Canadian Journal of Chemical Engineering最新文献

This investigation focuses on the dynamic behaviour of the steady, pressure-driven flow of a two-dimensional viscous incompressible fluid around circular cylinders of equal diameter within a rectangular permeable microchannel featuring wall roughness. The wall roughness is modelled by implementing Navier's slip condition on the horizontal channel walls with a phase difference, examining both small and large-patterned wall roughness scenarios. The flow, characterized by a low Reynolds number, is subjected to an inclined magnetic field, while the induced magnetic field effects are neglected under a low magnetic Reynolds number assumption. The Brinkman equations describing the flow are solved using the boundary element method (BEM) based on stream function and vorticity variables. The results indicate that increasing Darcy numbers enhances the permeability of the porous medium, reducing flow resistance, particularly away from the channel walls. The Lorentz force maximizes drag when perpendicular to the flow and becomes less effective as the magnetic field inclination increases. Shear stress is minimized at Navier's slip and no-slip conditions interface. This investigation supports advancements in targeted drug delivery in microfluidic applications, optimization of lab-on-chip devices for diagnostics, and improvement of fluid dynamics in heat exchangers and filtration systems.

The performance of an axial spiral stirrer in mixing two aqueous and organic phases in a tank at different test conditions has been studied, and its effect on copper ion extraction was determined. The influence of speed, O/A, pH, and tank baffle parameters were investigated. Experiments were also done without a baffle, requiring a smaller tank diameter to study the effect of radial tip clearance without baffles. Mass transfer has been assessed by measuring the overall mass transfer coefficient and Sherwood number. Examination of the samples collected from nine locations on the stirring tank wall with the larger baffled tube diameter showed that apart from the speed of the stirrer, the extraction of Cu ions was influenced by the presence of baffle, liquid O/A ratio, and pH in that order. Cu ion extraction at optimal conditions (600 rpm, O/A = 1.2, pH = 2.5, and with baffle) at the end of the stirring time (180 s) was already at 99.5%. Moreover, the stirred flow axial concentration was uniform. The results of tests with a smaller diameter tank (i.e., without baffle) showed that the radial distance between this stirrer and the tank wall without the baffle after 360 s had only a 6.5% negative impact on Cu ion extraction effectiveness with the same optimal test conditions (600 rpm, O/A = 1.2, pH = 2.5), and an axially non-uniform fluid concentration was observed. Also, the large value of Sherwood numbers acquired from all the experiments (in the 300 s) gave insight into the improved performance of this stirrer design compared to pure diffusion.

HZSM-5 zeolites were treated by alkaline and alkaline–acid composite modification via the hydrothermal method. A comprehensive series of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂ adsorption–desorption, temperature-programmed desorption of ammonia (NH₃-TPD), and pyridine adsorption infrared spectroscopy (Py-IR), were employed to investigate the physicochemical properties of the ZSM-5 zeolites before and after modification. The results demonstrated that the relative crystallinity of the modified zeolites remained nearly intact, with the MFI structure being well-preserved. Nevertheless, the total acid content of both modified samples decreased, accompanied by an increase in specific surface area and pore size. Notably, the zeolites treated with alkaline–acid composite modification showed a slight elevation in the total L-acid content. When applied to the reaction of coupling methanol with raffinate oil for the production of light olefins, compared with the unmodified ZSM-5 zeolite, the modified ZSM-5 zeolites showed a significant increase in the selectivity and yield of triene. In particular, the ZSM-5 zeolite A2 modified by the alkali–acid composite method exhibited remarkable enhancements in catalytic activity and stability. Its methanol conversion rate exceeded 99%, and when the selectivity for triene reached 60.26%, the yield reached a high value of 36.8%.

Methylparaben, commonly found as an emerging contaminant in personal care products and pharmaceuticals, have raised concerns due to their potential endocrine-disrupting effects on humans and male fish. Nano-filtration presents a viable alternative for mitigating this contamination. In this paper, the first part explores advances in various methods, each of which facilitates the separation of paraben from aqueous media. In the later experimental segment, the flat sheet membrane module is used for nano-filtration, for different operating parameters. The two NF300 & NF100 membranes are employed to see the efficiency of removal of nethylparaben from synthetic wastewater. The removal efficiency of methylparaben by NF300 membrane is 32.64%, while the removal efficiency by NF100 membrane is 70.46%. The efficiency of the membrane increases with the increase in pressure and decrease in the concentration. The outcome shows nano-filtration is a promising technology for addressing the emerging contaminant methylparaben in waste water.

This study aimed to determine the optimum conditions for the lipolysis of tengkawang fat using lipase derived from frangipani resin to produce free fatty acids, which, particularly stearic acid, serve as key intermediates in various industrial applications. A 2^(4–1) fractional factorial design was used to screen the effects of pH, temperature, enzyme concentration, and buffer-to-fat ratio on the degree of lipolysis. The 5-h reaction yielded a reaction mass of 43.35% of free fatty acids. ANOVA results revealed that pH, enzyme concentration, and their interaction were significant, with curvature present at the centre point. Optimization was then conducted using response surface methodology (RSM) with a face-centred central composite design (FCCCD). The highest degree of lipolysis achieved was 89.54% under the conditions of pH 7, temperature 27°C, enzyme concentration 10%, and a buffer-to-fat ratio of 2:1. Time profile observations showed that the lipolysis reaction proceeded slowly, reaching 89.53% at the end of 24 h.

Silica nanoparticles (SiNPs) are promising drug delivery nanocarriers due to their tunable size, porous structure, and surface properties. This study compares two synthesis methods: (i) a low-temperature aqueous sol–gel process yielding SiNPs of 500–700 nm, and (ii) a water-in-oil (W/O) microemulsion using either CTAB or TX-100 surfactants. Surfactant selection significantly affected nanoparticle size, stability, and dispersity. Characterization by dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), solid-state nuclear magnetic resonance spectroscopy (ssNMR), X-ray photoelectron spectroscopy (XPS), and photoluminescence analysis (PL) confirmed successful synthesis. The TX-100-mediated microemulsion method proved particularly effective in achieving highly stable, reproducible, and monodisperse SiNPs, with a size limit of approximately 100 nm, making them ideal candidates for drug encapsulation. Procaine (PRC) incorporation demonstrated the role of reverse micelle dynamics and surfactant-stabilized interfaces in enhancing encapsulation efficiency. This work highlights the critical role of surfactant and medium selection in SiNPs synthesis, demonstrating their impact on nanoparticle stability, dispersity, and drug loading efficiency. The TX-100-mediated microemulsion technique emerges as a superior approach for producing stable, monodisperse SiNPs, advancing the design of nanocarriers for PRC drug delivery applications.

The phenomena of bubble formation from the venturi pipe microbubble generator were investigated. The air hole sizes were varied at 1, 0.5, and 0.3 mm while the volumetric flow rates were set at 4, 5, 6, 7, and 8 LPM. Insertion of a guitar string with a diameter of 0.2 mm into the 0.5 mm air hole size was also performed to examine its effect. The simulation of the bubble shrinkage process in water (sizes of 25, 50, 75, and 100 μm) was held with and without saturated nitrogen at 0.25, 0.5, 0.75, 0.875, and 1 atm. The experiment shows that average bubble sizes for air hole sizes of 1, 0.5, and 0.3 mm are 1.37, 1.40, and 1.09 mm, respectively. The flow rate alteration significantly affects the bubble sizes for air hole sizes of 0.5 and 0.3 mm but is not meaningful for 1 mm. In addition, the guitar string insertion also produces spherical bubbles with a size of 1.33 mm for deep depth location. Moreover, simulation results prove that smaller bubble sizes lead to prolonged shrinkage time and a greater mass transfer coefficient in the liquid phase with and without saturated nitrogen.

This study applies neural ordinary differential equations (neural ODEs) to model hydrocracking kinetics, a key process for converting heavy hydrocarbons into lighter products like gasoline and diesel. Neural ODEs provide a data-driven approach, learning reaction dynamics directly from data without requiring explicit assumptions on kinetics, addressing limitations in traditional methods. Two neural ODE models were trained on synthetic hydrocracking data representing different kinetic assumptions: one based on a 2.5-order reaction scheme (Model A) and the other on a first-order scheme (Model B), across varying temperatures and feedstocks. The models demonstrated high predictive accuracy when predicting within the range of training data, with RMSE values remaining below 0.5 wt.% under most conditions. However, performance declined during high-temperature extrapolation scenarios, particularly for the higher-order model, revealing challenges in capturing nonlinear dynamics at extreme conditions. This work also enhanced the interpretability of neural ODEs by analyzing gradients within the model, which validated alignment with known kinetic principles, uncovering critical information about reaction pathways and temperature sensitivities. This analysis demonstrated the models' ability to capture temperature-dependent behaviour and rate stabilization, as illustrated through heat maps, which further emphasized the potential of neural ODEs for both predictive accuracy and interpretative insights in hydrocracking modelling. Additionally, the extracted gradients present an exciting avenue for future advancements, such as leveraging symbolic regression techniques to uncover governing equations.

Ethyl cellulose (EC) is one of the important coating materials for the short-term protection of precious metals and jewellery. In this study, graphene oxide (GO) was introduced in EC films, and electrochemical impedance spectroscopy (EIS) was utilized to probe the ion permeation through the films. EIS results demonstrate the film resistance increased with the GO content from 0 to 1 wt.%, and decreased with the GO content from 1 to 4 wt.%. It indicates that the ion penetration first becomes difficult and then easier with the increase in GO content. SEM results reveal that the pore sizes of the doped EC composite films first decrease and then increase with the increase of GO content. Additionally, water contact angle results indicate that introducing GO enhanced the surface hydrophilicity of the EC composite film. The tensile test shows that the EC/GO composite film achieves the best mechanic property at the GO content of 1 wt.%. These findings indicate that the pore structure of EC could be adjust by GO platelet, which could be an easy method to modify the ion barrier through EC film.