Solid flow in a Geldart’s group B circulating fluidized bed (CFB) riser is complex, and it exhibits backflow and recirculation in the riser. A single radioactive tracer particle is used to measure the overall and sectional residence time distribution in a CFB riser at a gas velocity of 7.6–9.2 m/s and a solid flux of 100–200 kg/m2s. At the same time, radioactive particle tracking (RPT) data are used to measure the trajectories of the tracer particle and its length distribution at the bottom and middle sections of the riser. Both residence time distribution (RTD) and trajectory length distribution data obtained from RPT and RTD experiments are processed and compared. Results show that the bottom section has higher back mixing than the middle section. The results also show that back mixing in both the sections reduces with an increase in the gas inlet velocity and reduces marginally with an increase in the solid flux. Results confirm that RPT and RTD data are highly correlated and can be used with the same accuracy to quantify the macromixing behavior of any process vessel/reactor.

3D-printed catalyst structures have the potential to broaden reactor operating windows. However, the hydrodynamic aspects associated with these novel catalyst structures have not yet been quantified in detail. This work applies a recently introduced noninvasive, instantaneous, whole-field concentration measurement technique based on infrared transmission to quantify the rate of transverse gas dispersion in 3D-printed logpile structures. Twenty-two structural variations have been investigated at various operating conditions, and the measured transverse gas dispersion has been correlated to the Péclet number and the structures’ porosity and feature size. It is shown that staggered configurations of these logpile structures offer significantly more tunability of the dispersion behavior compared to straight structures. The proposed correlations can be used to facilitate considerations of reactor design and operating windows.

Atmospheric carbon poses an existential threat to civilization via global climate change. Hundreds of gigatonnes of carbon dioxide must be removed from earth’s atmosphere in the next three decades, necessitating a low-cost, energy-efficient process to extract low concentrations of carbon dioxide for conversion to a stable material permanently stored for thousands of years. In this work, the challenge of removing gigatonnes of CO2 is described via the scale of effort and the thermodynamics of collecting and reducing this diffuse chemical, the accumulation of which imparts a substantial entropy penalty on any atmospheric carbon capture process. The methods of CO2 reduction combined with upstream direct air capture (DAC) including absorption, membrane separation, and adsorption are compared with biomass torrefaction and permanent burial (BTB). A Monte Carlo model assesses the mass, energy, and economics of the full process of biomass torrefaction from biomass collection and transport to stable carbon burial to determine that 95% of scenarios could remove carbon for less than $200 per CO2-tonne-equivalent. Torrefied carbon is further discussed for its long-term stability and availability at the scale required to substantially mitigate the threat of climate change.

Catalytic NH3 synthesis is a well-studied reaction, but its use in renewable energy storage is difficult due to the need for small-scale production, requiring greatly reduced operating temperatures and pressures. NH3 inhibition on supported Ru catalysts becomes more prevalent at low temperatures, decreasing the reaction rates. In addition, promoter species are prone to oxidation at lower temperatures, further depressing the reaction rate. In situ NH3 removal techniques have the potential to enhance NH3 synthesis under milder conditions to combat both NH3 inhibition and thermodynamic limitations, while the regeneration of the adsorber can potentially reactivate promoter species. The deactivation event of 5 wt % Ru/CeO2 (3.9 nm average Ru particle size) was first explored in detail, and it was found that slight oxidation of Ce3+ promoter species is the major cause of deactivation at lower temperatures, which is easily restored by high-temperature H2 treatment. Ru/CeO2 was then mixed with zeolite 4A, a substance showing favorable NH3 capacity under mild reaction conditions. In situ adsorption of NH3 significantly increased the reaction rate of Ru/CeO2 at 200 °C with 5 kPa H2 and 75 kPa N2, where the reaction rate increased from 128 to 565 μmol g–1 h–1 even at low H2 conversions of 0.25% (average NH3 yield of 0.01%). The temperature swings that were utilized to measure NH3 uptake on zeolite 4A were also found to provide a reactivation event for Ru/CeO2. In situ NH3 removal went beyond equilibrium limitations, achieving H2 conversions up to 98%. This study sheds light on the kinetics of the use of in situ NH3 removal techniques and provides insight into future designs utilizing similar techniques.

Stable foams that can resist disproportionation for extended periods of time have important applications in a wide range of technological and consumer materials. Yet, legislative initiatives limit the range of surface active materials that can be used for environmental impact reasons. There is a need for technologies to efficiently produce multiphase materials using more eco-friendly components, such as particles, and for which traditional thermodynamics-based processing routes are not necessarily efficient enough. This work describes an innovative foaming technology that can produce ultrastable Pickering-Ramsden foams, with bubbles of micrometer-sized dimensions, through pressure-induced particle densification. Specifically, aqueous nanosilica-stabilized foams are produced by foaming a suspension at subatmospheric pressures, allowing for adsorption of the particles onto large bubbles. This is followed by an increase back to atmospheric pressure, which induces bubble shrinkage and compresses the adsorbed particle interface, forming a strong elastoplastic network that provides mechanical resistance against disproportionation. The foam’s interfacial mechanical properties are quantified to predict the range of processing conditions needed to produce permanently stable foams, and a general stability criterion is derived by considering the interfacial rheological properties under slow, unidirectional compression. Foams that are stable against disproportionation are characterized by interfaces whose mechanical resistance to compressive deformations can withstand their tendency to minimize the interfacial stress by reducing their surface area. Our ultrastable nanosilica foams are tested in real-life applications by introducing them into concrete. In comparison to other commercial air entrainers, our microfoam improves concrete’s freeze–thaw resistance while supplying higher material strength, providing an economically attractive, industrially scalable, and durable alternative for use in real-life applications involving cementitious materials. The applicability of our stability criterion to other rheologically complex interfaces and the versatile nature of our foaming technology enables usage for a broad class of materials, beyond the construction industry.

Slurry loop reactors have been extensively used in chemical industry, for example, ethylene copolymerization. A classical engineering problem is the timely removal of reaction heat which would otherwise cause particle swelling and aggregation, and thus reactor fouling, operation instability, or even blockage, imposing a high safety risk in production. Lack of knowledge on the mesoscale information of particle swelling and aggregation poses great challenge on the prediction of the macroscale behavior. A swelling-dependent two-fluid model was developed and applied for reactor optimization in this work to account for the evolution of mesoscale structures. The simulation resolves the particle aggregation and plug accumulation in the upstream of the pump and the upper horizontal pipe, revealing the fundamental of reactor blockage. The mesoscale structure, when developing to a certain extent, can cause a sharp increase of pump power consumption. This structure can be characterized by the growth and threshold of the plug volume. Based on this mesoscale understanding, a reactor optimization scheme was heuristically proposed to minimize or eliminate the plug regions by employing two pumps and two cycles.

Large-scale biogas plants are a viable source of CH4 and CO2 to be converted efficiently into high-value products. Specifically, production of liquid hydrocarbons can enhance the availability of green fuels while achieving significant CO2 reductions on site. In this study, the production of liquid hydrocarbons is simulated by dry reforming of biogas into lean-hydrogen syngas, further converted in CO hydrogenation and oligomerization reactors. The process was modeled by using CHEMCAD based on published experimental results with the projected feed composition. A high molar feed ratio of CO2/CH4 (>1.7) was set for the reformer to minimize steam requirement while avoiding carbon formation and reaching an optimal H2 to CO molar ratio (0.7). Two options were techno-economically evaluated based on a biogas plant with a capacity of 5000 N m3/h that produces between 13.8 and 15.7 million liters per year of blending stock for transportation fuels. The economics of the process depends mainly on the cost and availability of the biogas. The minimum selling price of the liquid fuels is $1.47/L and $1.37/L for options 1 (once-through conversion of syngas to liquid fuels) and 2 (recycle of tail gas from oligomerization reactor), respectively, and can be significantly reduced in case the biogas throughput is increased to >20 000 N m3/h. Recycling of the tail gas (option 2) yielded higher productivity, resulting in higher carbon yield (77.9% on the basis of methane) and energy efficiency (67.1%). The economic viability of the process can be improved by implementing CO2 tax or other incentives to reduce capital investment. It provides a potential route for efficient conversion of biogas into liquid hydrocarbons to meet the increased demand for renewable fuels as blending stock in the transportation sector while improving the sustainability of the plant.

The energy required to heat, cool, and illuminate buildings continues to increase with growing urbanization, engendering a substantial global carbon footprint for the built environment. Passive modulation of the solar heat gain of buildings through the design of spectrally selective thermochromic fenestration elements holds promise for substantially alleviating energy consumed for climate control and lighting. The binary vanadium(IV) oxide VO2 manifests a robust metal─insulator transition that brings about a pronounced modulation of its near-infrared transmittance in response to thermal activation. As such, VO2 nanocrystals are potentially useful as the active elements of transparent thermochromic films and coatings. Practical applications in retrofitting existing buildings requires the design of workflows to embed thermochromic fillers within industrially viable resins. Here, we describe the dispersion of VO2 nanocrystals within a polyvinyl butyral laminate commonly used in the laminated glass industry as a result of its high optical clarity, toughness, ductility, and strong adhesion to glass. To form high-optical-clarity nanocomposite films, VO2 nanocrystals are encased in a silica shell and functionalized with 3-methacryloxypropyltrimethoxysilane, enabling excellent dispersion of the nanocrystals in PVB through the formation of siloxane linkages and miscibility of the methacrylate group with the random copolymer. Encapsulation, functionalization, and dispersion of the core─shell VO2@SiO2 nanocrystals mitigates both Mie scattering and light scattering from refractive index discontinuities. The nanocomposite laminates exhibit a 22.3% modulation of NIR transmittance with the functionalizing moiety engendering a 77% increase of visible light transmittance as compared to unfunctionalized core─shell particles. The functionalization scheme and workflow demonstrated, here, illustrates a viable approach for integrating thermochromic functionality within laminated glass used for retrofitting buildings.

This study assesses the techno-economic feasibility of an integrated biorefinery based on pineapple processing waste. Xylooligosaccharides, ethanol, xylitol, bromelain, and silage are among the key products of the biorefinery. The economic performance of the processes involved in generating the biorefinery products was assessed based on calculations performed in ASPEN Plus. Seven different scenarios were designed with individual and multiple products and were further evaluated for a plant capacity of 10 tons per hour as the base case. Sensitivity analysis showed that plant capacity and selling price of value-added products were the most important factors that influenced plant economics. The plant capacity twice the base capacity often made the venture economically feasible as in the case of scenarios 1 (production of xylitol and silage) and 7 (production of bromelain, xylitol, and silage) with an NPV of $9.2 million and $8.9 million, respectively. Increasing the selling price of the products by 25% of the base case made scenarios 1 and 6 (production of bromelain, xylitol, ethanol, and silage) economically viable (NPV > 0). A decrease in the price for procurement of pineapple waste from $25/ton to $10/ton made scenario 4 (production of bromelain and silage) profitable with an NPV of $3.3 million and IRR of 42%.

Poly- and perfluoroalkyls (PFAs) are now designated as serious threats to the environment. More than 4700 PFAs, along with their precursors, show a high degree of persistence and long-range spreading in soils and waters causing recalcitrant bioaccumulation in plants, fish, birds, and mammals causing health hazards all along the food chain. Visible-light induced degradation of PFA in pure water using photocatalysts, a potentially sustainable advanced oxidation process, showed exciting results in laboratories for both complete and partial mineralization of these toxins. However, none of the methods and materials have been considered so far for upscaling toward practical applications due to several hard-to-resolve challenges. This Review provides a critical analysis of the recent advancements in photocatalytic remediation of aqueous PFA under visible light irradiation and addresses possible future directions to valorize some of the prospective methods and materials to practical applications.

Froth flotation is the most versatile process in mineral beneficiation, extensively used to concentrate a wide range of minerals. This process comprises mixtures of more or less liberated minerals, water, air, and various chemical reagents, involving a series of intermingled multiphase physical and chemical phenomena in the aqueous environment. Today’s main challenge facing the froth flotation process is to gain atomic-level insights into the properties of its inherent phenomena governing the process performance. While it is often challenging to determine these phenomena via trial-and-error experimentations, molecular modeling approaches not only elicit a deeper understanding of froth flotation but can also assist experimental studies in saving time and budget. Thanks to the rapid development of computer science and advances in high-performance computing (HPC) infrastructures, theoretical/computational chemistry has now matured enough to successfully and gainfully apply to tackle the challenges of complex systems. In mineral processing, however, advanced applications of computational chemistry are increasingly gaining ground and demonstrating merit in addressing these challenges. Accordingly, this contribution aims to encourage mineral scientists, especially those interested in rational reagent design, to become familiarized with the necessary concepts of molecular modeling and to apply similar strategies when studying and tailoring properties at the molecular level. This review also strives to deliver the state-of-the-art integration and application of molecular modeling in froth flotation studies to assist either active researchers in this field to disclose new directions for future research or newcomers to the field to initiate innovative works.

The effects of co-feeding CO2 and methane on the performance of La0.8Sr0.2FeO3 (LSF) were studied with different CO2 concentrations. The reaction was conducted in chemical looping mode at 900 °C and a weight hourly space velocity (WHSV; g methane/g catalyst/h) of 3 h–1 during 15 min reduction (10 mol % methane with 0–1.8% CO2 in nitrogen) and 10 min oxidation (10 mol % oxygen in nitrogen) cycles. Analyses of X-ray diffraction and X-ray photoelectron spectroscopy data of spent materials indicated that CO2 reacts with the oxygen vacancies on the LSF surface during methane reduction, increasing CO selectivity in POM. As the CO2 feed concentration increased to an optimal value (1.6% CO2), the CO selectivity increased to 94%. Under those conditions, the EOR (extent of reduction) of LSF, defined as the amount of oxygen depleted from the lattice, was 0.18–0.15 mmol/min·gcat. Reducing the EOR to 0.09–0.08 mmol/min·gcat (1.8% CO2) led to partial methane combustion. These results were confirmed by altering the operating conditions (WHSV = 2 and 1 h–1, T = 950 °C) and CO2 feed concentrations while extending the reduction time. Operation in an optimal EOR range (0.17–0.10 mmol/min·gcat) that enabled optimal CO selectivity (>90%) was obtained without oxidative regeneration for the 18 h reduction time.

Plastic production has steadily increased worldwide at a staggering pace. The polymer industry is, unfortunately, C-intensive, and accumulation of plastics in the environment has become a major issue. Plastic waste valorization into fresh monomers for production of virgin plastics can reduce both the consumption of fossil feedstocks and the environmental pollution, making the plastic economy more sustainable. Recently, the chemical recycling of plastics has been studied as an innovative solution to achieve a fully sustainable cycle. In this way, plastics are depolymerized to their monomers or/and oligomers appropriate for repolymerization, closing the loop. In this work, PET was depolymerized to its bis(2-hydroxyethyl) terephthalate (BHET) monomer via glycolysis, using ethylene glycol (EG) in the presence of niobia-based catalysts. Using a sulfated niobia catalyst treated at 573 K, we obtained 100% conversion of PET and 85% yield toward BHET at 195 °C in 220 min. This approach allows recycling of the PET at reasonable conditions using an inexpensive and nontoxic material as a catalyst.

Plasma-surface coupling has emerged as a promising approach to perform chemical transformations under mild conditions that are otherwise difficult or impossible thermally. However, a few examples of inexpensive and accessible in situ/operando techniques exist for observing plasma-solid interactions, which has prevented a thorough understanding of underlying surface mechanisms. Here, we provide a simple and adaptable design for a dielectric barrier discharge (DBD) plasma cell capable of interfacing with Fourier transform infrared spectroscopy (FTIR), optical emission spectroscopy (OES), and mass spectrometry (MS) to simultaneously characterize the surface, the plasma phase, and the gas phase, respectively. The system was demonstrated using two example applications: (1) plasma oxidation of primary amine functionalized SBA-15 and (2) catalytic low temperature nitrogen oxidation. The results from application (1) provided direct evidence of a 1% O2/He plasma interacting with the aminosilica surface by selective oxidation of the amino groups to nitro groups without altering the alkyl tether. Application (2) was used to detect the evolution of NOX species bound to both platinum and silica surfaces under plasma stimulation. Together, the experimental results showcase the breadth of possible applications for this device and confirm its potential as an essential tool for conducting research on plasma-surface coupling.

Air pollution is a central problem faced by industries during the production process. The control of this pollution is essential for the environment and living organisms as it creates harmful effects. Biofiltration is a current pollution management strategy that concerns removing odor, volatile organic compounds (VOCs), and other pollutants from the air. Recently, this approach has earned vogue globally due to its low-cost and straightforward technique, effortless function, high reduction efficacy, less energy necessity, and residual consequences not needing additional remedy. There is a critical requirement to consider sustainable machinery to decrease the pollutants arising within air and water sources. For managing these different kinds of pollutant reductions, biofiltration techniques have been utilized. The contaminants are adsorbed upon the medium exterior and are metabolized to benign outcomes through immobilized microbes. Biofiltration-based designs have appeared advantageous in terminating dangerous pollutants from wastewater or contaminated air in recent years. Biofiltration uses the possibilities of microbial approaches (bacteria and fungi) to lessen the broad range of compounds and VOCs. In this review, we have discussed a general introduction based on biofiltration and the classification of air pollutants based on different sources. The history of biofiltration and other mechanisms used in biofiltration techniques have been discussed. Further, the crucial factors of biofilters that affect the performance of biofiltration techniques have been discussed in detail. Finally, we concluded the topic with current challenges and future prospects.

The diversification of coal for its sustainable utilization in producing liquid transportation fuel is inevitable in countries with huge coal reserves. Gasification has been contemplated as one of the most promising thermochemical routes to convert coal into high-quality syngas, which can be utilized to produce liquid hydrocarbons through catalytic Fischer–Tropsch (F-T) synthesis. Liquid transportation fuel production through coal gasification could help deal with environmental challenges and renewable energy development. The present study aims to develop an equilibrium model of a downdraft fixed-bed gasifier using Aspen Plus simulator to predict the syngas compositions obtained from the gasification of high-ash low-rank coal at different operating conditions. Air is used as a gasifying agent in the present study. The model validation is done using published experimental and simulation results from previous investigations. The sensitivity analysis is done to observe the influence of the major operating parameters, such as equivalence ratio (ER), gasification temperature, and moisture content (MC), on the performance of the CL-RMC concerning syngas generation. The gasification performance of CL-RMC is analyzed by defining various performance parameters such as syngas composition, hydrogen-to-carbon monoxide (H2/CO), molar ratio, syngas yield (YSyngas), the lower heating value of syngas (LHVSyngas), cold gas efficiency (CGE), and carbon conversion efficiency (CCE). The combined effects of the major operating parameters are studied through the response surface methodology (RSM) using the design of experiments. The optimized condition of the major operational parameters is determined for a target value of a H2/CO molar ratio of 1 and the maximum CGE and CCE using the multiobjective optimization approach. The high-degree accurate regression model equations were generated for the H2/CO molar ratio, CGE, and CCE using the variance analysis (ANOVA) tool. The optimal conditions of the major operating parameters, i.e., ER, gasification temperature, MC for the H2/CO molar ratio of 1, and the maximum CGE and CCE, are found to be 0.5, 655 °C, and 16.36 wt %, respectively. The corresponding optimal values of CGE and CCE are obtained as 22 and 16.36%, respectively, with a cumulative composite desirability value of 0.7348. The findings of the present investigation can be decisive for future developmental projects in countries concerning the utilization of high-ash low-rank coal in liquid fuel production through the gasification route.

A systematic comparison is demonstrated for the predictions of frontier orbital energies─highest occupied molecular orbital (HOMO) (EH), lowest unoccupied molecular orbital (LUMO) (EL), and energy gap (ΔEHL) of the molecules in the QM9 dataset, where it contains 120k-plus three-dimensional organic molecule structures determined by first-principles simulations. The target molecular properties (EH, EL, and ΔEHL) are predicted using linear regression (LR), machine learning (random forest, RF), and continuous-filter convolutional neural network (SchNET) approaches. LR and RF models built upon various knowledge-based descriptors, being derived from SMILES of the molecules, can provide predictivity of the target properties with the mean absolute errors (MAEs) 4–6 times the chemical accuracy (0.043 eV). The best approach, SchNET, using the graph representation derived from molecular Cartesian coordinates, is confirmed to provide MAEs of EH, EL, and ΔEHL at 0.051, 0.041, and 0.076 eV, respectively. With the introduction of bond-step matrix representation with the SchNET model, the computational cost of dataset preparation can be substantially reduced, and the corresponding MAEs increase moderately to 2–3 times the chemical accuracy. The chemical interpretation of the important descriptors identified in the LR and RF models appears to align with the chemical knowledge of describing these molecular electronic properties but is accompanied with tolerable prediction errors. The combination of bond-step representation and the SchNET model can provide an assessable and balanced option for the high-throughput screening of organic molecules and the development of the data science approach.

We welcome you to the fourth issue of Volume 2 of ACS Engineering Au. Our inaugural editorial (1) introduced ACS Engineering Au and its mission. Next, we highlighted our enhanced focus on technological and engineering aspects of research on chemicals, materials, and energy. (2)ACS Engineering Au is emerging as a premier platform for sharing new research methods and results to facilitate the translation of basic research to practice and application. The scope of ACS Engineering Au is shown schematically in Figure 1 and presented in detail on our journal webpage. Figure 1. Schematic representation of the scope of ACS Engineering Au. The first takeaway from Figure 1 is that the scope is broad and covers virtually everything under the umbrella of chemistry and chemical engineering! This is deliberate and by design. Applied chemistry and chemical engineering are very broad and almost all-encompassing. ACS Engineering Au will be a platform presenting cutting-edge research in these broad areas. This may be counter to the current climate of journal publishing, where more specialized journals are often being developed. Figure 2 shows data on the number of journals in two representative engineering fields, namely, chemical engineering and civil engineering, taken from Journal Citation Reports (Clarivate Analytics, 2022). Please note that the y-axes for the two engineering areas are different and adjusted so that their normalized trajectories look similar. The number of journals is normalized by the number of journals in 2002, and the data for the last 10 years is shown. Figure 2. Change in the number of “Civil Engineering” (Civil: Min = 1.5; Max = 3.5) and “Chemical Engineering” (ChE: Min = 1; Max = 1.55) discipline-specific journals. Data is taken from the Journal Citation Reports (Clarivate, 2022) Whether to restrict the scope of a new journal to a specific area or make it broad is not an easy decision and is based on many different factors and goals. At times, journals are launched as broad platforms for interdisciplinary science; on other occasions, new journals are launched to nurture a small but growing subdiscipline or to capture new audiences for a publisher. Convincing arguments may be made to support the growth of broad or more focused-scope journals. It will be interesting to look at how these trajectories change in the coming years. Three possible trajectories are forecast schematically in Figure 2: consolidation of the number of journals, the number remaining the same, and a further increase in the number of journals. These three projected trajectories represent three possible trends, with no intention of suggesting any quantitative information. The prediction of future trajectories is challenging due to the various factors influencing the future of how we publish chemistry and engineering research. We believe that the growth trend is not sustainable and that there will eventually be a consolidation and reduction in the number of scientific journals. Whether that peak in the number of journals is attained now or will occur some years down the line is open to debate. However, the eventual consolidation and steering toward broad-scope journals appear more likely to us. Developing a broad-scope publishing platform covering applied chemistry and chemical engineering will promote the cross-fertilization of ideas and will allow new emerging topical areas that rely on the same core fundamentals to be easily accommodated. Consider the history of the prominent broad-scope journal, Industrial & Engineering Chemistry Research (I&EC Research). The journal began publishing in 1909, initially under the title Industrial & Engineering Chemistry. It then transformed into four journals focusing on data, fundamentals, processes, and products (Journal of Chemical & Engineering Data, I&EC Fundamentals, I&EC Process Design & Development, and I&EC Product Research & Development) during 1956–1962. In 1986, the latter three journals merged and the word “Research” was added to the title “Industrial & Engineering Chemistry” to form the present-day I&EC Research. We feel that further consolidation, similar to that seen in the case of I&EC Research, may occur in the future, resulting in a reduction in the number of journals and giving rise to more broad-scope journals like ACS Engineering Au. A broad-scope publishing journal platform like ACS Engineering Au is well poised for a future in which open access is the choice of authors interested in boosting the global visibility and reach of their research. The scope of ACS Engineering Au covers that of I&EC Research, Journal of Chemical & Engineering Data, and Energy & Fuels. It thus offers a unique opportunity for the cross-fertilization of ideas from related fields and welcomes science and engineering developments that are truly interdisciplinary. As we are committed to developing ACS Engineering Au with our community of authors, reviewers, and readers, we invite you to share your suggestions on our scope and other aspects of the journal. We consider all feedback carefully and welcome input from the community we serve. We are committed to making ACS Engineering Au the premier fully open access, broad-scope chemical engineering journal. We are also pleased to introduce the fourth issue of Volume 2 of ACS Engineering Au, which contains: Modeling Polyzwitterion-Based Drug Delivery Platforms: A Perspective of the Current State-of-the-Art and Beyond, by Sousa Javan Nikkhah and Matthias Vandichel (DOI: 10.1021/acsengineeringau.2c00008) Catalysis at the Solid–Liquid–Liquid Interface of Water–Oil Pickering Emulsions: A Tutorial Review, by M. Pilar Ruiz and Jimmy A. Faria (DOI: 10.1021/acsengineeringau.2c00010) New Perspectives into Cellulose Fast Pyrolysis Kinetics Using a Py-GC × GC-FID/MS System, by Kevin M. Van Geem and co-workers (DOI: 10.1021/acsengineeringau.2c00006) Discovering Circular Process Solutions through Automated Reaction Network Optimization, by Alexei A. Lapkin and co-workers (DOI: 10.1021/acsengineeringau.2c00002) Optimization of Poly(ethylene terephthalate) Fiber Degradation by Response Surface Methodology Using an Amino Acid Ionic Liquid Catalyst, by Qing Zhou, Xingmei Lu et al. (DOI: 10.1021/acsengineeringau.1c00039) Assessment of Predicting Frontier Orbital Energies for Small Organic Molecules Using Knowledge-Based and Structural Information, by Berlin Chen and Ming-Kang Tsai and co-workers (DOI: 10.1021/acsengineeringau.2c00011) Implementation of a Control Strategy for Hydrodynamics of a Stirred Liquid–Liquid Extraction Column Based on Convolutional Neural Networks, by Norbert Kockmann et al. (DOI: 10.1021/acsengineeringau.2c00014) We sincerely thank all of our authors and reviewers who contributed to this new issue of ACS Engineering Au. Our first few published issues demonstrate the breadth of the scope of the journal, and we appreciate the support from the community in the first 18 months of the journal. We thank Amelia Newman (Managing Editor, ACS Engineering Au) for gathering the data and for useful discussions. This article references 2 other publications. This article has not yet been cited by other publications. Figure 1. Schematic representation of the scope of ACS Engineering Au. Figure 2. Change in the number of “Civil Engineering” (Civil: Min = 1.5; Max = 3.5) and “Chemical Engineering” (ChE: Min = 1; Max = 1.55) discipline-specific journals. Data is taken from the Journal Citation Reports (Clarivate, 2022) This article references 2 other publications.

Amine resins are frequently studied to capture CO2 from industrial emission sources and air. Polyethylene imine (PEI) is a typical example showing relatively high CO2 uptake and not too energy demanding desorption of CO2. For practical application, its oxidation stability is of great importance. In this DFT study, the ultimate oxidation stability of the two forms of PEI, linear PEI (LPEI) and branched PEI (BPEI), is investigated. First, the oxidation stability order for amines was determined using small amine clusters: primary > secondary > tertiary amines. Using LPEI and BPEI structure-related clusters, it turned out that under optimal conditions, the formation of α-amino hydroperoxide of PEI is the rate-determining step. Optimal conditions are the total absence of initiators like transition-metal ions, NOx, O3, or hydrocarbons and the presence of H2O and CO2. All computational results are in line with experimental results.

Bioinspired silica (BIS) has received unmatched attention in recent times owing to its green synthesis, which offers a scalable, sustainable, and economical method to produce high-value silica for a wide range of applications, including catalysis, environmental remediation, biomedical, and energy storage. To scale-up BIS synthesis, it is critically important to understand how mixing affects the reaction at different scales. In particular, successful scale-up can be achieved if mixing time is measured, modeled, and kept constant across different production scales. To this end, a new image analysis technique was developed using pH, as one of the key parameters, to monitor the reaction and the mixing. Specifically, the technique involved image analysis of color (pH) change using a custom-written algorithm to produce a detailed pH map. The degree of mixing and mixing time were determined from this analysis for different impeller speeds and feed injection locations. Cross validation of the mean pH of selected frames with measurements using a pH calibration demonstrated the reliability of the image processing technique. The results suggest that the bioinspired silica formation is controlled by meso- and, to a lesser extent, micromixing. Based on the new data from this investigation, a mixing time correlation is developed as a function of Reynolds number─the first of a kind for green nanomaterials. Further, we correlated the effects of mixing conditions on the reaction and the product. These results provide valuable insights into the scale-up to enable sustainable manufacturing of BIS and other nanomaterials.