Asia-Pacific Journal of Chemical Engineering最新文献

In this study, marble waste (MARWAS) beneficiation was done using thermal, physical, and chemical means. The MARWAS samples collected from dumping yards of Kishangarh and Revdar districts of Rajasthan (India) and Ambaji district of Gujarat (India) were characterized by chemical composition analysis, scanning electron microscopy with energy-dispersive spectroscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). These were then subjected to different beneficiation schemes: (1) calcination followed by slaking and clarification, (2) cationic reverse floatation, and (3) acidulation followed by magnetic separation. These aim to enhance the calcite content by removing siliceous and ferrous impurities. The percentage removal of impurities (PRIs) of these schemes was calculated using chemical composition analysis of purified products. The acid dissolution method (PRI = 93.97%) was more efficient for eliminating siliceous than the reverse floatation method (PRI = 68–73%), while the magnetic separation (PRI = 99.32%) completely removed the ferrous impurities. Although the PRI is just about 45% in the calcination method, it is useful for decomposing the material to eliminate the impurities strongly entangled between the calcite matrix. Purified products (CaO, Ca (OH)₂, and CaCl₂) obtained by these beneficiation schemes can be used to synthesize high-grade CaCO₃ powder to serve as a feed supplement in poultry, filler in papermaking, and in toothpaste, etc.

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.

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.

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.

Due to its small size, microchannel heat exchangers are widely used in fine engineering fields such as electronic equipment. In this paper, the boiling heat transfer characteristics of refrigerants and nanofluids in microchannels are studied by applying electric fields, magnetic fields, and electromagnetic synergistic fields. Compared with deionized water, using R141b refrigerant with a boiling point of only 32.1°C as the base liquid can better achieve two-phase flow boiling heat transfer. The results show that the addition of magnetic nanofluids can significantly improve the heat transfer efficiency, and the heat transfer efficiency is greatly improved by applying electric and magnetic fields at the same time. Compared with pure refrigerant, the application of electric field and nanofluid can increase the average heat transfer effect by 17% and 9%, respectively, within the full load range, while applying electric field and magnetic excitation, respectively, on the basis of nanofluid can bring about the improvement effects of 24% and 29%. After applying electromagnetic synergistic excitation to the nanofluid, the average heat transfer enhancement effect within the full load range reaches 36%.