGCC) that was operated under quasi-steady state conditions during the cooling/heating process. The results confirmed that PCMs can be steadily absorbed in LWAs without chemical reactions or great losses in latent heat when the LWA-PCMs were coated in a certain way. Cement paste was recommended to coat the surface of the LWA-PCMs for better compatibility with the system than that of traditional coating materials. The ability of the PCM to delay or prevent ice formation in mortar was verified from the exothermic/endothermic events associated with the phase transformations of the pore solution and PCM. In the present study, when up to 50% vol. of the LWA was replaced as carriers of PCM, the heat released by the PCM was sufficiently high to inhibit ice formation. [ABSTRACT FROM AUTHOR]

In this work, the adsorption of metal ions (Cd(II), Cu(II) and Ni(II)) onto ultrasonic-modified jujube seeds (UMJS) was investigated in a batch mode system. The synthesized UMJS was analyzed using scanning electron microscopic and X-ray diffraction analyses to predict the adsorbent quality. The optimum condition for metal ions adsorption in the studied system is as follows: adsorbent dose = 2.4 g/L Cd(II) ions, 2 g/L Cu(II) ions and 3 g/L Ni(II) ions; temperature = 303 K; pH = 5.0; and contact time = 60 min. The two-parameter models (Langmuir and Freundlich) and three-parameter models (Redlich–Peterson and Toth) were used to delineate the removal rate of metal ions by the UMJS. Among tested isotherm models, Freundlich and Redlich–Peterson models produced the best fit (R2 > 0.99) to the adsorption equilibrium data with low error values. Monolayer adsorption capacity of the UMJS for Cd(II), Cu(II) and Ni(II) was found to be 182.4, 259 and 140.9 mg/g, respectively. The thermodynamic results showed that the adsorption process is exothermic and spontaneous in nature. Adsorption kinetic was studied through pseudo-first-order and pseudo-second-order models where pseudo-first-order kinetic produced the best fit. From the results, UMJS can be used as a potential adsorbent for the removal of metal ions from wastewater. [ABSTRACT FROM AUTHOR]

The nitridation-induced self-formed aluminum matrix composite (NISFAC) process is based on the nitridation reaction, which can be significantly influenced by the characteristics of the starting materials (e.g., the chemical composition of the aluminum powder and the type, size, and volume fraction of the ceramic reinforcement) and the processing variables (e.g., process temperature and time, and flow rate of nitrogen gas). Since these variables do not independently affect the nitridation behavior, a systematic study is necessary to examine the combined effect of these variables upon nitridation. In this second part of our two-part report, we examine the effect of nitrogen flow rates and processing temperatures upon the degree of nitridation which, in turn, determines the amount of exothermic reaction and the amount of molten Al in the nitridation-induced self-formed aluminum matrix composite (NISFAC) process. When either the nitrogen flow rate or the set temperature was too low, high-quality composites were not obtained because the level of nitridation was insufficient to fill the powder voids with molten Al. Hence, since the filling of the voids in the powder bed by molten Al is essential to the NISFAC process, the conditions should be optimized by manipulating the nitrogen flow rate and processing temperature.

This paper investigates the effect of the size and volume fraction of SiC, along with that of the processing temperature, upon the nitridation behavior of aluminum powder during the nitridation-induced self-formed aluminum composite (NISFAC) process. In this new composite manufacturing process, aluminum powder and ceramic reinforcement mixtures are heated in nitrogen gas, thus allowing the exothermic nitridation reaction to partially melt the aluminum powder in order to assist the composite densification and improve the wetting between the aluminum and the ceramic. The formation of a sufficient amount of molten aluminum is key to producing sound, pore-free aluminum matrix composites (AMCs); hence, the degree of nitridation is a key factor. It was demonstrated that the degree of nitridation increases with decreasing SiC particle size and increasing SiC volume fraction, thus suggesting that the SiC surface may act as an effective pathway for nitrogen gas diffusion. Furthermore, it was found that effective nitridation occurs only at an optimal processing temperature. When the degree of nitridation is insufficient, molten Al is unable to fill the voids in the powder bed, leading to the formation of low-quality composites with high porosities. However, excessive nitridation is found to rapidly consume the nitrogen gas, leading to a rapid drop in the pressure in the crucible and exposing the remaining aluminum powder in the upper part of the powder bed. The nitridation behavior is not affected by these variables acting independently; therefore, a systematic study is needed in order to examine the concerted effect of these variables so as to determine the optimal conditions to produce AMCs with desirable properties for target applications.

Casting is routinely used for acute andpost-operative immobilization and remains a cornerstone in the non-operative management of fractures and deformities. Theapplication of a properly fitted and well-molded cast, especially for a trainee, can bechallenging. We present a simple method ofprolonging cure time of fiberglass cast — placing ice in the dip water. Eight-ply, five-inch fiberglass cast was circumferentially applied to an aluminum-wrapped cardboard cylinder. An electronic, 2-channel temperature sensor (TR-71wf Temp Logger, T&D Corporation, Matsumoto, Japan), accurateto 0.1ºC and accurate to ±0.3ºC, was placed between the fourth and fifth layers of fiberglass. Thirty total casts were tested using 9±1ºC (cold), 22±1ºC (ambient), and 36±1ºC (warm) dip water. Room temperature was maintained at 24±1ºC. Cast temperatures were measured during theexothermic reaction generated by the castcuring. Peak temperatures and cure timeswere recorded. Cure time was defined as the point of downward deflection on the time-temperature curve immediately after peak. Cure and peak temperatures were compared among groups using analysis of variance. Mean cure time was 3.5±0.1 minutes forwarm water, 5.0±0.4 minutes for ambient water and 7.0±0.5 minutes for cold water. Peak temperature, measured between layers 4 and 5 of the cast material, was 36.6±0.8ºC for warm water, 31.1±1.4ºC for ambient water and 25.2±0.5ºC for cold water. Cold afforded, on average, an additional 2 minutes (40% increase) in cure time compared to ambient water and an additional 3.5 minutes (100% increase) compared to warm water. Cure time differences were significant (P

Herein, hybrid polymeric nano-composite (HPNC) was used for manganese metal ions (Mn²+) removal from aqueous solution. Different parameters were used for adsorption tests. The equilibrium studies were confirmed using Freundlich and Langmuir isotherms and the adsorption capacity was calculated to be 162 mg/g for Mn²+ by fitting the equilibrium data to the Langmuir model. The kinetic parameters showed that Mn²+ ions adsorption on HPNC followed pseudo-second-order kinetic model. Furthermore, the negative values of ΔG and ΔH evidence that Mn²+ adsorption on HPNC is an exothermic and spontaneous process in nature. The desorption studies displayed the best recovery of Mn²+ ions in 0.1 M HCl indicating that they can be recycled in industrial processes. Regeneration studies showed 41.40% and 40.26% loss in Mn²+ adsorption and recovery after four consecutive cycles, respectively. These findings suggest that HPNC has the promising application as an effective and economically feasible adsorbent for Mn²+ removal. [ABSTRACT FROM AUTHOR]

Highlights • Intra-particle gas measurements were taken using a Kr tracer. • The process energetics were assessed based on TG, GC and by-product characterization. • Changes in gas, char and liquid were plotted on a Van Krevlin diagram. • Reactions transitioned from endothermic to exothermic near 300 °C. • Reactions transitioned back to endothermic at 460 °C. Abstract The results of birch wood pyrolysis are presented providing details on the gas, liquid and char mass production rates as a function of temperature from 25 °C to 500 °C. Quantitative measurements, using a Kr tracer, were taken from the center of a sphere sample enabling insight into the product gas formation profiles over the same temperature range. A unique calculation methodology was developed to combine data from TG measurements, quantitative GC measurements of the gaseous chemical species and ultimate analysis of the char product enabling the elucidation of the energetics of the pyrolysis process as a function of temperature. Precise calculations based on the measurements of gas, liquid and char production rates demonstrated the pyrolysis of birch wood transitions from endothermic to exothermic conditions at 280 °C. The reactions maintain an exothermic character until 480 °C then return to an endothermic nature at 500 °C. Changes in gas, char and liquid elemental compositions, plotted as a Van Krevelen diagram, indicated as temperature increases char and liquids trend toward lower O/C and H/C ratios. However, the gaseous H/C decreased slightly from 1.7 to 1.45 yet the O/C increased dramatically from 0.3 to 2.0. [ABSTRACT FROM AUTHOR]