Asia-Pacific Journal of Chemical Engineering最新文献

Addressing the issue of processing fine kaolinite and quartz particles in coal slime, this study utilized molecular simulation and Density Functional Theory (DFT) to investigate the chelate adsorption characteristics of sodium dodecyl sulfate (SDS) on kaolinite surfaces. As a major clay mineral component in coal slime, kaolinite reduces coal's calorific value but holds potential for industrial and agricultural applications. The research identified distinct interactions between SDS and the tetrahedral SiO layer and octahedral AlO layer of kaolinite, in contrast to quartz, which contains only the tetrahedral SiO layer. This difference is crucial for the effective separation of kaolinite from quartz. The study focused on analyzing SDS adsorption on the (001) and (00-1) planes of kaolinite. The findings revealed strong adsorption of SDS on kaolinite surfaces, especially on the (001) plane, evidenced by significant charge transfer indicating efficient chelation. This effect results from the interaction of SDS's electron-donating atoms (such as S and O) with the metal atoms on the surface of kaolinite. Adsorption strength was quantified through adsorption energy calculations, showing a stronger interaction on the (001) surface. Experimental validations, including single mineral flotation experiments and infrared spectroscopic analysis, further corroborated the simulation outcomes. These tests demonstrated improved flotation recovery of kaolinite in the presence of SDS and with reduced particle size. Infrared analysis revealed that SDS selectively and strongly adsorbs on kaolinite surfaces, as indicated by diminished hydroxyl group stretching vibrations in the FTIR spectrum and changes in absorption peaks related to inorganic vibrations and sulfonic acid groups. The study demonstrates that SDS can selectively and effectively adsorb onto kaolinite surfaces, particularly on the (001) plane, facilitating the efficient extraction of fine kaolinite from coal slime. This research holds significant potential for enhancing the utilization of resources from coal slime in the coal industry, offering both economic and environmental benefits.

The construction of high-efficiency self-supported ceramic photoelectrode based on ideal semiconductor materials is essential for achieving effective degradation of pollutants by photoelectrocatalysis (PEC) technology. Herein, a Ti₄O₇/h-BN composite ceramic photoelectrode with a unique microstructure was fabricated by a step-by-step calcination process and used in PEC water pollution remediation. The PEC activity of Ti₄O₇ ceramic photoelectrode could be enhanced by introducing hexagonal boron nitride (h-BN) nanoparticles on the surface. The most optimized Ti₄O₇/h-BN photoelectrode exhibited the decolorization rate of active brilliant blue KN-R at about 97.79% in 30 min. The PEC activities could remain stable during five degradation cycles. The excellent photoelectrocatalytic performance of Ti₄O₇/h-BN ceramic photoelectrode could be attributed to the low Tafel slope, low charge transfer resistance, large electrochemical active area, and excellent photo-generated carrier separation efficiency. A type-II heterojunction was formed between the Ti₄O₇ and h-BN, which caused more effective carrier separation and enhanced the generation of dominant active species •O²⁻ and h⁺. This work provided a mature synthesis strategy of Ti₄O₇/h-BN self-supported ceramic photoelectrodes with excellent practical application prospects to achieve superior PEC performance for water purification.

The lowered dispersibility of carboxylic acid polymers in the seawater system with high salt content results in reduced scale inhibition efficiency. To solve this problem, a series of carboxylic acid polymers containing ether groups were prepared by free radical polymerization using α-allyl glycerol ether (AG) and vinyl monomers containing different numbers of carboxylic acid groups (acrylic acid [AA], maleic acid [MA], itaconic acid [IA], and aconitic acid [ANA]) as raw materials, and their scale inhibition properties in artificial seawater were studied. The static test results demonstrate that IA-AG outperforms the other three polymers containing ether carboxylic acid in terms of scale inhibition performance, with CaCO₃ and CaSO₄ having scale inhibition rates of 95.16% and 98.73%, respectively. Furthermore, molecular dynamics (MD) simulation was employed to investigate the mechanism of scale inhibition by simulating the interaction between ether carboxylic acid polymers and the crystal surface. The results show that the order of binding energy between polymers and crystal faces is IA-AG > ANA-AG > MA-AG > AA-AG. The simulation results are in agreement with the experimental phenomena. The polymers can overcome their own deformation and adsorb on the crystal surfaces, thus inhibiting the growth of scale.

Mass transfer of bubbles is important in microalgae cultivation. In this study, aiming to improve the microalgae culturing efficiency, computational fluid dynamics (CFD) was adopted to study the influence of the aeration manners on mass transfer of bubbles within ascending columns in multi-column airlift photobioreactor (PBR) and the hydrodynamic conditions within the PBR under different aeration manners. In addition, the bubble generation time, the detachment diameter, and the average volumetric mass transfer coefficient of bubbles in ascending columns were analyzed. Furthermore, the experimental results were compared with the simulation results obtained from microalgae cultivation. The results showed that the whole aeration manner yields the lowest mixing strength and mass transfer efficiency of bubbles at an aeration rate of 0.2 vvm. Conversely, both the mixing strength of the liquid and mass transfer coefficient of bubbles were enhanced under the half and alternate aeration manners. However, the results demonstrated that the distribution of the flow field was not uniform under the half aeration manner and there were obvious high-speed and low-speed zones. In contrast, the flow field distribution in the PBR was more uniform under the alternate aeration manner, which was suitable for microalgae cultivation at high concentration. This study effectively enhanced the mixing strength and CO₂ transfer rate in the PBR.

The double-layer porous media burner is considered as an effective way to realize stable lean-burn. In order to quickly achieve a stable combustion state in a double-layer porous media burner, this work investigated the dynamic characteristics of methane/air premixed combustion in a bench-scale double-layer porous media burnspanning from ignition to stable combustion and ultimately flameout. The experimental results indicate that regulating the equivalence ratio and the inlet velocity enables the establishment of a stable flame front and the φ = 0.75 and the V_in = 0.20 m/s are the appropriate start-up conditions. The average propagation velocity of the combustion wave variation along the axial direction and ranged approximately from −0.022 to −0.078 mm/s. Moreover, the transition time to a stable combustion state is reduced by nearly 47.14% as the equivalence ratio increases from 0.60 to 0.70. During start-up stage, there are significant fluctuations in CO and NOx concentrations, but both emissions remain low during steady combustion state, with the maximum concentrations of 37.5 and 40.2 mg/m³, respectively. Furthermore, the porous media combustion exhibits a pronounced re-ignition capacity. At higher equivalence ratios, longer interruptions of premixed gas are allowed.

Dividing-wall column (DWC) provides tremendous advantages in terms of energy savings and capital costs for three-component and even multi-component separations. With increasing industrial application of three-component DWCs, DWCs for separation of four-component have received considerable research attention. The aim of this work is to investigate the design of the two-staggered wall region and gas–liquid two-phase flow behavior on the tray in a double-partition DWC (DPDWC). The Aspen Plus was applied to simulate the steady state to obtain the gas–liquid-phase flow rate in each region to serve as the basis for the tray design. In different task regions, the gas- and liquid-phase flow varied in some ways. The drag models have variability for the study of fluid flow, and the Tomiyama model is more appropriate. Moreover, high-velocity gradients and recirculating phenomenon can be discovered owing to the existence of multiple partitions in DPDWC.

Ethylene plays a crucial role as an intermediate component in the cracking and combustion processes of large molecular alkane and olefins. In this article, the laminar flame speed of ethylene–air mixtures was measured using the heat flux method. The mechanism of ethylene was simplified by utilizing the error propagation directed relationship graph (DRGEP) and sensitivity analysis (SA), and the Arrhenius pre-exponential factors for 20 selected reactions in the skeletal mechanism were optimized using the particle swarm optimization (PSO) algorithm. Finally, an ethylene optimization mechanism including 39 species and 85 reactions was obtained. The prediction results for flame speed, ignition delay time, and species concentration were compared with experimental data and other mechanisms, covering a wide range of temperatures (298–1725 K), pressures (1–22.8 atm), and equivalence ratios (0.5–2.0). The findings demonstrate that the optimization mechanism not only improves the prediction results of laminar flame speed in the rich combustion zone and low oxygen environment but also enhances the prediction accuracy of the ignition delay time at high pressure and in the lean combustion zone, as well as the prediction accuracy of C₂H₄ and H₂O radicals. In conclusion, the optimized mechanism exhibits higher accuracy and broader applicability.

In this work, snowflake-like α-CaSO₄·0.5H₂O (α-CSH) hierarchical architectures were successfully synthesized by a facile one-pot method in an ethylene glycol-water system using Na₂EDTA as a crystal morphology modifier. Characterization techniques including X-ray diffraction (XRD), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) confirmed the progressive morphological evolution of α-CSH from rods to snowflake-like structures ultimately to hexagonal plates with increased Na₂EDTA concentrations. The results revealed that Na₂EDTA concentration played a critical role in directing the crystallization and self-assembly of α-CSH, and a mechanism is proposed where Na₂EDTA modulated crystal orientation through preferential adsorption and regulated the driving forces between ion-mediated crystallization and particle-mediated assembly. This work puts forward a simple yet effective strategy for facilely regulating the morphology of α-CSH microstructures, which could potentially expand their applications across diverse fields such as composites, construction, biomedicine, and drug delivery.

The large-scale accumulation of industrial by-product gypsum has led to land embezzlement and serious environmental pollution. Meanwhile, as a predominantly used nitrogen fertilizer, urea shows a disadvantage of high solubility in soil. Therefore, it can hydrolyze into large amounts of ammonium salts so rapidly that cannot be absorbed efficiently by crops. The sustainable method of using industrial by-product gypsum to synthesize urea gypsum cocrystals is a promising way to solve above challenges. The synthesized urea gypsum shows low aqueous solubility and hygroscopicity, which can be used as sustained release fertilizer. In this review, the present status regarding urea gypsum is systematically reviewed, including its development history, preparation methods, impact of different raw materials, evaluation of products performance, and large-scale trials. This review aims to reveal the current situation, identify current gaps, and provide suggestions for future investigations concerning urea gypsum.

The dividing-wall column (DWC) stands as an energy-efficient distillation technology designed to efficiently separate ternary systems into their pure components within a single column. Despite its efficiency, integrating two towers into a DWC poses challenges in controllability. Published studies have focused on developing controllers for disturbance rejection but have not addressed the issue of servo control. Addressing this, our study proposes a servo controller problem and a methodical approach to strategically select controlled variables that undergo consecutive set point step changes, aiming to track the purity of key products obtained from the DWC. To achieve this goal, we developed a dynamic model specifically tailored to the DWC. Determining the design parameters involved employing a genetic algorithm optimization technique, minimizing the total annual cost. Subsequently, we implemented three servo parallel proportional-integral (PI) feedback controllers for three distinct product streams. The fine-tuning of their controller gain and reset time is carried out by minimizing the integrated square error while adhering to valve opening constraints. Our investigation revealed a limitation: the introduction of simultaneous step changes in all three controlled variables proved unfeasible with the three active PI controllers. As an alternative, our findings recommend prioritizing two variables: the lightest (distillate) and heaviest (bottom) key components, alongside the middle component (side stream) and either the lightest or heaviest key component. This research underscores the complexities of implementing step changes in multiple controlled variables within a DWC, offering insights into optimal control strategies for enhancing the efficiency of this innovative distillation technology.