Chemically Research Articles

3, 4-Bis (3-nitrofurazan-4-yl) furoxan (DNTF) and 4-methoxy-1-methyl-3, 5-dinitro-1H-pyrazole (DMDNP) based molten carrier with high energy and low sensitivity: eutectic design and desensitization effect

Utilizing insensitive explosives to form a eutectic with 3, 4-bis (3-nitrofurazan-4-yl) furoxan (DNTF) proved to be an effective method for reducing its sensitivity and melting point. In this study, the interaction between DNTF and 4-methoxy-1-methyl-3, 5-dinitro-1H-pyrazole (DMDNP) was simulated using the interaction region indicator (IRI), revealing that the intermolecular forces in the mixture are stronger than those of the individual components. Co-molten mixtures of DNTF-DMDNP with varying compositions were prepared through electrostatic spraying technology, and a binary phase diagram was established using differential scanning calorimetry (DSC). The experimentally extrapolated molar ratio of the DNTF-DMDNP eutectic was determined to be 48.7/51.3, with a eutectic point at approximately 338.2K. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) tests confirmed that no chemical reactions or crystal transformations occurred during the preparation of the eutectic. The thermal decomposition temperatures at different heating rates and apparent activation energy of the eutectic fell within the range between those of DNTF and DMDNP. Addition of even just 10% DMDNP significantly reduced mechanical sensitivity in co-molten mixtures, resulting in a rapid decrease from 100% to 12% friction sensitivity. The detonation velocity of the DNTF-DMDNP eutectic measured at 8.47kms-1 only experienced a slight decrease by about 0.78kms-1 (8.4%) compared to pure DNTF, indicating efficient desensitization by incorporating DMDNP with minimal energy loss potentiality. Furthermore, adjusting composition allowed for control over detonation performance and sensitivity in melt-cast explosives composed of DNTF-DMDNP.

Turbulent spray combustion modeling in reduced tabulation parameter space by similarity mapping

To overcome the modeling challenge from the coupling between liquid vaporization and chemical reaction in turbulent spray combustion, a similarity mapping approach is implemented to reduce the flamelet tabulation parameters. In the framework of Eulerian–Lagrangian multiphase large eddy simulations (LES), such a modelling idea is developed upon the conventional flamelet/progress variable model. The flamelet library is constructed from a series of quasi one-dimensional spray counterflow solutions, integrated with the multiple solution modes. Test cases, including the laminar spray counterflow flame and Sydney turbulent spray flame, indicate that this newly proposed model is in principle favorable to improve the numerical predictability with acceptable computational cost. Overall, the flame structure can be appropriately captured, showing better performance compared with some reported results. Novelty and significance statementA newly proposed similarity mapping spray flamelet/progress variable (SMFPV) model is implemented for turbulent spray combustion. In SMFPV, the number of entry parameters of the flamelet library is reasonably reduced and two-way coupling between flame and evaporation can be realized. Thus in principle, SMFPV is favorable to improve the numerical predictability with acceptable computational cost. Simulation results of test cases justify the modelling idea.

Numerical study of entropy production and EMHD effects in a peristaltic motion of Prandtl fluid with solid particles and porous medium

Particulate-fluid flow involving chemical reactions plays a crucial role in pharmaceutical manufacturing, catalytic converters, and combustion processes. This research focuses on the analysis of mass and thermal transfer, highlighting the influence of electroosmosis and magnetic forces on the flow of Prandtl fluid through a peristaltic porous micro-channel. In addition, the multiphase flow attitude, affected by chemical reactions, is extensively examined. The flow model is formulated by utilizing the lubrication theory estimation, integrating lengthy-wavelength and creeping flow approximation to simplify the considered problem. To further simplify the problem, Debye linearization is used, resulting in a set of two ordinary differential equations. The outcomes indicate that velocity drops with rising magnetic field, while it enhances with the Helmholtz-Smoluchowski velocity coefficient. Furthermore, thermal distribution increases with greater concentrations of solid fragments and greater magnetic field. These findings provide valuable insights into optimizing mass and thermal conveyance in peristaltic problems, with potential appliances spanning numerous industrial and biomedical areas.

Featuring the aspects with temperature dependent viscosity of inclined MHD Williamson fluid along with heat source/sink, Soret and Dufour effects: A predictor-corrector approach

The boundary layer flow analysis of Williamson fluid moving on the stretched cylinder has applications in the polymer processing, drug delivery system, cooling systems, rheology of food products, dyeing, and finishing. The numerical solutions of governing Navier-Stokes equations at different scenarios of thermal and solutal aspects have lots of practical implications, including biomedical engineering, cooling and heating processes, chemical reactors, aerodynamics, environmental science, and thermal storage systems. From these practical applications, the authors were motivated to conduct a study in which the numerical behavior is examined by applying the Adams-Bashforth predictor and corrector approach of numerical analysis for the Williamson fluid model in the presence of varying viscosity, natural convection, and the inclined magnetic field. Furthermore, Joule heating, thermal radiation, and heat source/sink effects are included in the thermal aspects because these are the important concepts in thermal management and engineering and have applications in solar thermal energy systems, combustion engines, heat exchangers, nuclear reactors, thermal imaging, and safety. Apart from thermal aspects, the analysis of mass transfer focuses on the influence of chemical reactions and Soret-Dufour effects. The similarity transformations are adopted to convert partial differential equations into ordinary differential equations. Specifically, the well-known predictor and corrector numerical method named the Adams-Bashforth method in combination with the Runge-Kutta 4th order scheme is used to achieve the numerical solutions. The temperature, concentration, and velocity regions are displayed on the graphical and numerical conducts. A comparison is also made between the results obtained by the shooting method and the numerical findings of skin friction, Nusselt number, and Sherwood number determined by the Adams-Bashforth method. The determining results concluded that the restrictions in the flow of Williamson fluid are caused by variations in the inclination magnetic field, the surface curvature, and the Williamson parameter, whereas the motion of the fluid increases due to convection, which occurs due to thermal phenomena. The determined results indicate that the temperature distribution is enhanced due to the addition of thermal radiation, Eckert number, and magnetic field. The surface curvature, Soret number, and reaction coefficient marks the decrease impact on the concentration region. The temperature-dependent viscosity increases the drag force and friction coefficient. The Nusselt number is amplified by applying thermal radiation to the surface of the cylinder. The chemical reaction is the source of the increment in the Sherwood number.

Hemp fibre reinforced natural rubber bio-macromolecule based biodegradable engineered leather

Out of the diverse industrial applications of hemp fibre, for the first time we report the development of a leather alternative (flexible composite) material by integrating hemp fibre, as a bio-reinforcement and natural rubber (latex) macromolecules, as a matrix. For developing such unique product, primarily, hemp fibre was extracted from the Canabinus sativa L., i.e., industrial hemp plant. The structure and physico-mechanical properties of extracted hemp fibre used for making leather alternative were thoroughly studied. Characterization analysis has underscored that the fibre has crystallinity of around 78 % and composed of mainly cellulose, hemicellulose and lignin. Physical properties of fibre denote that hemp is longer, finer, stronger, higher elongation%, than widely available ligno-cellulosic jute fibre. Natural rubber (latex) biomolecule-based formulation was used as matrices, allowing the hemp fibre content in the flexible composite approximately 38–40 %. Developed flexible composite was then hot-pressed and coloured for mimicking with natural leather. Natural fibre-reinforced-leather with areal density of 250–550 g/m2 were fabricated and were characterized in detail in terms of physical, structural, mechanical, and chemical properties. Tensile and tear strength of the developed leather material lies in between 8 and 9 N/mm2 and 90–110 N, respectively. Moreover, different integral parts of natural rubber based engineered leather were examined by Fourier-Transform-Infrared-Spectroscopy (FTIR), X-ray diffraction (XRD), surface roughness, chemical composition analysis and scanning-electron-microscopy (SEM) techniques to understand the mechanical of interaction among the different component and to suggest the possible chemical reaction among the different macro-molecules, responsible towards good stability of the natural fibre-reinforced-leather structure.

Physiochemical profiling of bioplasticizer derived from Ficus benghalensis leaves for eco-friendly applications

Ficus benghalensis is a tree belonging to the Moraceae family, reaching a height of 20–30 m and featuring branches that spread out widely, along with roots that grow in the air. F. benghalensis leaf cellulose (FBLC) is a type of biodegradable plasticizer with a restricted range of uses. Using pyrolysis and chemical reactions, this research aimed to produce a biodegradable plasticizer from natural sources. Once extracted, microscopic investigations evaluated the plasticizer’s suitability for use in lightweight packaging. The prominent Fourier transform infrared peaks ranging from 644 to 1124 cm−1 indicated the presence of C–Cl and C–F bonds. Additionally, the peak at 1524 cm−1 corresponds to the C–OH stretching in FBLC plasticizer, which is an organic molecule. The thin, downward UV peak indicated the presence of lignin or hemicelluloses. A strong transmission peak was observed at wavelengths of 240 and 366.34 nm. The FBLC plasticizers could be responsible for the size variations seen in the XRD view. The presence of a prominent thermogravimetric analysis (TGA) peak at an angle of 2θ = 28.35° indicated that the plasticizers had a significant enhancement on its crystalline properties. The material exhibits thermal stability up to a temperature of 271 °C. The FBLC plasticizer’s kurtosis (Rku) value ranged from 13.44 to 15.74, with a maximum value of 15.74 generating spikes on the produced surface and a minimum value of 13.44 skewing atomic force microscopy data. Scanning electron microscopy analysis revealed the presence of micro-sized fillers, plasticizers particles, rough surfaces on the fillers, and well-matched rough surfaces. The EDX test confirmed that the FBLC was free from any elemental impurities and showed a high level of purity. The Rq or Rrms value of FBLC surface roughness, measured at 48.28 μm, represented the square root of amplitudes relative to the midline. A significant reduction at 71.76 °C demonstrated the main thermal transition of the biopolymer, also known as the glass transition temperature of FBLC. In summary, the research findings suggested that bioplasticizers are a viable substitute for synthetic chemicals commonly used in the lightweight packaging industry.

Thermal decomposition behavior and kinetic mechanism of waste phosphors during sodium hydroxide roasting

Waste phosphors are critical rare earth secondary resources, and their recycling can help alleviate the depletion of rare earth mineral resources. However, stable Al–Mg spinel structures exist in waste phosphors. The direct acid leaching method remains difficult to use for leaching cerium and terbium. In this paper, the waste phosphors were first pretreated via alkali roasting. NaOH was used as an alkali roasting agent, thus achieving the decomposition of the Al–Mg spinel structure. On the basis of thermodynamic calculations, thermal decomposition experiments were performed. The results showed that when the temperature was greater than 500°C, the waste phosphors could be decomposed into MgO, Eu2O3, Y2O3, CeO2, Tb4O7, NaAlO2, and BaO. The Ce3+ and Tb3+ in the waste phosphors were partially oxidized to Ce4+ and Tb4+, respectively, during the roasting process. The BET surface area and the average pore diameter for the roasted products also increased. Under the conditions of roasting temperature at 900°C, NaOH/sample mass ratio of 2.5, and roasting time of 150min, the leaching efficiencies of Y, Eu, Ce, and Tb could reach 99.4%, 99.1%, 98.5%, and 98.8%. The decomposition process of waste phosphors conformed to the unreacted shrinking core model. In addition, the conversion processes of Ce and Tb depended on the chemical reaction. The results may provide a new direction of development for the resource utilization of waste phosphors.

Dichlorophosphoryl Isocyanate: Synthesis, Chemical Reactions, and Biological Activity of its Derivatives

Abstract: Dichlorophosphoryl isocyanate (DCPI) is the most basic and easy phosphoric isocyanate substrate that introduces organic moieties. Synthesized since 1954, the DCPI has a high reactivity toward primary and secondary alkyl, alcohols, phenols, thiols, and amines via the nucleophilic addition reaction on the carbon atom of the isocyanate group. In addition to their synthesis, the resulting products undergo nucleophilic substitutions of the chlorine atoms. Their reactions with nucleophilic and bi-nucleophile reagents yield acyclic and P-heterocyclic compounds, respectively. The resulting compounds have different potential antibacterial, antifungal, and antitumor activities.

Bioconvection flow of Carreau nanomaterial invoking Soret and Dufour impacts

Background and objectiveThermal transport enhancement through nanomaterial flow has gained much attention of the investigators recently. Such attention is for applications in engineering, petroleum industries, geothermal engineering and pharmaceutical developments such as X-ray imaging, welding process, semiconductor material production, thermal storage system, electric cooling devices, drug delivery, magma solidification etc. In view of such interest here we analyze the bioconvective stretched flow of Carreau nanoliquid. Thermal, microorganism and mass convective constraints are considered. Gyrotactic microorganisms within presence of chemical reaction is considered. Variable thermal conductivity is considered. Dufour and Soret features are under consideration. Thermophoresis diffusion and random movement features are considered. Energy relation comprises heat generation and radiation. MethodologyNonlinear dimensionless expressions are developed by employing suitable transformations. Numerical computations are obtained by implementation of Newton built in-shooting technique. ResultsPerformance of liquid flow, concentration, microorganism field, and thermal field is studied. Numerical values of quantities of engineering performance via influential parameters are explored. Larger Weissenberg number yield velocity increase. Reduction in velocity through bioconvection Rayleigh number is witnessed. Concentration and thermal field through solutal thermal Biot numbers have similar effect. An increment in thermal distribution and Nusselt number for Dufour number is detected. Increasing values of Soret number and chemical reaction correspond to decay in concentration. An augmentation in thermal transfer rate and temperature through radiation is noticed. An increment in density number against Peclet and bioconvection Lewis numbers is noticed.

Effect of cementitious capillary crystalline waterproof material on the mechanical behavior of concrete

Cementitious capillary crystalline waterproof material (CCCW) is a material that can react with substances inside the concrete, generating crystals that fill the pores and cracks in the concrete. This chemical reaction is expected to improve the mechanical properties of the concrete. This study investigated the effects of CCCW content and water-cement ratio (W/C) on the compressive behavior of cementitious capillary crystalline waterproof concrete (CCCWC). The results indicated that as the CCCW content increased from 0% to 1.5% for W/C of 0.4, the compressive and tensile strength values of concrete slightly decreased. This is because excessive CCCW generates too many crystals within the concrete, leading to internal matrix expansion and crack formations. However, in the cases of W/C of 0.45 and 0.5, the compressive and tensile strength values of the CCCWC increased wit increasing CCCW content from 0% to 0.5%, but declined with 1.5% CCCWC addition. The reaction between CCCW and concrete generates numerous crystals, which densify the concrete matrix and enhance its strength. Moreover, with increasing W/C, the CCCWC's compressive strength and tensile strength decreased due to the increased porosity of the concrete matrix and the reduced availability of the concrete constituents that react with CCCW. Furthermore, the appropriate choice of CCCW content and W/C can significantly enhance the slope and peak stress of the stress-strain curve. Based on this, a compressive constitutive model of CCCWC was established. The findings showed that the optimal CCCW content varied with W/C. For instance, for a W/C of 0.4, the maximun compressive strength of 54.82 MPa was achieved without any CCCW addition. In contrast, the addition of 0.5% CCCW to concrete produced with W/C of 0.45 and 0.5 resulted in the highest compressive strengths of 50.98 MPa and 44.90 MPa, respectively.

Analysis of thermal significances of nanofluids in inclined magnetized flow with Joule heating source and slip effects

The growing need for effective thermal management systems in engineering applications will improve performance by using nanofluids. Nanofluids, which show enhanced thermal characteristics compared to typical fluids, offer an effective way for heat transmission processes in industries. This study is particularly useful for systems where traditional fluids are insufficient for improving thermal performance. Understanding the overall impacts of Joule heating, magnetic fields, and slip conditions would be beneficial in fields such as aircraft, microelectronics, and biomedical engineering.The thermal significances of nanofluids in an inclined magnetized flow are analyzed in this work, taking slip effects and the Joule heating source into account. The motivation behind the current research is to investigate the flow and heat transfer behavior of magnetohydrodynamic (MHD) nanofluid under the influence of Joule heating in the presence of slip conditions.Based on conservation laws and suitable boundary conditions, the governing formulas for mass, momentum, energy, and nanoparticle concentration are developed. In this thermal investigation, unsteady nanofluid flow in two dimensions via a nonlinear stretched configuration is studied numerically together with an example of a non-uniform heat source. Using similarity transformation, the governing partial differential equation for chemical radiation and slip effects parameters for hydromagnetic flow is transformed into a set of ordinary differential equation (ODE). To solve these equations, a numerical method is applied. This study found that the velocity, mass transfer, temperature, concentration, heat transfer, and skin friction coefficient are significantly influenced by the chemical reaction, radiation parameter, and velocity slip. A graphical representation of the parameters influencing the heat transfer and the velocity changes in calculation is observed.

Melt-Blown Polypropylene Membrane Modification for Enhanced Hydrophilicity.

Melt-blown, an environmentally friendly technique, is widely used to create high-quality non-woven fabrics by extruding molten polymer resins into interlaced fibers. In the realm of biomedical textiles, its unique microstructure makes it ideal for filtration and wound dressings. Our study focuses on modifying the surfaces of polypropylene melt-blown membranes. An effective, one-step, suitable, and reliable method to graft a bioactive polymer, sodium polystyrene sulfonate-PolyNaSS, onto the membranes has been developed. The process involves UV irradiation to initiate direct and progressive growth of NaSS over the surface through radical polymerization. To assess the efficiency of the grafting, techniques like colorimetry, water contact angle measurements, Fourier-transformed infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used. Outcomes related to the grafting were demonstrated by a change in wettability and quantitatively calculated sulfonate groups. Subsequently, grafted PolyNaSS promoted cell adhesion, as evidenced by improved cell morphology. On grafted membranes, fibroblasts exhibited a stretched shape, while non-grafted ones showed inactive round shapes. These findings underscore the chemical and biological reactivity of polypropylene materials, opening exciting possibilities for various applications of melt-blown materials.

Biginelli Reaction: A Multi-Component Type of Reaction and Synthetic Advancement in the Synthesis of Bioactive Dihydropyrimidinone Derivatives

Background: In synthetic and medicinal chemistry, multi-component reactions (MCRs) are considered an essential tool in synthesizing bioactive heterocyclic scaffolds. These reactions have been strategically used in drug discovery and development because of ease and economy. Objective: The current manuscript aims to highlight the importance of the Biginelli reaction in the synthesis of diverse dihydropyrimidinones with medicinal applications. Methods: We searched various keywords, including “multicomponent reaction”, “Biginelli reaction” and “dihydropyrimidinone” on “PubMed, PubChem, and google scholar” and collected the relevant articles for including the current work. Results: Biginelli reaction involving ketoester, aldehyde, and urea is a high-yielding, atomeconomical, environmentally benign reaction for developing a library of new dihydropyrimidinones to drive the process of drug discovery. Several developments were achieved with modifications of synthetic techniques, including C-H activation, coupling, cycloaddition, etc. Inclusively, these modifications give access to a wide range of dihydropyrimidinones. Conclusion: The current review provides an overview of recent developments in the Biginelli reaction and insights into synthesizing bioactive dihydropyrimidinones.

Providing a new route for chemical recycling of plastics by aspen plus simulation, energy, and its carbon dioxide emissions analysis

In this research, a new complex is proposed for chemical recycling of plastic. After determining the plastic waste entering this process, the sections in which chemical reactions occur have been simulated through aspen plus, such as: gasification of plastic waste and purifying, methanol production, methanol decomposition to various chemicals such as ethylene, propylene, and methane, separation processes for these products, methane decomposition to benzene and the separation of the products of this part, single-step production of styrene from benzene and ethylene, and the polymerization processes. Furthermore, the impacts of this complex on issues such as plastic recycling, energy consumption, and carbon dioxide emissions are studied and compared to conventional methods of plastic production. Results indicate that plastic waste recycling will be more than 98% in the proposed model. Energy consumption is decreased by 29%, carbon dioxide in this part is decreased by 53% by using renewable energy for its power consumption. These results show the sustainability, and circularity of the proposed model.

Sustainable polyurethane biocomposite foams by improved microstructure, acoustic characteristics, thermoregulation performance and reduced CO2 emission through phase change material integration

In this research, phase change material (PCM) comprised of energy storage biocomposite materials were improved with raw materials obtained from renewable resources. Modified raw material was synthesized by epoxy castor oil (ECO). After mixing the obtained modified castor oil (MCO) and polyether polyol, PCM of capric acid (CA) was supplemented. To initiate the chemical reaction, a certain amount of methylene diphenyl diisocyanate (MDI) was added to the mixture to provide cross-linking. The physical and chemical properties of the resulting biocomposite foams (BCF) were characterized. According to the results obtained, mixing MCO into polyether raw material increased the number of closed pores in BCF resulting in more CA stored in BCF cells produced. The use of MCO in BCF materials increased the CA integration ratio to 68 wt%. The melting enthalpy value of the novel BCF-PCM composites has been determined as 121.43 J/g. In a warm environment, the PCM additive creates a temperature difference exceeding 6 °C, while in a cold environment, it provides a cooling effect close to 6 °C. A more than 50 % improvement in thermal conductivity was achieved with 68 wt% PCM addition compared to pure BCF. The addition of PCM caused a reduction in tensile stress and strain values to an acceptable level. BCFs with PCM additives exhibit a sound absorption coefficient of 0.9 in narrow frequency ranges, whereas, in broad frequency ranges, this value was more than 0.7. In cold weather conditions, employing BCF-PCM material instead of traditional EPS material with a thickness of 0.1 m has led to at least a 30 % drop in CO2 emissions, no matter the type of fuel used for heating. When opting for BCF-PCM materials, the necessary heat demand was approximately 33 % less compared to using the same thickness of EPS in cold climates.

CeO2/NH2-MIL-88B(Fe) composites with peroxidase-like activity for colorimetric detection and photo-enzymatic synergetic degradation of ciprofloxacin hydrochloride

Photocatalysis combined with enzyme catalysis for wastewater treatment is now a promising and challenging process. Therefore, it is necessary to synthesize a material with both photocatalytic and enzyme-catalyzed functions. CeO2/NH2-MIL-88B(Fe) composites with peroxidase-like activity (referred to as CNF-X, where X is the molar ratio of Ce to Fe) were prepared using a solvothermal method. The composites can be used for colorimetric detection, the limit of detection (LOD) was 0.029µM in the range of 50-200µM of ciprofloxacin hydrochloride (CIP). Using a combination of photocatalytic and enzymatic reactions, light excites enzyme activity to achieve highly efficient and selective chemical reactions. In addition, H2O2 activation promotes redox cycling reactions between Ce and Fe, providing more active sites and facilitating photo-enzymatic synergetic catalysis. Under the conditions of 0.01g CNF-5, pH = 3.5, and 25 °C, more than 92.8% of CIP (20mg/L solution) was degraded within 80min, and the photo-enzyme synergistic catalysis mechanism was examined. The stable enzymatic activity and good reusability of the material were confirmed by cycling experiments and X-ray diffraction (XRD) patterns before and after the reaction. The contribution ratio of radicals and non-radicals in the degradation of CIP was analyzed. Density functional theory (DFT) calculation was applied to predict possible degradation pathways. Simulation results stemmed from Toxicity Estimation Software Tool (T.E.S.T) showed an overall reduction in the toxicity of the intermediates. This study provides important application value and theoretical guidance for peroxidase-like materials in environmental detection and remediation.

Multiple effects of high efficiency solid inertants on fire hazard of the accumulated Mg dust layer

Due to low melting and boiling points and extreme reactivity in the chemical reaction of Mg powder, inert powders that have a significant inerting effect on Mg dust clouds can cause significant combustion enhancement of the accumulated Mg dust layer. To circumvent this unforeseen fire hazard, this research selects five types of inertants that have been demonstrated to exert an inerting effect on metal dust clouds and possess a potential flame-retardant effect on Mg dust layers. This research aims to investigate the effect of inert powders on Mg dust layers to identify an efficient inerting mechanism for Mg dust layers. The results indicate that the selection of inertants for Mg dust must be based on a comprehensive evaluation of their physical and chemical properties. The presence of substances with strong decomposition and decomposition products that readily produce gases will destroy the oxide crust on the surface of the accumulated Mg dust layer, thereby causing violent gas-phase combustion. In the case of highly chemically stable substances, the melting point is of primary importance. The formation of cracks in the oxide crust is also a consequence of the higher melting point of inertants, resulting in a combustion enhancement of the mixed dust layer. Inertants with a low melting point and a high boiling point demonstrate a high degree of inerting efficiency for Mg dust layers. The melting of the inert substances forms a liquid film, which prevents the Mg powder from coming into contact with the air surrounding and within the combustion zone. The results of this research are both instructive and valuable for preventing explosions in the process industry involving metal dust materials.

Carbon dioxide capture in sodium carbonate solution: Mass transfer kinetics and DTAC surfactant enhancement mechanism

Sodium carbonate solvent absorbent has been widely studied for CO2 reduction to deal with global warming because of its green, low cost, and non-corrosive advantages. However, in the application of sodium carbonate as an absorbent for CO2 capture, there is no unified cognition of the mass transfer process, which leads to the lack of guidance for the industrial large-scale process. Moreover, the mechanism of mass transfer enhancement of surfactants, which can effectively improve the mass transfer performance, has not been effectively explored in the literature. Based on this, this paper firstly adopts the molecular dynamics method to analyze the solution characteristics after surfactant addition and optimize the surfactant. Subsequently, a classical dissolved oxygen test method was used to measure the gas-liquid mass transfer coefficient for CO2 absorption into sodium carbonate solution. And based on this mass transfer coefficient measurement method, the mass transfer process of sodium carbonate solution with surfactant was analyzed. The results showed that the sodium carbonate solution with 5 wt% concentration and 10 wt% concentration at 30 °C did not satisfy the pseudo first-order fast chemical reaction kinetics assumption. To improve CO2 absorption mass transfer rate, dodecyl trimethyl ammonium chloride (DTAC) surfactant was introduced, which was improved by 119 % compared with non-enhanced solvent at 5 wt% concentration solution, and the assumption of pseudo first order fast chemical reaction was satisfied. After the introduction of surfactant, the barrier effect decreased the liquid phase mass transfer coefficient, but the Marangoni effect happened in the 5 wt% concentration of sodium carbonate solution, which enhanced the liquid-phase mass-transfer coefficient. This finding reveals the mechanism of mass transfer promotion of sodium carbonate by the surfactant DTAC, which is of great engineering significance for the application in the field of decarbonization after the introduction of surfactant.

Co-firing characteristic prediction of solid waste and coal for supercritical CO2 power cycle based on CFD simulation and machine learning algorithm

The co-firing technology of combustible solid waste (CSW) and coal in the supercritical CO2 (S-CO2) circulating fluidized bed (CFB) can effectively deal with domestic waste, promote social and environmental benefits, improve the coal conversion rate, and reduce pollutant emission. This study focuses on the co-firing characteristics of CSW and coal under S-CO2 power cycle, and simulations are conducted by employing Multiphase Particle-in-cell (MP-PIC) method integrated with the comprehensive chemical reaction models in a 300 MW S-CO2 CFB boiler. Effects of operating parameters including fuel mixture proportion and first stage stoichiometry on the gas emission characteristics are further analyzed. Based on training and testing database based on the simulation results, a novel Improved Whale Optimization Algorithm and Bi-dictionary Long Short-Term Memory (IWOA-BiLSTM) algorithm model is established to predict CFB temperature, NOx emission concentration, and SO2 emission concentration, respectively. Results show that CO and SO2 decrease with the coal mass ratio of the fuel mixture increasing, while NOx increases. With the increase of first stage stoichiometry, CO increases, NOx declines, and the change of SO2 is not obvious. Compared with two other basic algorithm models, the prediction error of the proposed algorithm model for the three targets is minimal with the average relative error of 0.032 %, 0.231 %, and 0.157 %, respectively, which can meet the prediction requirements with acceptable accuracy.

Computer-assisted discovery of tyrosinase inhibitors from turmeric and clove: An in silico study on natural skin whitening agents and their potential toxicity

A computational approach was employed to identify potential tyrosinase-related protein 1 (TYRP1) inhibitors from turmeric and clove extracts, with the goal of discovering safer alternatives to the toxic hydroquinone for skin whitening applications. Gas Chromatography–Mass Spectrometry (GC–MS) analysis revealed the phytochemical composition of the plant extracts, which were then evaluated for their binding affinity to TYRP1 through molecular docking simulations. The stability of the resulting hit compounds was assessed via molecular dynamics simulations, and their dermal toxicity profiles were determined using Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) analysis. Density Functional Theory (DFT) calculations were also performed to compare the chemical reactivity of the hit compounds to hydroquinone. The results identified 3,4-dimethoxybenzamidoxime from clove and Ar-turmerone from turmeric as potential inhibitors, exhibiting binding free energies of −6.8 kcal/mol and −6.6 kcal/mol, respectively. These values surpass those of hydroquinone (−5.1 kcal/mol) and the native ligand (−5.5 kcal/mol), suggesting potential inhibitory activity. Notably, 3,4-dimethoxybenzamidoxime exhibited favorable skin permeation properties and passed all toxicity tests, suggesting its potential as a safe and effective replacement for hydroquinone in skin whitening products.