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- Volume 9, 2018
Annual Review of Chemical and Biomolecular Engineering - Volume 9, 2018
Volume 9, 2018
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An Autobiography of Ronald W. Rousseau
Vol. 9 (2018), pp. 1–16More LessThis article provides a synopsis of my professional career, from the decision to study chemical engineering to leadership of one of the top academic programs in that field. I describe how I chose to devote my research to phenomena associated with crystallization as practiced for separation and purification and then made the transition to leader of an academic program. Embedded in the coverage are descriptions of research advances coming from exploration of secondary nucleation, especially how collisions of crystals in supersaturated environments dominate the behavior of industrially relevant crystallization processes. I recount some of the challenges associated with becoming a school chair and how the program I led grew. The story illuminates the contributions of my many mentors, colleagues, and students.
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Single- to Few-Layered, Graphene-Based Separation Membranes
Vol. 9 (2018), pp. 17–39More LessTwo-dimensional, graphene-based materials have attracted great attention as a new membrane building block, primarily owing to their potential to make the thinnest possible membranes and thus provide the highest permeance for effective sieving, assuming comparable porosity to conventional membranes and uniform molecular-sized pores. However, a great challenge exists to fabricate large-area, single-layered graphene or graphene oxide (GO) membranes that have negligible undesired transport pathways, such as grain boundaries, tears, and cracks. Therefore, model systems, such as a single flake or nanochannels between graphene or GO flakes, have been studied via both simulations and experiments to explore the transport mechanisms and separation potential of graphene-based membranes. This article critically reviews literature related to single- to few-layered graphene and GO membranes, from material synthesis and characteristics, fundamental membrane structures, and transport mechanisms to potential separation applications. Knowledge gaps between science and engineering in this new field and future opportunities for practical separation applications are also discussed.
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From Multiscale to Mesoscience: Addressing Mesoscales in Mesoregimes of Different Levels
Jinghai Li, and Wenlai HuangVol. 9 (2018), pp. 41–60More LessThis review covers three decades of research on mesoscale phenomena in chemical engineering, from the energy minimization multiscale (EMMS) model specific for gas–solid fluidization to a general principle of compromise in competition between dominant mechanisms, leading to the proposed concept of mesoscience. First, the concept of mesoscales is reviewed with respect to their commonality, diversity, and misunderstanding in different fields. Then, the evolution from the EMMS model to the EMMS principle common to all mesoscales is described to show the rationale of mesoscience referring to both mesoscales and mesoregimes. Finally, the potential universality of mesoscience and its importance, particularly to enable virtual process engineering (VPE) by realizing the consistency of logic and structure between the problem, the model, the software, and the computer, are discussed. The review concludes by illustrating possible case studies to collect more evidence and a potential framework for mesoscience.
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Toward Constitutive Models for Momentum, Species, and Energy Transport in Gas–Particle Flows
Vol. 9 (2018), pp. 61–81More LessAs multiscale structures are inherent in multiphase flows, constitutive models employed in conjunction with transport equations for momentum, species, and energy are scale dependent. We suggest that this scale dependency can be better quantified through deep learning techniques and formulation of transport equations for additional quantities such as drift velocity and analogies for species, energy, and momentum transfer. How one should incorporate interparticle forces, which arise through van der Waals interaction, dynamic liquid bridges between wet particles, and tribocharging, in multiscale models warrants further study. Development of multiscale models that account for all the known interactions would improve confidence in the use of simulations to explore design options, decrease the number of pilot-scale experiments, and accelerate commercialization of new technologies.
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Stable Radical Materials for Energy Applications
Vol. 9 (2018), pp. 83–103More LessAlthough less studied than their closed-shell counterparts, materials containing stable open-shell chemistries have played a key role in many energy storage and energy conversion devices. In particular, the oxidation-reduction (redox) properties of these stable radicals have made them a substantial contributor to the progress of organic batteries. Moreover, the use of radical-based materials in photovoltaic devices and thermoelectric systems has allowed for these emerging molecules to have impacts in the energy conversion realm. Additionally, the unique doublet states of radical-based materials provide access to otherwise inaccessible spin states in optoelectronic devices, offering many new opportunities for efficient usage of energy in light-emitting devices. Here, we review the current state of the art regarding the molecular design, synthesis, and application of stable radicals in these energy-related applications. Finally, we point to fundamental and applied arenas of future promise for these designer open-shell molecules, which have only just begun to be evaluated in full.
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Biodegradable Polymeric Nanoparticles for Therapeutic Cancer Treatments
Vol. 9 (2018), pp. 105–127More LessPolymeric nanoparticles have tremendous potential to improve the efficacy of therapeutic cancer treatments by facilitating targeted delivery to a desired site. The physical and chemical properties of polymers can be tuned to accomplish delivery across the multiple biological barriers required to reach diverse subsets of cells. The use of biodegradable polymers as nanocarriers is especially attractive, as these materials can be designed to break down in physiological conditions and engineered to exhibit triggered functionality when at a particular location or activated by an external source. We present how biodegradable polymers can be engineered as drug delivery systems to target the tumor microenvironment in multiple ways. These nanomedicines can target cancer cells directly, the blood vessels that supply the nutrients and oxygen that support tumor growth, and immune cells to promote anticancer immunotherapy.
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Critical Comparison of Structured Contactors for Adsorption-Based Gas Separations
Vol. 9 (2018), pp. 129–152More LessRecent advances in adsorptive gas separations have focused on the development of porous materials with high operating capacity and selectivity, useful parameters that provide early guidance during the development of new materials. Although this material-focused work is necessary to advance the state of the art in adsorption science and engineering, a substantial problem remains: how to integrate these materials into a fixed bed to efficiently utilize the separation. Structured sorbent contactors can help manage kinetic and engineering factors associated with the separation, including pressure drop, sorption enthalpy effects, and external heat integration (for temperature swing adsorption, or TSA). In this review, we discuss monoliths and fiber sorbents as the two main classes of structured sorbent contactors; recent developments in their manufacture; advantages and disadvantages of each structure relative to each other and to pellet packed beds; recent developments in system modeling; and finally, critical needs in this area of research.
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The Energy Future
Vol. 9 (2018), pp. 153–174More LessThe foreseeable energy future will be driven by economics of known technologies and the desire to reduce CO2 emissions to the atmosphere. Renewable energy options are compared with each other and with the use of fossil fuels with carbon capture and sequestration (CCS). Economic analysis is used to determine the best of several alternatives. One can disagree on the detailed costs, including externalities such as climate change and air and water pollution. But the differences in capital and operating costs between known technologies are so significant that one can draw clear conclusions. Results show that renewable energy cannot compete with fossil fuels on a cost basis alone because energy is intrinsic to the molecule, except for hydroelectricity. However, fossil fuels are implicated in climate change. Using renewable energy exclusively, including transportation and electricity needs, could reduce the standard of living in the United States by 43% to 62%, which would correspond to the level in about 1970. If capture and sequester of CO2 are implemented, the cost of using fossil fuels will increase, but they beat renewable energy handily as an economic way to produce clean energy.
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Confined Flow: Consequences and Implications for Bacteria and Biofilms
Vol. 9 (2018), pp. 175–200More LessBacteria overwhelmingly live in geometrically confined habitats that feature small pores or cavities, narrow channels, or nearby interfaces. Fluid flows through these confined habitats are ubiquitous in both natural and artificial environments colonized by bacteria. Moreover, these flows occur on time and length scales comparable to those associated with motility of bacteria and with the formation and growth of biofilms, which are surface-associated communities that house the vast majority of bacteria to protect them from host and environmental stresses. This review describes the emerging understanding of how flow near surfaces and within channels and pores alters physical processes that control how bacteria disperse, attach to surfaces, and form biofilms. This understanding will inform the development and deployment of technologies for drug delivery, water treatment, and antifouling coatings and guide the structuring of bacterial consortia for production of chemicals and pharmaceuticals.
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Molecular Modelling for Reactor Design
Vol. 9 (2018), pp. 201–227More LessChemical reactor modelling based on insights and data on a molecular level has become reality over the last few years. Multiscale models describing elementary reaction steps and full microkinetic schemes, pore structures, multicomponent adsorption and diffusion inside pores, and entire reactors have been presented. Quantum mechanical (QM) approaches, molecular simulations (Monte Carlo and molecular dynamics), and continuum equations have been employed for this purpose. Some recent developments in these approaches are presented, in particular time-dependent QM methods, calculation of van der Waals forces, new approaches for force field generation, automatic setup of reaction schemes, and pore modelling. Multiscale simulations are discussed. Applications of these approaches to heterogeneous catalysis are demonstrated for examples that have found growing interest over the last few years, such as metal-support interactions, influence of pore geometry on reactions, noncovalent bonding, reaction dynamics, dynamic changes in catalyst nanoparticle structure, electrocatalysis, solvent effects in catalysis, and multiscale modelling.
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Biomolecular Ultrasound and Sonogenetics
Vol. 9 (2018), pp. 229–252More LessVisualizing and modulating molecular and cellular processes occurring deep within living organisms is fundamental to our study of basic biology and disease. Currently, the most sophisticated tools available to dynamically monitor and control cellular events rely on light-responsive proteins, which are difficult to use outside of optically transparent model systems, cultured cells, or surgically accessed regions owing to strong scattering of light by biological tissue. In contrast, ultrasound is a widely used medical imaging and therapeutic modality that enables the observation and perturbation of internal anatomy and physiology but has historically had limited ability to monitor and control specific cellular processes. Recent advances are beginning to address this limitation through the development of biomolecular tools that allow ultrasound to connect directly to cellular functions such as gene expression. Driven by the discovery and engineering of new contrast agents, reporter genes, and bioswitches, the nascent field of biomolecular ultrasound carries a wave of exciting opportunities.
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Continuous Manufacturing in Pharmaceutical Process Development and Manufacturing
Vol. 9 (2018), pp. 253–281More LessThe pharmaceutical industry has found new applications for the use of continuous processing for the manufacture of new therapies currently in development. The transformation has been encouraged by regulatory bodies as well as driven by cost reduction, decreased development cycles, access to new chemistries not practical in batch, improved safety, flexible manufacturing platforms, and improved product quality assurance. The transformation from batch to continuous manufacturing processing is the focus of this review. The review is limited to small, chemically synthesized organic molecules and encompasses the manufacture of both active pharmaceutical ingredients (APIs) and the subsequent drug product. Continuous drug product is currently used in approved processes. A few examples of production of APIs under current good manufacturing practice conditions using continuous processing steps have been published in the past five years, but they are lagging behind continuous drug product with respect to regulatory filings.
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Crystal Engineering for Catalysis
Vol. 9 (2018), pp. 283–309More LessCrystal engineering relies upon the ability to predictively control intermolecular interactions during the assembly of crystalline materials in a manner that leads to a desired (and predetermined) set of properties. Economics, scalability, and ease of design must be leveraged with techniques that manipulate the thermodynamics and kinetics of crystal nucleation and growth. It is often challenging to exact simultaneous control over multiple physicochemical properties, such as crystal size, habit, chirality, polymorph, and composition. Engineered materials often rely upon postsynthesis (top-down) processes to introduce properties that would otherwise be challenging to attain through direct (bottom-up) approaches. We discuss the application of crystal engineering to heterogeneous catalysts with a focus on four general themes: (a) tailored nanocrystal size, (b) controlled environments surrounding active sites, (c) tuned morphology with well-defined facets, and (d) hierarchical materials with disparate pore size and active site distributions. We focus on nonporous materials, including metals and metal oxides, and two classes of porous materials: zeolites and metal organic frameworks. We review novel synthesis methods involving synergistic experimental and computational design approaches, the challenges facing catalyst development, and opportunities for future advancement in crystal engineering.
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Engineered Ribosomes for Basic Science and Synthetic Biology
Vol. 9 (2018), pp. 311–340More LessThe ribosome is the cell's factory for protein synthesis. With protein synthesis rates of up to 20 amino acids per second and at an accuracy of 99.99%, the extraordinary catalytic capacity of the bacterial translation machinery has attracted extensive efforts to engineer, reconstruct, and repurpose it for biochemical studies and novel functions. Despite these efforts, the potential for harnessing the translation apparatus to manufacture bio-based products beyond natural limits remains underexploited, and fundamental constraints on the chemistry that the ribosome's RNA-based active site can carry out are unknown. This review aims to cover the past and present advances in ribosome design and engineering to understand the fundamental biology of the ribosome to facilitate the construction of synthetic manufacturing machines. The prospects for the development of engineered, or designer, ribosomes for novel polymer synthesis are reviewed, future challenges are considered, and promising advances in a variety of applications are discussed.
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Shale Gas Implications for C2-C3 Olefin Production: Incumbent and Future Technology
Vol. 9 (2018), pp. 341–364More LessSubstantial natural gas liquids recovery from tight shale formations has produced a significant boon for the US chemical industry. As fracking technology improves, shale liquids may represent the same for other geographies. As with any major industry disruption, the advent of shale resources permits both the chemical industry and the community an excellent opportunity to have open, foundational discussions on how both public and private institutions should research, develop, and utilize these resources most sustainably. This review summarizes current chemical industry processes that use ethane and propane from shale gas liquids to produce the two primary chemical olefins of the industry: ethylene and propylene. It also discusses simplified techno-economics related to olefins production from an industry perspective, attempting to provide a mutually beneficial context in which to discuss the next generation of sustainable olefin process development.
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Nanoscale Optical Microscopy and Spectroscopy Using Near-Field Probes
Vol. 9 (2018), pp. 365–387More LessLight-matter interactions can provide a wealth of detailed information about the structural, electronic, optical, and chemical properties of materials through various excitation and scattering processes that occur over different length, energy, and timescales. Unfortunately, the wavelike nature of light limits the achievable spatial resolution for interrogation and imaging of materials to roughly λ/2 because of diffraction. Scanning near-field optical microscopy (SNOM) breaks this diffraction limit by coupling light to nanostructures that are specifically designed to manipulate, enhance, and/or extract optical signals from very small regions of space. Progress in the SNOM field over the past 30 years has led to the development of many methods to optically characterize materials at lateral spatial resolutions well below 100 nm. We review these exciting developments and demonstrate how SNOM is truly extending optical imaging and spectroscopy to the nanoscale.
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Advances in Multicompartment Mesoporous Silica Micro/Nanoparticles for Theranostic Applications
Vol. 9 (2018), pp. 389–411More LessMesoporous silica nanoparticles (MSNs) are promising functional nanomaterials for a variety of biomedical applications, such as bioimaging, drug/gene delivery, and cancer therapy. This is due to their low density, low toxicity, high biocompatibility, large specific surface areas, and excellent thermal and mechanical stability. The past decade has seen rapid advances in the development of MSNs with multiple compartments. These include hierarchical porous structures and core-shell, yolk-shell, and Janus structured particles for efficient diagnosis and therapeutic applications. We review advances in this area, covering the categories of multicompartment MSNs and their synthesis methods, with an emphasis on hierarchical structures and the incorporation of multiple functions. We classify multicompartment mesoporous silica micro/nanostructures, ranging from core-shell and yolk-shell structures to Janus and raspberry-like nanoparticles, and discuss their synthesis methods. We review applications of these multicompartment MSNs, including bioimaging, targeted drug/gene delivery, chemotherapy, phototherapy, and in vitro diagnostics. We also highlight the latest trends and new opportunities.
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Microkinetic Analysis and Scaling Relations for Catalyst Design
Vol. 9 (2018), pp. 413–450More LessMicrokinetic analysis plays an important role in catalyst design because it provides insight into the fundamental surface chemistry that controls catalyst performance. In this review, we summarize the development of microkinetic models and the inclusion of scaling relationships in these models. We discuss the importance of achieving stoichiometric and thermodynamic consistency in developing microkinetic models. We also outline how analysis of the maximum rates of elementary steps can be used to determine which transition states and adsorbed intermediates are kinetically significant, allowing the derivation of general reaction kinetics rate expressions in terms of changes in binding energies of the relevant transition states and intermediates. Through these analyses, we present how to predict optimal surface coverages and binding energies of adsorbed species, as well as the extent of potential rate improvement for a catalytic system. For systems in which the extent of potential rate improvement is small because of limitations imposed by scaling relations, different approaches, including the addition of promoters and formation of catalysts containing multiple functionalities, can be used to break the scaling relations and obtain further rate enhancement.
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