Exothermic Research Articles

Fabrication of sulfur-based functionalized activated carbon as solid phase extraction adsorbent for selective analysis of selenite in water

Based on the important feature of sulfur with excellent selectivity toward selenite in the presence of selenate, a simple and low-cost adsorbent of solid phase extraction known as sulfur loading activated carbon (SAC-6) was successfully prepared and applied for selenite (Se(IV)) analysis in water. Microstructure and morphological characteristics of SAC-6 had been identified by XRD, TEM, BET and FT-IR. In the static adsorption experiments, Se(IV) could be separated in a wide range of pH values (pH=3–11). The retention process of Se(IV) onto SAC-6 was characterized as spontaneous exothermic reaction. An obvious change of adsorption mechanism occurred in static and dynamic adsorption processes shown that the behaviors followed monolayer and hybrid adsorption. The theoretical maximum adsorption capacity of SAC-6 calculated by Langmuir-Freundlich was 13.48 mg/g. The microcolumn filled with SAC-6 was applied to extract Se(IV) in water solution. The detection limit of Se(IV) analytical procedure was confirmed as 0.27 μg/L within a linear range of 10–1000 μg/L. A good precision with relative standard deviation of 1.34 % (100 μg/L, n = 6) was achieved. The high adaptability and accuracy of SAC-6 microcolumn was validated by analyzing natural water samples and certified reference materials. Our work successfully excavated the application value of the sulfur selectivity, and also provided a new adsorbent for Se(IV) extraction and analysis.

Effect of environmental factors on adsorption of ciprofloxacin from wastewater by microwave alkali modified fly ash

Antibiotics, as emerging persistent pollutants, pose significant threats to human health. The effective and low-cost removal of ciprofloxacin (CIP) from wastewater has become an important research focus. In this study, fly ash (FA) was used as the raw material, and modified fly ash (MFA) was prepared by varying microwave power, alkali concentration, and immersion time to investigate its adsorption characteristics for CIP. Results showed that the optimal preparation conditions for MFA with the most effective adsorption of CIP, using the Box-Behnken response surface methodology, were a microwave power of 480 W, an alkali concentration of 1.5 mol/L, and a modification time of 3 h. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analyses revealed that after modification, the glassy structure of FA is destroyed, the specific surface area is increased, and obvious hydroxyl O–H absorption peaks appear. Both FA and MFA exhibited adsorption processes for CIP that conformed to pseudo-second-order kinetics and the Langmuir equation. Maximum adsorption of CIP (9.61 and 12.67 mg/g) was achieved at pH = 6. With increasing temperature, the adsorption capacity of both FA and MFA for CIP decreased, indicating an exothermic process. The adsorption capacity of CIP decreased with increasing ion concentration, with the impact order of ions being Al3+ > Ca2+ > Na+. The results show that pore filling, electrostatic interaction, ion exchange and complexation are the main ways of CIP adsorption by FA. Microwave alkali modified fly ash is an economical and efficient adsorbent for CIP removal in water, realizing the purpose of “treating waste with waste”. This study provides a scientific basis for controlling CIP treatment in wastewater.

Copper supported Dowex50WX8 resin utilized for the elimination of ammonia and its sustainable application for the degradation of dyes in wastewater

To obtain high efficient elimination of ammonia (NH4+) from wastewater, Cu(II), Ni(II), and Co(II)) were loaded on Dowex-50WX8 resin (D-H) and studied their removal efficiency towards NH4+ from aqueous solutions. The adsorption capacity of Cu(II)-loaded on D-H (D-Cu2+) towards NH4+ (qe = 95.58 mg/g) was the highest one compared with that of D-Ni2+ (qe = 57.29 mg/g) and D-Co2+ (qe = 43.43 mg/g). Detailed studies focused on the removal of NH4+ utilizing D-Cu2+ were accomplished under various experimental conditions. The pseudo-second-order kinetic model fitted well the adsorption data of NH4+ on D-Cu2+. The non-linear Langmuir model was the best model for the adsorption process, producing a maximum equilibrium adsorption capacity (qmax = 280.9 mg/g) at pH = 8.4, and 303 K in less than 20 min. The adsorption of NH4+ onto D-Cu2+ was an exothermic and spontaneous process. In a sustainable step, the resulting D-Cu(II)-ammine composite from the NH4+ adsorption process displayed excellent catalytic activity for the degradation of aniline blue (AB) and methyl violet 2B (MV 2B) dyes utilizing H2O2 as an eco-friendly oxidant.

The Electrochemical Peroxydisulfate-Oxalate Autocatalytic Reaction.

Aqueous solutions containing both the strong oxidant, peroxydisulfate (S2O82-), and the strong reductant, oxalate (C2O42-), are thermodynamically unstable due to the highly exothermic homogeneous redox reaction: S2O82- + C2O42- → 2 SO42- + 2 CO2 (ΔG0 = -490 kJ/mol). However, at room temperature, this reaction does not occur to a significant extent over the time scale of a day due to its inherently slow kinetics. We demonstrate that the S2O82-/C2O42- redox reaction occurs rapidly, once initiated by the Ru(NH3)62+-mediated 1e- reduction of S2O82- to form S2O83•-, which rapidly undergoes bond cleavage to form SO42- and the highly oxidizing radical SO4•-. Theoretically, the mediated electrochemical generation of a single molecule of S2O83•- can initiate an autocatalytic cycle that consumes both S2O82- and C2O42- in bulk solution. Several experimental demonstrations of S2O82-/C2O42- autocatalysis are presented. Differential electrochemical mass spectrometry measurements demonstrate that CO2 is generated in solution for at least 10 min following a 30-s initiation step. Quantitative bulk electrolysis of S2O82- in solutions containing excess C2O42- is initiated by electrogeneration of immeasurably small quantities of S2O83•-. Capture of CO2 as BaCO3 during electrolysis additionally confirms the autocatalytic generation of CO2. First-principles density functional theory calculations, ab initio molecular dynamics simulations, and finite difference simulations of cyclic voltammetric responses are presented that support and provide additional insights into the initiation and mechanism of S2O82-/C2O42- autocatalysis. Preliminary evidence indicates that autocatalysis also results in a chemical traveling reaction front that propagates into the solution normal to the planar electrode surface.

Preparation of Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles and their adsorption mechanism of methyl blue

A facile rapid-combustion process was introduced for preparing magnetic Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles, and to enhance their specific surface area and saturation magnetization, the optimization involved adjusting the element proportion, calcination temperature, and solvent amount. The optimal element proportion of x:y:(1-x-y) for Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles was 0.1:0.7:0.2, and the effects of solvent amount, and calcination temperature were also investigated. The average particle size and specific surface area of Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles calcined at 400 °C with 25 mL absolute alcohol were 17.9 nm and 56.96 m2/g, respectively; while demonstrating a saturation magnetization of 8.5 emu/g. To solve the increasingly severe issue of water pollution, these nanoparticles were employed to efficiently treat dye wastewater containing methyl blue (MB). After fitting kinetic and isotherm models, the adsorption process of magnetic Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles for MB dominated by chemisorption and was a multilayer adsorption process. The adsorption isotherm experiments revealed a remarkable maximum adsorption capacity of methyl blue, reaching 2255.7 mg/g, within the concentration range of MB from 400 to 4000 mg/L. The thermodynamic analysis indicated the spontaneity of the exothermic adsorption process. The studies on the effect of pH also led to satisfying results; while the residual adsorption capacity could still remain 91.2% initial adsorbance after 12 times recycle. The outstanding recycling ability, resistance to ionic strength, and pH resistance distinguished the magnetic Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles among vast adsorbents. These results highlight the significant potential of these nanoparticles for treating dye wastewater.

Optimizing rotary kiln operations for molybdenite concentrate oxidation roasting to produce molybdic trioxide

The effects of the rotational speed (0–10 rpm) and temperature (550–650 °C) of rotary kiln drums on the oxidation roasting of molybdenite (MoS2) concentrate was investigated in this study. Computational predictions indicated that production of MoO2 was more favorable than that of MoO3 up to a certain stage of the oxidation roasting process, after which MoO3 is produced through the consumption of MoO2. Thus, understanding the MoS2–MoO2–MoO3 relationship and its equilibrium is important. A drum rotational speed > 5 rpm significantly increased the S reduction rate and considerably decreased the S content at 60 min to < approx. 5 %. Additionally, the S content at 60 min decreased with decreasing the temperature from 650 to 550 °C due to the MoS2 concentrate exothermic reaction during oxidation roasting. The MoS2 to MoxOy (≈ MoO2+MoO3) conversion rate (%) was generally proportional to the rotational speed and reaction duration. X-ray diffraction analysis indicated that 5–10 rpm and 550–600 °C yielded a higher experimental conversion rate (97–98 %). Furthermore, the MoO2 and MoO3 conversions were separately quantified. Agglomeration was more pronounced without drum rotation and at higher temperatures. Analysis of the reaction kinetics using the unreacted-core model indicated that diffusion through the gas film layer is supported by the 20.9 kJ/mol activation energy obtained from the Arrhenius plot. Consequently, an appropriate drum rotational speed at a relatively low temperature is a prerequisite for producing MoO3 through the oxidation roasting of MoS2 concentrates in a rotary kiln.

The improvement of heat transfer using Co/SiO2 spiral structured catalyst for green diesel production by Fischer–Tropsch synthesis

In this study, the improvement of heat transfer was applied to eliminate hotspots of a highly exothermic reaction, Fischer–Tropsch synthesis (FTS), by means of two facile methods: (I) adding high thermal conductive materials media diluted in catalysts (SiC and Al chips), and (II) using structured reactors equipped with well-designed structured catalysts with advantages of heat dissipation/removal. The 20%Co/SiO2 catalyst powder prepared by simple impregnation was employed for constructing structured catalysts and granular packed bed catalysts. The structured catalyst was prepared by coating method of Co/SiO2 slurry on an aluminum spiral and plate substrate. The catalytic performance of as-prepared catalysts was then tested for FTS in a fixed-bed reactor at 210–230 °C, 20 bar. Both gaseous and liquid products were collected and analyzed. The heat transfer improvement of packed bed catalytic system and structured catalytic system were compared and discussed. As a result, the structured catalytic system with spiral structured catalyst can provide the best improvement of heat/mass transfer, resulting in enhanced diesel selectivity, though the oil production rate was unsatisfactory. Meanwhile, among the packed bed catalytic systems, SiC media possessed the best heat removal material, producing the highest oil yield. In addition, the fresh and spent catalysts were analyzed by several techniques including TEM, SEM, XRD, BET, ICP-OES, H2–TPR, and TGA to relate the physicochemical properties of the prepared catalysts and its FTS performance.

Insights on the separation process of the diethyl carbonate plant obtained by ethanol and CO2

This paper presents the techno-economics insights of projects of diethyl carbonate (DEC) production from ethanol and CO2 in which the raw materials are proposed to be obtained from existing plants such as the bioethanol industry. The complete DEC plant was simulated using Aspen Plus®. The exothermic reaction system was modeled in multitubular PFR with CeO2 catalyst and dehydrating agent 2-cyanopyridine (2-CP), achieving an EtOH conversion of 86.04 % and a yield of DEC of 83.34 %. Three different configurations were evaluated in the DEC separation stage aiming to intensify the plant with the use of a sidestream distillation column and reactive distillation column. The integration of the DEC plant with ethanol and sugar biorefineries, offering lower-cost acquisition of raw materials, is the key to making the process economically profitable. The process has the potential to capture 0.088–0.204 kg CO2/kg DEC, demonstrating a promising pathway to extend the life cycle of renewable carbon.

Self-ignition behaviour of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification

The possibility of different agrowastes to self-ignite under ambient condition, due to exothermic reactions between their surface molecules and air or other oxidizing agents which are conveyed into the void volume between the particles, exists. It is imperative to investigate the self-ignition ability of these harzadous waste products causing environmental pollution after the milling process to avoid sudden fire outbreaks. In this study, the self-ignition attributes of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification was investigated by evaluating their self-ignition temperatures using DIN EN 15188:2021 standard and Frank-Kamenetzkii's theory of thermal explosion at varying basket volume. The results revealed decrease in the ignition temperature of dust samples as ignition time and dust basket volume were increased. Sample C (rice husk dust residue) was considered to be the most hazardous with respect to its propensity to self-heating possessing the lowest self-ignition temperature of 173 °C at 800 mL cubic mesh. Its moisture content and activation energy of 1.41 % and 46.52 kJ/mol respectively were the lowest. Its thermal conductivity, carbon content, heating value and bulk density of 0.07 W/mK, 78.98 wt%, 26,895 kJ/kg and 255.4 kg/m3 respectively were the highest. Correlation coefficient from the Arrhenius plot showing the self-ignition behaviour of dust samples using the model of Frank-Kamenetzkii were 0.9976, 0.9910 and 0.9962 for corn cob, wheat bran and rice husk residues respectively. In conclusion, the data presented are effective in predicting the self-ignition ability of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification in order to prevent sudden fire attack that may arise based on storage of their dust particles in food processing industries.

Biochar Prepared from Steam-Exploded Bitter Melon Vine for the Adsorption of Methylene Blue from Aqueous Solution: Kinetics, Isotherm, Thermodynamics and Mechanism

Bitter melon vine (an agricultural waste product with high fiber content) is difficult to treat and has caused problems in the environment. This research aims to produce biochar through low-temperature pyrolysis assisted by non-polluting steam explosion. The physical and chemical properties of the biochar were characterized using scanning electron microscopy (SEM) images, specific surface area measurements (BET), X-ray diffraction patters (XRD), elemental analysis (EA), and Fourier transform infrared spectroscopy (FTIR). Next, the adsorption mechanism of methylene blue (MB) on the steam-exploded bitter melon vine biochar pyrolyzed at 200 °C (qBC200) and the effects of adsorption time, pH, initial concentration, adsorption temperature, and adsorbent dosage on the adsorption effect were investigated. Steam explosion destroyed the dense structure of the plant, increased the number of oxygen-containing surface functional groups, and improved the adsorption performance of the material. Therefore, qBC200 more effectively adsorbed MB than untreated biochar, reaching a saturated adsorption capacity of 267.72 mg/g. The MB adsorption kinetics and isothermal adsorption process of qBC200 align with the pseudo-second-order kinetic model and Langmuir isothermal equation (monolayer adsorption), respectively. The thermodynamic results show that MB adsorbs via a spontaneous, entropy-increasing exothermic reaction. The adsorption mechanism involves electrostatic attraction, hydrogen bonding, and π–π interactions. The prepared biomass with high fiber content is a promising new material for wastewater treatment.

Characterization of pristine and aged NMC lithium-ion battery thermal runaway using ARC experiments coupled with optical techniques

Battery thermal runaway (TR) challenges battery applications due to safety considerations, potentially endangering consumers. Understanding the process is crucial to defining first alarm strategies that indicate the risk of TR and designing systems to mitigate this problem. For this reason, the present paper aims to characterise key variables of the venting and thermal runaway processes. Experimental tests were conducted in an accelerating rate calorimeter (ARC) using the heat wait seek (HWS) protocol, which tracks the battery temperature after detecting an exothermic reaction during the seek period. The maximum temperature rise rate and peak temperature that the calorimeter can achieve are 15 °C/min and 300 °C. Two optical accesses in the ARC were modified to use optical techniques such as Schlieren double pass and infrared. The results cover 3 different cell conditions: Pristine cells at state of charge (SOC) 100 %, pristine cells at SOC 50 %, and aged cells at SOC 100 %. For statical purposes, each cell condition was repeated 5 times. The aged battery was cycled to boost solid electrolyte interface growth. The images obtained were post-processed, with a specific methodology for each optical technique, and according to the parameters intended to be obtained. The main result shows that for higher SOC, the exothermic reaction is detected earlier than for SOC 50 %, which was only detected in an advanced TR stage (higher temperature rise rate). Therefore, the battery system capability to detect plays a crucial role in safety. Safety actuation time is reduced by ∼ 40 % for SOC 50 %. However, the energy to manage during this situation is lower (∼42 %), depending on the mass inside the battery, revealing the importance of a good venting cap design. Infrared images have shown higher particle temperatures for higher SOC, about 150 °C higher than the SOC 50 %. The particle velocity, in this case, achieved 30 m/s.

Modelling In Situ Concrete Temperature Development: The Impact of Ambient Temperature and GGBS Replacement

The rise in early-age temperature concrete structures, driven by the exothermic reactions during cement hydration, significantly increases the risk of thermal cracking. To address this issue, the construction industry employs several strategies, including the partial substitution of cement with ground granulated blast furnace slag (GGBS) due to its lower heat of hydration. Accurately predicting the hydration temperature of concrete is critical for preventing thermal cracking. This task becomes more complex, with fluctuating ambient temperatures influencing hydration kinetics and heat dissipation. Previous studies often assume adiabatic or isothermal conditions, thus overlooking the impact of ambient temperature variations. This paper presents an innovative finite element modelling (FEM) approach to simulate the hydration temperature progression in in situ concrete slabs, incorporating the effects of ambient temperature fluctuations. Isothermal calorimetry curves were adjusted using the Arrhenius-based approach to express the cement hydration rate as a function of ambient temperature. The FEM outcomes, validated with semi-adiabatic calorimetry tests, demonstrate the model’s capability to forecast temperature development in in situ concrete under varying ambient conditions. Additionally, the study examines the influence of partial cement replacement with GGBS on thermal behaviour, revealing that while GGBS effectively reduces thermal reactions at higher contents, its efficacy diminishes with rising ambient temperatures.

Instant Synthesis of 2,5‐Diformylfuran from Concentrated 5‐Hydroxymethylfurfural without Catalyst and Organic Solvent

Abstract5‐Hydroxymethylfurfural (HMF) was transformed into 2,5‐diformylfuran (DFF) with nitric acid as the oxidant. The initial HMF content was as high as 12.5 wt %, and water was the sole solvent. This is an intensely exothermic reaction along with the emission of NO2 gas. A high DFF yield of 83.2 % was achieved if the oxidation ability of nitric acid matched with the requirement of target oxidation reaction while mismatched those of side reactions by regulating the initial concentration of nitric acid (59.5 wt %) and reaction temperature (50–60 °C). The oxidation reaction of HMF, overoxidation of HMF, and skeleton‐cracking reaction of FDCA preferred concentrated HNO3, hot HNO3, and concentrated or hot HNO3, respectively. After liquid‐liquid extraction, filtration, and column chromatography, light‐yellow DFF powders with purity of 92.1 wt % and isolated yield of 40.2 % were obtained and confirmed by NMR, FTIR, UV‐Vis, and elemental analysis. HMF was the dominant impurity due to its affinity to DFF. In addition, chromogenic substances were obtained as a byproduct, and they were potential pH indicators. These chromogenic substances had highly conjugated molecular structures, and they were generated via successive β‐protonation‐based ring‐opening reaction of HMF, aldol reaction, and dehydration reaction.

Heterophase Pt/EG-catalyzed hydrosilylation in droplet microfluidics: Spectral monitoring and efficient 3D-printed reactors

Homogeneous Pt-catalyzed hydrosilylation is an industrially important process for the synthesis of organosilanes. Reusable heterophase (biphase) Pt-catalysts can solve economic and ecological issues arising from the high cost of Pt and its irretrievable “scattering”. Previously, we proposed a sustainable and convenient-to-handle heterophase Pt/EG-catalytic system (EG – ethylene glycol). In the current research heterophase Pt/EG-catalyzed hydrosilylation was transferred in a microfluidic regime that combined several advantages. A stable droplet or segmented Taylor flow with a well-defined contact area allow for the improvement of mass and heat transfer during the scaling of such a biphase and exothermic reaction, compared to batch mode. In situ Raman spectroscopy monitoring allows for fast and continuous data collection throughout the experiment and opens an opportunity for automation of conversion analysis. We demonstrate an efficient reaction of a range of reagents in the microfluidic reactor. In this work its universal components were constructed and modified using either commercially available units or via additive technologies (3D-printing). To the best of our knowledge, this is the first example of a semi-automatic recyclization device for a real heterophase catalytic process. These results open up new perspectives for scaling and automating industrially relevant heterophase hydrosilylation reactions.

High-quality mesoporous adsorbent derived from pomegranate pomace for efficient removal of azo dye from textile wastewater: Influencing factors, reusability, and mechanism studies

The solid waste from the processing of pomegranate (Punica granatum L.) juice, known as pomegranate pomace, was utilized as an economical and readily available precursor to produce high-quality activated carbon (AC). The AC was synthesized using a low-cost method at a carbonization temperature of 600 °C, employing a 1:1 impregnation ratio (precursor/H3PO4), and activating for 1 h. Various characterization techniques, including SEM imaging, XRD analysis, FT-IR analysis, BET surface area analysis with pore size determination, and other physicochemical assessments, were conducted on the produced AC. To assess its efficacy in treating textile wastewater, Basic Yellow 28 (BY 28) dye was selected as a representative pollutant. The results displayed a mesoporous structure in the produced AC with a mesopore content of 78.82 %. Notably, it exhibited a high BET surface area of 1089.08 m2/g and a total pore volume of 1 cm3/g. The Langmuir non-linear isotherm model emerged as the most fitting for explaining the adsorption equilibrium data, revealing a substantial monolayer adsorption capacity of 659.13 mg/g at 20 °C. The experimental data fit into a pseudo-second-order kinetic model, where the rate-determining step was found to be intra-particle diffusion. Thermodynamic analysis revealed that the adsorption of BY 28 dye onto the produced AC was an exothermic process. The produced AC exhibited high stability, as demonstrated in desorption studies, maintaining effectiveness through multiple uses. These results signify the potential of using pomegranate pomace, an environmentally problematic waste, as a novel precursor for producing sustainable and cost-effective AC.

Insight into pyrolysis characteristic and mechanism of natural rubber using rapid infrared-heating fixed bed combined with pyrolysis kinetics

Pyrolysis is a potential approach to treat post-consumer waste natural rubber (NR), however, unclear pyrolysis mechanism restricts its actual utilization. In this work, thermal degradation of NR was investigated combining dynamical method with pyrolysis on the infrared-heating fixed-bed reactor. Results show that thermal degradation of NR is an apparently exothermic and multistep reaction, tar yield reaches up to 96.59 wt%. Pyrolysis tar mainly consists of cycloolefin with a small quantity of chain olefins and mono-ring aromatic hydrocarbons. High temperature reduces the cycloolefin yield but promotes the generation of mono-ring aromatic hydrocarbons. Tar is mainly composed of dimer (C10) or trimer (C15) of isoprene with different structures. H type in tar is mainly aliphatic hydrogen. Besides, a possible pyrolysis mechanism based on the β bond breakage was proposed. The work can provide a theoretical basis for direct control of high value-added products during NR pyrolysis and achieve high efficiency pyrolysis of NR.

Advanced overpressure protection: A concept for smart controlled safety pressure relief systems

Safety devices such as safety valves and rupture discs are crucial components in protecting chemical reactors from exothermic runaway reactions and overpressure scenarios. While traditional safety valves operate autonomously, controlled safety devices offer the potential for dynamic adjustments to optimize system performance. However, existing safety valves and controlled safety pressure relief systems (CSPRS) lack flexibility in a fixed relief pressure and stroke positions. This article introduces a new smart overpressure protection device (SmOP) with an adaptable safety device controlled through a combination of model predictive control and PID-control. Tested extensively in a high-pressure loop, the SmOP demonstrates rapid and precise control behavior, ensuring reactor safety as well increasing the efficiency. The control concept, based on model prediction followed by PID-correction, is validated through endurance tests and various opening conditions. Results indicate the SmOP's robustness against external disturbances and its potential for industrial applications. Future work includes developing a failsafe concept and laboratory tests with chemical reactions to further validate the SmOP's performance.

Hydrogen production from photocatalytic water splitting in the hBNC/MoS2 heterojunction: First-principles calculations

Photocatalytic water splitting for hydrogen production is a kind of hydrogen production method with less pollution and low cost. We designed the hBNC/MoS2 heterojunction as a photocatalyst for hydrogen production. This investigation is based on the first-principles. The results show that hBNC/MoS2 heterojunction has type-II band alignment. Moreover, the built-in electric field makes the photo-generated carries transfer along Z-scheme path. The hBNC/MoS2 has suitable band edge positions for hydrogen evolution reaction and oxidation evolution reaction. The reduction reaction overpotential is 2.27 eV (χH2 = 2.27 eV) in hBNC/MoS2. Meanwhile, the visible light absorption is improved in this heterojunction compared with the monolayer hBNC and MoS2. In addition, the Gibbs free energy calculation confirmed that the HER under the light irradiation in hBNC/MoS2 is an exothermic and spontaneous process. This investigation indicates that the hBNC/MoS2 heterojunction has potential application prospect in photocatalytic hydrogen production.

Comparative analysis of kinetic-free thermal runaway criteria for semi-batch isoperibolic homogeneous exothermic reaction

Comparative analysis of kinetic-free thermal runaway criteria for semi-batch isoperibolic homogeneous exothermic reaction

Inclusion complexes of α-cyclodextrin with p-aminobenzoic acid and nicotinic acid: Crystal structure, DSC and IR spectroscopy analysis in solid state and 1H NMR and ITC calorimetric studies of complexation in solutions

In this work, inclusion complexes of α-cyclodextrin with p-aminobenzoic acid (PABA) and nicotinic acid (NIK) were studied. Solid-state complexes were obtained and studied with single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, and FT-IR spectroscopy. Additionally, the formation of complexes was studied in aqueous solutions with isothermal titration calorimetry and 1H NMR spectroscopy in DMSO‑d6 solutions. Single crystal studies, FT-IR spectroscopy and powder diffraction confirmed the inclusion of PABA and NIK inside the cyclodextrin cavity. From the results of the isothermal titration calorimetry, the stoichiometry (n) and standard thermodynamic functions (ΔH, ΔG, ΔS) of complexation, as well as binding constants (K) for the formed complexes were calculated. The obtained results confirmed the thermodynamically spontaneous formation of complexes in exothermic reactions. Furthermore, the results obtained were compared for complexes of PABA/NIK acids with β-cyclodextrin. A database survey of α-cyclodextrin complexes with different benzoic acids available in the CSD database was performed.