Asia-Pacific Journal of Chemical Engineering最新文献

In this research work, bacterial cellulose was produced from the fermentation of coconut water and incubated for 4, 5, and 6 days. The bacterial cellulose membrane was utilized as immobilized silver nanoparticles (AgNPs). A green photocatalyst membrane was prepared by reducing silver ions in the bacterial cellulose matrix structure using local fruit extracts, tomatoes, Citrus hystrix fruit, and mangosteen peel as a reducing agent. The composite was dried in the oven to obtain a more durable fixed structure. The properties of produced bacterial cellulose were determined by measuring the thickness, water retention capacity (WRC), cellulose content, and swelling. The functional group and crystallinity index of bacterial cellulose were observed by FTIR and XRD instrument analysis. The SEM EDX analysis confirms that the silver ions were successfully reduced in the BC matrix, and the UV–Vis spectrum showed that the composite membrane has the ability to degrade the methylene blue solution under sunlight irradiation. The maximum degradation efficiency of the composite membrane against 5 ppm methylene blue solution was achieved by the composite membrane reduced by tomatoes, with a value of 93%. This result proved that the composite membrane produced in this research has excellent capabilities as a green photocatalyst for degrading wastewater containing dye pollutants.

The effects of coal gangue (CG) on the ash initial deformation temperature (IDT) and CO₂ gasification characteristic of biomass (chestnut shell [CS] and soybean straw [SS]) were investigated by ash fusion tester and thermogravimetric analyzer, respectively. The IDTs of CS and SS ashes were low because of the presence of abundant low melting point (MP) airchildite (K₂Ca(CO₃)₂) and arcanite (K₂SO₄), and they were efficiently improved by the CG additions of 2%–10% mass ratios. The increases in the IDTs of CS and SS ashes were resulted from the conversions of fairchildite and arcanite into high MP K-Al silicates (kalsilite [KAlSiO₄], leucite [KAlSi₂O₆], etc.). The gasification reactivities of CS/CG mixtures stayed below that of CS, and they decreased with increasing CG mass ratios (4%–10%) and increased with increasing temperatures (900–1000°C). At 900°C, CG addition caused a decrease in the gasification reactivity of SS. When the temperature reached 950°C, the CG addition of 4% mass ratio increased the gasification reactivity of SS instead. The synergistic effect between biomass and CG during cogasification was more significant at low CG mass ratio and high temperature, and the synergistic effect between SS and CG was more intense than that between CS and CG.

Deep eutectic solvents (DESs) are becoming increasingly promising as environmentally friendly solvents, and accurate prediction of their density and viscosity is crucial for their successful industrial application. However, existing density and viscosity prediction models primarily rely on temperature variations and often overlook changes in the molar ratio of hydrogen bond acceptors (HBA) to hydrogen bond donors (HBD) in DESs, limiting their practicality. Therefore, in this study, several binary and ternary DESs were synthesized using choline chloride (ChCl) as the hydrogen bond donor. The densities and viscosities of these DESs were measured, and prediction models for the density and viscosity of DESs based on temperature and molar ratio were developed. These models were used to forecast the density and viscosity of DESs at different temperatures and molar ratios. The model parameters are calibrated using experimental data from this research. Finally, the model is utilized to predict the density and viscosity of DESs mentioned in this paper, as well as DESs with varying HBAs and HBDs. The results demonstrate that the discrepancy between the literature value, experimental value, and calculated value is less than 6%, confirming the universal applicability and reliability of the prediction model proposed in this study.

Understanding the collision between kerosene droplets and coal particles in the bubble trailing vortex region is crucial for enhancing slurry conditioning. We found the area of the bubble trailing vortex region increased as the bubble size increased via the Fluent 6.3.26 software. A kerosene droplet velocity range of 0.074–0.106 m/s and a coal particle velocity range of 0.062–0.104 m/s were obtained if a bubble had a diameter of 0.3 mm. We employed a high-speed motion acquisition system and observed the collision process, which was divided into two stages: Compression and Rebound. The critical motion distance increased as the kerosene droplet size increased, and sufficient kerosene droplet motion distance and enough kinetic energy normally resulted in a rebound phenomenon. The attenuation energy was almost positively linear to the initial energy, and the energy attenuation coefficient of the collision process was fitted to 0.626. Our results can provide valuable insight into mineral separation.

With the development and utilization of high-sulfur coal, generating ammonium bisulfate (ABS) and ammonium sulfate (AS) during the coal combustion process has garnered increasing attention. This study examined the formation of ABS and AS under varying temperatures and different initial reactant ratios of SO₃ and NH₃ by establishing a self-constructed experimental setup. Based on the experimental data, the equilibrium constant change diagram for the ternary reactions leading to ABS and AS formation was derived. The initial temperatures for forming gaseous ABS and AS were estimated to be approximately 416.33°C and 393.56°C, respectively. Consequently, this study fills the data gap of the equilibrium constant of gaseous ABS formed at high temperatures and furnishes the selective catalytic reduction (SCR) system with quantifiable and notably expedient means of technical analysis.

A series of Fe₆Mn₁Cu_x adsorbents for mercury removal were prepared by using co-precipitation and impregnation methods. The performance of mercury adsorption and anti-SO₂ characteristic was studied in a fixed-bed experimental system. The effect of Cu doping amount, reaction temperature, and flue gas components on mercury removal was investigated. The mercury species on the spent adsorbent was analyzed through Hg-TPD test. The physical–chemical features were characterized by using the N₂ adsorption/desorption, VSM, XPS, and XRD. It was found that the Fe₆Mn₁Cu_0.4 exhibited a high performance of mercury adsorption and well magnetic property and good sulfur resistance. Under high concentration of SO₂, the average adsorption efficiency of Fe₆Mn₁Cu_0.4 adsorbent achieved 99%. Cu modification optimized the pore structure and improved the mercury removal performance as well as SO₂ resistance. The XPS analysis indicated that Mn⁴⁺ was the main form that played an important role in oxidizing Hg⁰, as a result of decrement of Mn⁴⁺ after mercury adsorption. Mercury adsorbed on the spent adsorbent was HgO and HgSO₄.

Alkynyl alcohol derivatives (N-14) were synthesized by 2-chloromethyl pyridine, propargyl alcohol and bromotetradecane and the structure was confirmed by ¹H NMR, ¹³C NMR, MS and FTIR. The corrosion inhibition performance was evaluated by weight loss, Tafel polarization, EIS measurements and DFT quantum calculations. The results proved that N-14 effectively inhibited the acid corrosion of N80 steel. The corrosion inhibition of N-14 increased with its concentration and decreased with increasing temperature. A maximum of 99.56% inhibition efficiency was achieved using 5 × 10⁻⁵ mol/l of N-14 at 60°C. Thermodynamic parameters showed that the adsorption of N-14 on N80 steel is spontaneous and exothermic, conforming to Langmuir's adsorption. Electrochemical results showed that N-14 behaved as a mixed-type inhibitor. In addition, corrosion products produced on N80 steel surface were researched by SEM, XRD, UV and contact angle. At the same time, the corrosion inhibition mechanism was discussed.

The study presents the development and characterization of rubberized fibrillated polystyrene composites using recycled rubber tires and pawpaw fibres. The composites were prepared by varying the proportions of rubber and fibre. FTIR, SEM, EDX and hardness testing were used to characterize the composites. FTIR spectroscopy revealed distinct peaks, including hydroxyl and amine, but with a notable absence of the O-H group in nearly all composites, affirming their durability and potential suitability for applications in moist environments. SEM results showed that the introduction of rubber tires did not significantly alter the smooth and fine-grained nature of the polystyrene resin, whereas the inclusion of pawpaw fibre resulted in an irregular and coarse surface. Mechanical testing demonstrated that the hardness of the composites was dependent on the composition, with rubber-rich composites being more flexible and pawpaw-fibre-rich composites exhibiting greater rigidity.

Various engineering applications commonly involve the flow of nanofluids over a porous 45° inclined square cylinder. Therefore, the current study is to assess the impact of the Darcy parameter (Da), nanoparticle volume fraction (ϕ), and Reynolds number (Re) on the momentum transport characteristics over the 45° inclined porous square cylinder. The governing equations were solved numerically using the Darcy–Brinkman–Forchheimer model for different values of Da ($�{10}^{�-�6�}�\le �\mathrm{Da}�\le �{10}^{�-�2�}$), nanoparticle volume fraction ϕ ($�0.01�\le �\varphi �\le �0.05$), and Reynolds number Re ($�1�\le �\mathrm{Re}�\le �40$). The results for each parameter were visualized using streamline plots, velocity profiles within the porous cylinder, and vorticity contours. Complex flow behaviors were observed between Da = 10⁻³–10⁻², flow separation detached and disappeared at the cylinder's downstream side at critical Darcy number. Drag and pressure coefficents are used to represent the global and local parameter of the flow fields. The pressure coefficient on the surface of the cylinder showed an inverse relationship with the nanoparticles volume fraction and Darcy number. The strength of the drag coefficient decreased with the addition of nanoparticles to the base fluid, with a decreasing trend observed for Da = 10⁻⁴–10⁻² and no change observed for Da = 10⁻⁶–10⁻⁴. At last, the comparative analysis has been conducted between a porous square cylinder at 0° inclined and another 45° inclined.

Pyrometallurgical method of iron recovery from red mud (RM) has advantages of simple procedures, high recovery efficiency and significant waste minimization. The fluidization reduction process using CO as reductant addresses the issues of high energy consumption and long reaction time of pyrometallurgical method. In order to optimize the operational conditions of the fluidization reduction process, it is necessary to study the reaction characteristics of RM and CO under fluidization condition. In response to the problems of the current kinetic study including the unsatisfied fluidization condition and possible errors introduced by the estimation method, we carried out improvements in both experiment and data processing. In the experiment aspect, thermo-gravimetric analyzer (TGA) test rig with large sample capacity and gas flow was established, and approximate fluidization condition was achieved by intensifying diffusion by increasing the gas flow rate and decreasing the sample mass. In the data processing aspect, we developed a program with data cleaning and kinetic function fitting capabilities, and the goodness of fit was evaluated by Akaike information criterion (AIC). The results indicated that within the temperature range of 500–600°C and CO concentrations of 5%–15%, the reaction between RM and CO can be divided into two steps based on the criterion of complete formation of Fe₃O₄. The first step reaction has a relatively fast reaction rate, conforming to the F1 kinetic function with rate equation given as $�k�=�3�.�46�\exp �(�-�4�.�48�\times �1�{�0�}^{�3�}�/�T�)�{�c�}_{�C�O�}$. The second step reaction displays a more complex pattern and the fitted rate equation is $�k�=�5�.�57�\times �1�{�0�}^{�-�2�}�\exp �(�-�4�.�16�$