Asia-Pacific Journal of Chemical Engineering最新文献

The presence of pharmaceutical pollutants in the environment has become a growing concern due to their persistence and toxic nature. In response to this issue, semiconductor photocatalyst materials have emerged as promising candidates for environmental pollutant removal, particularly under solar light irradiation. In this study, we developed a novel zeolite/Fe₃O₄/CuS/CuWO₄ heterojunction nanocomposite through a simple and facile method. The fabrication process involved a multistep approach wherein Fe₃O₄, CuS, and CuWO₄ were incorporated onto the surface of pure zeolite nanoparticles. X-ray diffraction, scanning electron microscope, transmission electron microscope, ultraviolet–visible diffuse reflectance spectroscopy, Fourier transform infrared, photoluminescence, and vibrating sample magnetometry were analyzed. The results demonstrated that the zeolite/Fe₃O₄/CuS/CuWO₄ heterojunction nanocomposite exhibited a synergistic integration of excellent properties, indicative of the successful construction of a heterostructure within the nanocomposite. Furthermore, the photocatalytic efficiency of the nanocomposite was evaluated for the degradation of the pharmaceutical pollutant fluoroquinolone levofloxacin (LEVO), and it outperformed individual photocatalysts. Notably, the zeolite/Fe₃O_4/CuS/CuWO₄ nanocomposite achieved an impressive degradation rate of approximately 82.67% of LEVO after 120 min of exposure. Importantly, the synthesized nanocomposite demonstrated excellent reusability, with a photodegradation efficiency of 60.45% after the fifth cycle of LEVO degradation, as there was no significant loss in photocatalytic activity over repeated cycles. Furthermore the highest total organic carbon removal efficiency estimated is 57.43% for heterojunction nanocomposite. These findings highlight the potential of the zeolite/Fe₃O₄/CuS/CuWO₄ heterojunction nanocomposite as an effective, eco-friendly photocatalyst for pharmaceutical pollutant removal from the environment.

Thermal systems for solar air heating have been widely used in both industrial and residential contexts, and are essential for converting and recovering solar energy. Thermal performance in solar air heaters (SAHs) can be improved through the repetitive application of artificial roughness to the surfaces. This research work includes a numerical evaluation of SAH performance with artificial rough surfaces made up of combined transverse trapezoidal ribs and chamfered grooves. The ANSYS Fluent software version 2023 R1 was used to simulate SAH with varying relative roughness pitch ($�P�/�e�=�7.14�-�35.71$), relative roughness heights ($�e�/�D_h�=�.021�-�.042$), and Reynolds number ($�\mathrm{Re}�=�6000�-�18��000$). The RNG $�k�-�ϵ$ model was chosen to forecast an enhancement in Nusselt number ($�\mathrm{Nu}$), friction factor ($�f$), and thermohydraulic performance factor (TPF) for the proposed roughness. Out of multiple roughness parameters analyzed, it was determined that the compound turbulator with $�P�/�e�=�10.71$ and $�e�/�D_h�=�.042$, were the most effective. The TPF for this scenario was determined to be 2.12 at $�\mathrm{Re}�=�6000$. Finally, a numerical based empirical correlations for $�\mathrm{Nu}$ and $�f$ in terms of Re, $�P�/�e$, and $�e�/�D_h$ were developed.

The jet impingement flash technology represents a paramount research subject in the domain of heat and mass transfer. To augment its commercial potential, the conjunction of annular multi-aperture jet impingement with negative pressure flash evaporation is introduced in this study. The employment of an annular nozzle array is integral to the enhancement of the heat and mass transfer efficiency between the phases. The Realizable k-ε model is used in this study. The negative pressure flash vaporization model was also developed by introducing a mass source term and an energy source term based on the Mixture model. The flow characteristics are characterized using numerical simulation. Additionally, the λ₂ vortex identification criterion is investigated the vortex structure. The simulation results exhibit good agreement with experimental findings, demonstrating that a higher initial vacuum leads to a stronger flashing effect and a more chaotic movement of the flow group within the flow field. Thus, this study provides a reference method for the structural design and optimization of annular symmetric jet impingement negative pressure deammonia chemical equipment for engineering applications.

The performance of Cu/ZnO/Al₂O₃ (CZA) catalysts promoted by addition of CeO₂, MnO₂ or ZrO₂ in direct methanol production from unconventional syngas was experimentally investigated. The unconventional syngas used in this study contain 25% H₂, 25% CO, 20% CH₄, 20% CO₂ and 10% N₂, representing biomass-derived syngas cultivated from an industrial wood chips pyrolysis plant. The catalysts were synthesised using co-precipitation technique and tested for methanol synthesis in a fixed-bed reactor. The activity test of the catalysts showed that the addition of CeO₂ or ZrO₂ to the CZA catalyst improved the methanol yield, albeit with lower selectivity, whereas adding MnO₂ enhanced methanol selectivity but decreased the methanol yield. ZrO₂-promoted catalyst showed the best-improved activity and stability. The calcined and spent catalysts were characterised using X-ray diffraction (XRD), N₂ physisorption, N₂O chemisorption, hydrogen temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The characterisation results indicate that the catalytic activity is dependent on Cu dispersion, Cu-active surface area, the catalyst reducibility, Brunauer–Emmett–Teller (BET) surface area and the Cu⁰/Cu⁺ ratio. In contrast, catalyst stability was related to the proportion of Cu⁺ among all surface Cu species.

In this work, we have specially carried out the catalytic cracking experiments of heavy distillate oil in the high temperature range of 500~700°C. The composition of dry gas generated in the catalytic cracking process was analyzed, with emphasis on the variation of yield of C₁ and C₂ products. Two cracking mechanism ratios (CMRs) were redefined by replacing the (C₁ + C₂) products in the traditional definition of CMR with CH₄, and the feasibility of using them to characterize the thermal cracking reaction in the catalytic cracking process in the high temperature range was investigated. The results showed that CH₄ was more sensitive to temperature than (C₁ + C₂) and it was feasible and more accurate to use CH₄ instead of (C₁ + C₂) corrected R3 to characterize the thermal cracking reaction in the catalytic cracking process in the high temperature range. In addition, it was found that the corrected R3 had the effect of distinguishing and identifying catalysts.

Adrenaline (AD) is important in information transmission through the human central nervous system. Considering the significant biochemical functions of AD, the development of electrochemical sensors capable of detecting AD levels in living organisms has attracted considerable interest. In this study, AD was detected using electrochemical sensors developed based on Au nanoparticles/ionic liquids/N- and P-co-doped carbon nanotubes-modified carbon cloth (AuNPs/ILs/N,P-MWCNTs/CC) electrodes. AuNPs/ILs/N,P-MWCNTs/CC composites were prepared on carbon cloth (CC) substrates using ionic liquids (ILs), N- and P-co-doped multi-walled carbon nanotubes (N,P-MWCNTs), and Au nanoparticles (AuNPs) as modified materials. The effects of pH and scanning speed were optimized and tested on the prepared composites. The results of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) experiments showed that the modified ILs, N,P-MWCNTs, and AuNPs effectively improved the oxidation performance of AD. In addition, the linear range obtained from the DPV scans of the AuNPs/ILs/N,P-MWCNTs/CC composite material was 30–505 μmol/L, with a detection limit of 0.31 μmol/L. The fabricated sensors have good sensitivity (6.9 μA·mM⁻¹·cm⁻²) for AD of 30–505 μM. Therefore, the electrochemical sensing method based on the AuNPs/ILs/N,P-MWCNTs/CC composite material is a promising and reliable AD detection technology that also exhibits good selectivity in the presence of interfering substances such as folic acid and ibuprofen. In practical applications, this material can help realize real-time AD detection to determine whether athletes use doping and other illegal drugs before competitions and to perform synchronous detection.

Steam Rankine cycle (SRC), which is mainly utilised in power generation sector, faces external irreversibility in its daily operation causing inefficiency in the system. To address this issue, reheat Rankine cycle (RHRC) and regenerative Rankine cycle (RRC) have been widely studied and implemented in power plants to improve thermal efficiency and reduce external irreversibility of Rankine cycle. This study investigates the implementation of different RRC configurations in a combined heat and power plant, including RRC with modified thermal deaerator, RRC with open feed water heater (OFWH) and closed feed water heater (CFWH). A base case simulation model was first constructed using commercial simulation software Aspen HYSYS for the basic SRC system based on actual plant data. Various scenarios were then evaluated for their profitability and sustainability through techno-economic analysis (TEA) and carbon footprint analysis (CFA). From both analyses, the scenario of RRC with CFWH showed the greatest long-term potential, generating the highest annual profit of $ 771 691 and carbon footprint reduction of 14.63%, while RRC with modified thermal deaerator showed the greatest potential in the short run with the highest return of investment (ROI) of 201.51% and shortest payback period (PBP) of 0.50 year.

In the natural environment, plastics and microplastics (MPs) are difficult to break down due to their hydrophobicity, the presence of persistent covalent bonds, and their functional groups' resistance to attack. The destiny of both organic and inorganic pollutants at contaminated areas can be influenced by MPs ability to absorb them. Because of their enormous surface to volume ratio and chemical surface characteristics, MPs are able to absorb dangerous substances from their surroundings. Accordingly, the study's main objectives were to provide a concise review of characterization techniques of MP biodegradation techniques, including the nano-enabled methods, and the gaps in current research were outlined. This review paper summarizes the degradation mechanism and efficiency of MPs in different circumstances. For the purpose of eliminating plastic pollution, this work will help for the further studies.

Aviation lubricating oil, as the “blood of machine operation”, plays an important role in the lubrication, cooling, cleaning, sealing, rust prevention, and other aspects of aero-engines, thereby ensuring the safe and stable long-term endurance of aero-engines under high-speed and high-temperature conditions. The thermal oxidation of aviation lubricating oil leading to decay is the most important factor causing lubricating oil failure, which will seriously affect the performance of aero-engines and endanger flight safety. Here, we comprehensively summarize the oxidation mechanism of aviation lubricating oil, factors affecting thermal oxidation of aviation lubricating oil, evaluation methods for thermal oxidation of aviation lubricating oil, and antioxidants that inhibit thermal oxidation of aviation lubricating oil. We hope that this review can enhance readers' understanding of the thermal oxidation of aviation lubricating oil, stimulate broader interest, and promote more exciting development in this promising field.

In order to study the crystallization blockage law and crystallization mechanism of dolomite tunnel drainage system, based on the indoor model test, the simulated crystal blockage and growth process were simulated. The phase composition and microstructure of the crystal were analyzed by energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Combined with the pipeline crystal weighing, the crystal growth law and the internal cause of pipeline blockage were analyzed. The results show that the pipeline crystallization mechanism is divided into the first mechanism, the second mechanism, and the third mechanism. The crystallization blockage of the longitudinal and horizontal pipes are more serious, while the crystallization blockage of the ring pipes are less harmful. The crystallization is positively correlated with ion concentration, crystalline ions having a great influence on the blockage of pipeline crystallization, while noncrystalline ions having little influence. The crystal growth law is fast first and then slow, the crystallization affected by the coupling concentration of Cl⁻-K⁺-Na ⁺ ions, and positively correlated with the coupling concentration of CO₃²⁻-SO₄²⁻-Ca²⁺-Mg²⁺-Al³⁺ ions. Compared with the longitudinal pipes and the ring pipes, the horizontal pipes have more crystallization and higher degree of crystallization blockage per meter, while the crystallization degree of the longitudinal pipes are between the horizontal pipes and the ring pipes.