Search

Herein we report the design of an upper-level hybrid laboratory course in the area of applied biopharmaceuticals, which has high scheduling flexibility, and utilizes both virtual and in-person educational elements to enhance students' learning experience. This newly developed course applies chemical engineering knowledge, practical and theoretical, in the bioprocess and pharmaceutical industry, including crystallization, chromatography, and mass transport. During the COVID-19 pandemic, we transferred this lab course to a completely virtual mode during midsemester of Spring 2020. Despite the lack of in-person experiments during the second half of the semester, we introduced various additional elements including modeling, simulation, literature review, and added lectures to the virtual version of the course to improve students' learning experience. These additional elements introduced during the virtual period enriched the course content and exposed students to more advanced applications of the knowledge in this course, which can be implemented in future hybrid modes. Although the student performance on quizzes and lab reports remained consistent after the transition to online format, the instructors noticed students struggling with data mined from previous groups. The root cause of this was not being able to create and observe their own data in real time, which could be improved by developing better remote data collection methods. Another lesson we learned during this experience is the value of keeping an experimental video archive for all of our laboratory modules, regardless of plans for remote learning.

The synthesis of high-purity precipitated calcium carbonate (PCC) is responsible for approximately 30% of the global annual production of calcium carbonates. As increasing carbon capture utilization and storage (CCUS) facilities come online to mitigate anthropogenic emissions, PCC production is expected to grow through carbon mineralization production pathways. Tuning the PCC morphological and crystal structure properties will largely dictate the potential downstream uses of the carbonate products; thus, increased research is needed into process design considerations for crystal habit modification of PCC. Of the three anhydrous polymorphic forms of PCC, aragonite shows great promise in applications as a filler material or flow-modifier due to its unique needle-like structure. Synthetic aragonite is generally produced at elevated reaction temperatures (60–80 °C), however alternative crystallization methods can be applied to reduce this energy barrier and better control crystal production. Herein, we compare the crystallization of aragonite in both a batch and semi-continuous crystallizers using a model system (e.g., CaCl2 and K2CO3) to elucidate the effect of mixing and saturation in relation to PCC crystal morphology. Seeding of aragonite is also utilized as a method to better control the PCC production process and lower the required synthesis temperature to 25–40 °C. Finally, these methods are extended to a Ca-rich leachate from waste hydrated cement paste (HCP) for comparison with the model system. The produced aragonite is reincorporated into new cement and tested for its potential hydration and rheological advantages. Overall, this work motivates the use of alternative crystallization methods to promote polymorph control for niche CCUS applications, especially cement decarbonization. [ABSTRACT FROM AUTHOR]

Tandem catalysis involving simultaneous dihydrogen generation from a hydrogen carrier and substrate reduction on a heterogeneous catalyst provides unique opportunities for green chemistry synthesis under mild reaction conditions. However, in traditional batch conditions for nitro reductions, excess hydrogen is often necessary to achieve full conversion and thermal management on scale-up is a safety issue due to large heats of reaction and adiabatic temperature rise. Herein, we report a continuous-flow strategy to maximize hydrogen utilization efficiency (HUE) and improve reaction safety in tandem nitro-reduction reactions, using stoichiometric amounts of ammonia borane (AB) in methanol as the hydrogen source with Pd/C catalyst. This strategy provides a full conversion of nitrobenzene to highly pure aniline in 15 s, with only air cooling needed. In comparison, a batch reaction with stoichiometric AB only reaches a 42% yield of aniline over Pd/C after 30 min. The space–time yield of aniline in a flow system (92.07 g L−1 min−1) is substantially higher than that in a batch reaction (0.13 g L−1 min−1). The tandem reaction set in a flow configuration was simulated with commercial software (Aspen Plus v8.8) enabling scale-up, safe operation, and optimization of energy use. Our tandem flow system with a full HUE, good thermal management, and excellent catalytic efficiency provides a practical way for the green chemistry synthesis of anilines. [ABSTRACT FROM AUTHOR]