Asia-Pacific Journal of Chemical Engineering最新文献

The objective of the current research is to characterize the thermal performance in micropolar fluid flows on a vertically elongated porous sheet in the presence of buoyancy forces. Thus, the motivation of this study is to improve the understanding of buoyancy-driven micropolar fluid flows through porous media, which are relevant to advanced applications such as biofluid dynamics, polymer processing, electronic cooling, and energy systems. The additional physical aspects include the presence of a nonuniform heat source/sink, and the fluid flows across a porous medium under convective boundary conditions. The mathematical problem is nondimensionalized using the similarity transformation approach as a coupled set of ordinary differential equations derived from the governing partial differential equations. The transformed standard ordinary differential equations are subsequently solved using the Runge–Kutta fourth-order method, along with the shooting technique, to evaluate the numerical findings of dependent quantities of physical importance through MATLAB. The impact of varied parameters on fluid momentum, angular momentum, and energy was analyzed and shown graphically. The results show that augmentation of the Grashof number creates a significant boost in the flow velocity, depicting the strength of thermal buoyancy in driving fluid motion. The microrotation field is seen to be strongly affected by the micropolar term, showing that microstructural fluid plays a leading role in angular momentum transport. A larger Biot number improves the surface heat transport rate, as confirmed by a boosted Nusselt number. The streamline patterns show that magnetic fields pointedly reshape the flow regime by damping the boundary layers and changing streamline curvature.

Water pollution due to hazardous dyes is a severe issue that requires investigation through sustainable and cost-effective approaches. In the current scenario, biochar, a carbon-rich material derived from biomass, has found significant importance as an alternative to traditional adsorbents like activated carbon. The wastewater treatment efficacy depends on the structural properties of biochar, such as porosity, surface functional groups, and its mechanism, including physical adsorption, ion exchange, and electrostatic attraction. The current review explores various biochar activation methods, including physical (steam and gasification), chemical (acid, base, oxidant, and salt), and biological (bacterial, fungal, and enzymatic), which are used to increase the adsorption efficiency. However, large-scale production of activated biochar faces many challenges related to quality and sustainability. The application of artificial intelligence (AI) and machine learning (ML) presents new opportunities for optimizing activation parameters and improving predictive modelling. Furthermore, adopting a circular economy approach through biochar reuse in soil remediation, energy recovery, and industrial interdependence can enhance sustainability. Despite promising advancements, research gaps remain in standardizing activation protocols, ensuring long-term stability, and developing policy frameworks for large-scale implementation. Addressing these challenges is critical for advancing biochar as a viable solution for dye removal in wastewater treatment.

The valorization of agricultural pod wastes into biochar offers a sustainable pathway for waste management and the development of functional carbonaceous materials. This study comparatively evaluates biochars produced from cocoa, flamboyant, and locust bean pods using an autothermal top-lit updraft gasifier with retort heating, a system designed to enhance efficiency in low-resource settings. The novelty of this work lies in providing the first comparative baseline data on unmodified pod-derived biochars synthesized under the same controlled gasification conditions. The results show that cocoa pod biochar exhibited the highest yield and superior textural properties, with a surface area exceeding 750 m²/g, while flamboyant and locust bean pod biochars displayed lower but comparable performance. Thermal analysis confirmed stability up to 250°C, while spectroscopic and microscopic characterizations revealed carbon-rich structures with oxygenated functional groups, porous morphology, and embedded mineral elements. These features suggest broad applicability in adsorption, soil amendment, and catalysis, although application trials remain a direction for future studies. In conclusion, this research establishes a reference for pod-based biochars and demonstrates the feasibility of simple, eco-friendly gasification systems for biomass valorization, contributing to the circular economy and sustainable materials development.

Direct preparation of coal–water slurry using coal chemical wastewater represents an economical and feasible approach for wastewater resource utilization. Unlike clean water, however, the complex organic components in wastewater may exert adverse effects on slurry properties. To explore the mechanism underlying the influence of organic components in coal chemical wastewater on the adsorption characteristics of additives onto coal surfaces, address the issue of slurry property variations arising from slurry preparation with different wastewaters, and verify the technical and economic feasibility of wastewater-based coal–water slurry preparation, this study integrated isothermal adsorption experiments with molecular dynamics (MD) simulations. With deionized water as the control group, the study systematically analyzed the effects of four typical organic pollutants, namely, quinoline, phenol, acetic acid, and 5-hydroxymethylfurfural (5-HMF), on the “coal-additive” adsorption system, while comparing the economic performance of preparation strategies in the context of coal–water slurry production lines. The results demonstrated that the Langmuir model (with a fitting deviation of < 6%) and ΔG⁰_ads (all negative values) confirmed the spontaneous nature of the adsorption process. The order of additive adsorption capacity and system interaction energy was determined as quinoline > deionized water > acetic acid > phenol > 5-HMF, where quinoline promoted adsorption whereas the other three components exhibited inhibitory effects. MD simulations revealed that the interaction between coal and additives in deionized water was primarily dominated by van der Waals forces. Organic components reduced electrostatic repulsion but caused a more significant weakening of van der Waals forces, and monolayer adsorption was identified as the optimal microscopic configuration for additives to exert their functional effects—this conclusion was consistent with analyses of adsorption configuration, molecular density distribution, and mobility. Economic analysis indicated that when comparing the two strategies of “adjusting additive dosage” and “ozone oxidation pretreatment,” and taking into account the environmental benefits of wastewater treatment, coal–water slurry preparation using coal chemical wastewater could achieve significant positive benefits under appropriate strategies compared with the conventional method, thereby realizing a win-win scenario for both wastewater treatment and economic gains. This study clarifies the regulatory mechanism of organic components in wastewater on additive adsorption from both macro- and micro-dimensional perspectives, confirms the technical and economic feasibility of coal chemical wastewater-based coal–water slurry preparation, and provides crucial support for advancing the coordinated development of industrial wastewater resource utilization and clean production.

In industrial practice, fats and oils that contain triglycerides when subjected to high-temperature and high-pressure aqueous hydrolysis, yield sweet water as the bottom product and fatty acid mixtures as the top product in a separating column. Though recovery of glycerol from sweet water (15% mixture of glycerol) is well established, purification of fatty acid components is still under research in oleochemical industries. Separation of fatty acids can be effectively accomplished using the crystallization technique. The challenges underlying this study are the ease of separation and crystallization due to the presence of interacting fatty acids having varying melting points and solubility properties. Fractional crystallization with urea is attempted for the effective separation of FA from tallow hydrolysis. The present technique treasures the eco-friendly and green features of the separation of soluble and insoluble contaminants from the crude mixtures in a single phase. Experimental studies reveal that it is feasible to separate certain fatty acids from a crude fatty acid mixture such as myristic, palmitic, stearic, oleic and linolenic with added value. A mathematical model based on the Population Balance Equation is formulated and solved describing the development of crystal size distribution (CSD) in crystallizer in order to predict the resulting particle size distribution, estimate the parameters of the kinetic model and optimize the process conditions to obtain a desired particle size distribution.

The growing need for enhanced thermal regulation is vital in recent advancements such as biomedical engineering, polymer processing, etc. In particular, the non-Newtonian fluid likely Casson fluid with yield stress is used in these areas because of its ability to prepare biofluids and industrial suspensions effectively. The proposed analysis explores the magnetohydrodynamic (MHD) stagnation point flow of Casson fluid via an expanding surface for the impact of dissipative heat and chemical reaction. The heat transport phenomenon is enhanced for the combined impact of Joule dissipation and thermal radiation for the assumption of the Rosseland approximation. The analysis presents its vital role for the introduction of velocity slip and convective heating boundary conditions. Moreover, the modeled problem for the integration of above-mentioned forces is characterized by the use of the similarity rule, which develops the role of diversified factors on the flow phenomena. To execute the physical behavior of the factors involved in the model, first of all, a standard numerical method, i.e., shooting associated with Runge–Kutta fourth-order, is employed utilizing a built-in bvp4c function in MATLAB. In connection with the study reported earlier, the present result is compared and validated with the numerical result in particular cases. Further, the important outcomes of the study are the enhanced non-Newtonian Casson parameter that retards the velocity profile, and the heat transfer rate is also controlled by the increasing thermal radiation, whereas the Eckert number favors a significant enhancement in the heat transfer rate.

With the advancement of the modernization and intensification of urban pipelines, the utility tunnels have become important public infrastructure in the new urban areas of our country. In case of a gas explosion accident, it will seriously endanger public safety. To reveal the mechanism of the collaborative effect of water mist and porous slip device on explosion characteristics, an experiment was conducted on the impact of the collaborative inhibition device on the explosion. The influence of the device on methane explosion pressure, flame propagation speed, and flame luminance was analyzed. The results show that both the sliding device and the water mist can effectively attenuate the explosion flame and reduce the pressure peak. The inhibitory effect decreases as the porosity and elastic coefficient increase. Under the optimal parameter combination (60 PPI, 12.97 N/m), the flame propagation speed is reduced by 84% and the overpressure peak is reduced by approximately 46.51%. In addition, the water mist suppresses the backflow combustion within the porous medium and releases the upstream pressure. At the same time, the physical effect of the water mist and the chemical effect of the sliding device work together to intensify energy dissipation. Furthermore, this study also established a quantitative prediction model to analyze the relationship between the physical parameters of the device and its performance. The multiple regression model analysis further revealed the response mechanism of the composite suppression device in the initial stage of the explosion and the energy attenuation phase, providing a theoretical reference for explosion protection technology.

This study presents a simplified thermal model to analyze the surface temperature variation of a 2.5 Ah 18650 lithium-ion cell under different ambient temperatures and discharge currents (5 and 10 A), considering both open and closed environments. Experimental simulations reveal that in open environments, ambient temperature changes measured at a distance of 1 m have a negligible effect on cell surface temperature, with deviations below 0.11%. However, in closed environments with measurements taken just 3 mm from the cell, the surface temperature rises significantly by approximately 8.75 K at 5 A and 15.75 K at 10 A, indicating restricted heat dissipation and increased thermal buildup. These findings confirm that higher discharge currents and enclosed conditions exacerbate cell heating, posing a risk of thermal runaway, as evidenced by the exponential rise in temperature near critical points. Incorporating ambient temperature variation into the thermal model provides a more accurate representation of real-world operating conditions, especially within battery enclosures where thermal management is challenging.