ACS Engineering Au最新文献

In this paper, we demonstrate that life cycle assessment (LCA) is a valuable tool for evaluating the trade-offs between critical mineral acquisition and its resulting environmental impacts, but the applications of LCA to critical mineral mining are inconsistent and limited. These inconsistencies inhibit effective comparison of mines' effects and decision-making in support of environmentally responsible mineral supply chains. To illustrate these limitations, we analyzed how 74 peer-reviewed and gray literature critical mineral mining LCAs applied the four phases of LCA. To further assess how these LCAs account for environmental impacts, we created a data set of critical mining impacts reported in the EJ Atlas. Based on this thorough assessment, we propose a series of guidelines for each LCA phase for application to critical mineral mining. These recommendations provide an opportunity to standardize critical mineral mining LCAs and enable better comparison to inform decision-making and mining policy development.

Personal care products are often dynamically formulated in situ. Variations in the chemistry of the base components (e.g., their polydispersities or ionic contents) require extensive off-line rheological analysis to ensure the products meet benchmarks for performance and thus consumer satisfaction. An in-line alternative for rheological quality control and monitoring thus has the potential to improve efficiency on industrial pipelines. Therefore, we demonstrate optical coherence tomography velocimetry (OCT-V) for the in-line processing of a shampoo based on SLES and CAPB with varying concentrations of salt. OCT-V is a noninvasive quasi-elastic light scattering technique, capable of spatially resolved velocity measurements with an axial depth resolution of 9 μm and a penetration depth of 1.5 mm into the samples. Our in-line apparatus uses infrared light (the wavelength is 1315 nm) and has been optimized for live manufacturing with a 200 L test rig at the Unilever R&D lab. The addition of salt to the shampoo is used for in situ formulation to increase the viscosity, inducing the spherical-to-wormlike micelle transition. To create in-line rheological benchmarks, we measured time averaged velocity profiles and transient velocity fluctuations in the shampoo formulations at imposed flow rates of Q = 500 and 1000 L/h. For a shampoo formulation with 1.1% NaCl salt, fits of the Hagen-Poiseuille equation to velocity profile data give flow rates that are in close agreement with the imposed values, Q _HP = 502 ± 2 L/h and 944 ± 4 L/h, corresponding to a 0.4% and 5.6% error, respectively. Combined with measurement of the longitudinal pressure drop, this could be used to calculate constitutive properties, such as the viscosity. The standard deviation of the distribution of transient velocity fluctuations is a decreasing function of salt concentration due to the increasing viscosity. If calibrated to the desired end product, the velocity fluctuations could also be used as a reproducible indicator of product quality on industrial pipelines.

Atmospheric water harvesting (AWH) is a method to obtain clean water in remote or underdeveloped regions including, but not limited to, those with an arid or desert climate. For passive (i.e., relying on ambient cooling and, for heating, natural sunlightas opposed to an external power source), adsorbent-based AWH, an adsorbent bed is employed to capture water from cold, humid air at nighttime, while during the daytime the bed is then exposed to natural sunlight to heat it and desorb the water for collection. Metal-organic frameworks (MOFs) are tunable, nanoporous materials with suitable water adsorption properties for comprising this adsorbent bed. The water delivery by the MOF adsorbent bed in a passive AWH device depends on (1) the nighttime, capture conditions (temperature and humidity) and daytime, release conditions (temperature, humidity, and solar flux) and (2) the structure(s) of the MOF(s) comprising the bed, which dictate MOF-water interactions. Notably, the capture and release conditions vary from region-to-region and season-to-season and fluctuate from day-to-day, while different MOFs offer different water adsorption isotherms. Consequently, we propose (1) comprising the adsorbent bed for passive AWH with a mixture of MOFs and (2) tailoring this MOF mixture to particular geographic regions and time frames. We hypothesize each MOF in the mixture can specialize in delivering water under different capture and release conditions, ensuring the adsorbent bed delivers adequate water on every daydespite fluctuations in temperature, humidity, and solar flux. Herein, we develop an optimization framework to determine the total mass and composition of a MOF mixture for comprising a bespoke (i.e., tailored to a declared geographic region and time frame) adsorbent bed for robust (i.e., delivering adequate water every day) passive AWH. We combine weather data in the declared region, equilibrium water adsorption data in the candidate MOFs, and thermodynamic water adsorption models (as a simplifying assumption, we neglect heat and water transfer limitations) to frame a linear program expressing our optimal design principle: adjust the mass of each candidate MOF comprising the adsorbent bed to minimize mass (important for portability and a proxy for cost) while satisfying daily water delivery constraints. Based on case studies in the Chihuahuan and Sonoran Deserts, we find (1) a mixed-MOF adsorbent bed can be, but is not always, lighter (e.g., ≈40% lighter) than the optimized single-MOF counterpart; and (2) the optimal composition and mass of the adsorbent bed differ by both geographic region and time frame. Finally, we visualize the linear program for a reduced problem with a two-dimensional design space to gain intuition, conduct a sensitivity analysis, and compare to an AWH field study. Our work is a starting point for optimizing the composition of bespoke adsorbent beds for robust, passive AWH.

Urea electrooxidation serves as the core of urea-based fuel cells, urea electrolysis for energy generation, and urea-based wastewater treatment for environmental applications. This study emphasizes the development of electrocatalysts made from nickel–cobalt bimetallic sulfide, synthesized through an ultrasonic-assisted hydrothermal synthesis method, focusing on their capacity to oxidize urea under alkaline conditions. The objective was to reduce the onset potential for this reaction. These nickel–cobalt bimetallic sulfide catalysts were characterized by using various techniques, including X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A notable decrease in overpotential was observed: 70 mV for Ni_0.75Co_0.25S and 130 mV for Ni_0.50Co_0.50S, compared to a Ni₁Co₀S electrode. Furthermore, the XPS analysis indicates that the ratio of Ni³⁺/Ni²⁺ is higher for Ni_0.75Co_0.25S than for other combinations, with Ni³⁺ acting as the primary active center for urea electrooxidation. This reduction in the onset potential for urea oxidation and the increase in Ni³⁺ on the nickel–cobalt bimetallic sulfide electrodes reveal significant potential for future applications in urea electrooxidation.

Zeolites are among the most widely employed catalysts in the (petro-)chemical industry. However, due to their elaborate microporous network, they are prone to diffusion limitations and deactivation. Several modification methods have been proposed to overcome these limitations, each exhibiting their benefits. In this work, two of the most promising strategies were combined, i.e., limiting the length of one of the crystal axes during synthesis to achieve a platelike morphology and introducing mesoporosity, creating a hierarchical platelike H-ZSM-5. The platelike morphology was obtained by adding urea as a growth modifier to the synthesis mixture, and mesopores were introduced in the platelike H-ZSM-5 through etching with a NaOH/TPAOH mixture. As a benchmark, the same etching procedure was applied to a commercial ZSM-5 counterpart. These materials were tested in the n-butanol dehydration, where the platelike morphology exhibited an improved catalytic performance, significantly increasing the activity per acid site and stability, and slightly increasing the selectivity toward the butenes. The generation of mesopores in commercial ZSM-5 also increased the activity per acid site but reduced the catalyst’s stability, likely due to an increased amount of Lewis acid sites upon etching. When applying the same modification method to the platelike H-ZSM-5, much larger mesopores and some macropores were observed. These further increased the stability of the catalyst but barely affected the activity per acid site, presumably due to the already optimized catalytic performance of the platelike H-ZSM-5.

This paper proposes an extension of the 1D+1D model for a catalytic monolith filter used in exhaust gas aftertreatment, which allows for the prediction of the effects that soot deposits formed inside the filter wall can have on the catalytic conversion of exhaust gas components. The soot deposits act as an additional barrier between the flowing gas and catalytic sites. The extended model considers three characteristic lengths for diffusion: (i) through the soot deposits, (ii) through the remaining free pores, and (iii) through the catalytic coating. The diffusion resistance of each part is considered based on the corresponding characteristic length and local effective diffusivity. The simulations predict no influence of soot on the reaction onset but an increased slip of unreacted gas above the light-off temperature, particularly at higher flow rates. The predicted trends are consistent with the observations reported in the literature.

Polymeric microparticles (MPs) are valuable drug delivery vehicles for extended-release applications, but current manufacturing techniques present significant challenges in balancing size control with scalability. Industrial synthesis processes provide high throughput but limited precision, while laboratory-scale technologies offer precise control but poor scalability. This study explores Sequential NanoPrecipitation (SNaP), a two-step controlled precipitation process for polymeric microparticle production, to bridge the gap between laboratory precision and industrial scalability. We systematically investigated critical process parameters governing MP formation, focusing on poly(lactic acid) (PLA) MPs stabilized with poly(vinyl alcohol) (PVA). By comparing vortex and impinging jet mixing geometries, we demonstrated that vortex mixing provides superior performance for core assembly, particularly at higher polymer concentrations. We established the influence of delay time (T_d) and core stream concentration (C_core) on particle size, confirming that microparticle assembly follows Smoluchowski diffusion-limited growth kinetics within defined operational boundaries. Through this approach, we achieved precise control over microparticle size (1.6–3.0 μm) with narrow polydispersity. The versatility of SNaP was further demonstrated by the successful formation of MPs with different stabilizers while maintaining consistent size control. Finally, we validated the pharmaceutical relevance of SNaP by encapsulating itraconazole with high efficiency (83–85%) and characterizing its sustained release profile. These findings establish SNaP as a robust, scalable platform for high-quality pharmaceutical microparticle production with superior control over critical quality attributes.

Here, we report a Bayesian optimization (BO)-guided approach to optimize Ni/SiO₂ catalyst synthesis from the reduction of nickel phyllosilicate (rNiPS). Key synthesis parameters─calcination temperature, calcination time, reduction temperature, and reduction time─were tuned to maximize the concentration of exsolved Ni^x+ species and Ni⁰ nanoparticles, which are active sites for levulinic acid (LA) hydrogenation to γ-valerolactone (GVL). Using 15 initial samples of differently synthesized rNiPS catalysts (rNiPS-1 to rNiPS-15) to initiate the BO with Gaussian process regression, we rapidly identified synthesis conditions after three iterations, which increase the combined concentrations of Ni^x+ (x = ∼1.66) and Ni⁰/10 by ∼14% (rNiPS-18) compared to the benchmark. The optimized catalyst’s physicochemical properties, including porosity, crystallinity, reducibility, surface acidity, and local Ni geometry, were analyzed, revealing higher Ni^x+ and lower Ni⁰ concentrations than the benchmark catalyst. Additionally, the turnover frequency of rNiPS-18 for LA hydrogenation to GVL increased nearly 50% compared to that of the benchmark, underscoring BO’s effectiveness in designing Ni catalysts enriched with Ni^x+ and Ni⁰.