Microfluidic Laser-Induced Nucleation of Iron (II,III) Oxide Nanoparticle-Doped Supersaturated Aqueous KCl Solutions.

A capillary-based microfluidic system designed for nonphotochemical laser-induced nucleation (NPLIN) studies coupled with real-time microscopy was used to study NPLIN of iron (II,III) oxide doped aqueous KCl solutions. Supersaturation was achieved by lowering the solution temperature using thermoelectric cooling, and heating was used for the dissolution of crystals downstream to prevent clogging during the flow. The effect of nanoparticle concentration, supersaturation, laser intensity, and filtration was studied.

Interactions of clathrate hydrate promoters sodium dodecyl sulfate and tetrahydrofuran investigated using 1H diffusion nuclear magnetic resonance at hydrate-forming conditions.

Thermodynamic hydrate promoters and kinetic hydrate promoters can be used to reduce the P-T conditions for clathrate hydrate synthesis to decrease the nucleation induction time while increasing growth rates. Two commonly used promoters for hydrate research are tetrahydrofuran (THF) and sodium dodecyl sulfate (SDS), which can increase the overall hydrate promotion when used in tandem as compared to individually. There are several molecular theories regarding how SDS promotes hydrate growth.

The crystal orientation of THF clathrates in nano-confinement by polarized Raman spectroscopy.

Gas hydrates form at high pressure and low temperatures in marine sediments and permafrost regions of the earth. Despite forming in nanoporous structures, gas hydrates have been extensively studied only in bulk. Understanding nucleation and growth of gas hydrates in nonporous confinement can help create ways for storage and utilization as a future energy source.

Carbon dioxide hydrate in a microfluidic device: Phase boundary and crystallization kinetics measurements with micro-Raman spectroscopy.

Various emerging carbon capture technologies depend on being able to reliably and consistently grow carbon dioxide hydrate, particularly in packed media. However, there are limited kinetic data for carbon dioxide hydrates at this length scale. In this work, carbon dioxide hydrate propagation rates and conversion were evaluated in a high pressure silicon microfluidic device.

Pressure-Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride.

Understanding phase transformations in 2D materials can unlock unprecedented developments in nanotechnology, since their unique properties can be dramatically modified by external fields that control the phase change. Here, experiments and simulations are used to investigate the mechanical properties of a 2D diamond boron nitride (BN) phase induced by applying local pressure on atomically thin h-BN on a SiO substrate, at room temperature, and without chemical functionalization. Molecular dynamics (MD) simulations show a metastable local rearrangement of the h-BN atoms into diamond crystal clusters when increasing the indentation pressure.

An automated microfluidic system for the investigation of asphaltene deposition and dissolution in porous media.

Asphaltenes, among the most complex components of crude oil, vary in their molecular structure, composition, and self-assembly in porous media. This complexity makes them challenging in laboratory characterization methods. In the present work, a novel microfluidic device was designed to access in situ transient, high-fidelity information on asphaltene deposition and dissolution within porous media.

Confined methane-water interfacial layers and thickness measurements using in situ Raman spectroscopy.

Gas-liquid interfaces broadly impact our planet, yet confined interfaces behave differently than unconfined ones. We report the role of tangential fluid motion in confined methane-water interfaces. The interfaces are created using microfluidics and investigated by in situ 1D, 2D and 3D Raman spectroscopy.

Flash crystallization kinetics of methane (sI) hydrate in a thermoelectrically-cooled microreactor.

The crystallization kinetics of methane (sI) hydrate were investigated in a thermoelectrically-cooled microreactor with in situ Raman spectroscopy. Step-wise and precise control of the temperature allowed acquisition of reproducible data within minutes, while the nucleation of methane hydrates can take up to 24 h in traditional batch reactors. The propagation rates of methane hydrate (from 3.

Microfluidic investigation of the deposition of asphaltenes in porous media.

The deposition of asphaltenes in porous media, an important problem in science and macromolecular engineering, was for the first time investigated in a transparent packed-bed microreactor (μPBR) with online analytics to generate high-throughput information. Residence time distributions of the μPBR before and after loading with ~29 μm quartz particles were measured using inline UV-Vis spectroscopy. Stable packings of quartz particles with porosity of ~40% and permeability of ~500 mD were obtained.

Deciding whether to go with the flow: evaluating the merits of flow reactors for synthesis.

The fine chemicals and pharmaceutical industries are transforming how their products are manufactured, where economically favorable, from traditional batchwise processes to continuous flow. This evolution is impacting synthetic chemistry on all scales-from the laboratory to full production. This Review discusses the relative merits of batch and micro flow reactors for performing synthetic chemistry in the laboratory.

Teflon-coated silicon microreactors: impact on segmented liquid-liquid multiphase flows.

We describe fluoropolymer modification of silicon microreactors for control of wetting properties in chemical synthesis applications and characterize the impact of the coating on liquid-liquid multiphase flows of solvents and water. Annular flow of nitrogen gas and a Teflon AF (DuPont) dispersion enable controlled evaporation of fluoropolymer solvent, which in turn brings about three-dimensional polymer deposition on microchannel walls. Consequently, the wetting behavior is switched from hydrophilic to hydrophobic.

Microchemical systems for continuous-flow synthesis.

Microchemical systems have evolved rapidly over the last decade with extensive chemistry applications. Such systems enable discovery and development of synthetic routes while simultaneously providing increased understanding of underlying pathways and kinetics. We review basic trends and aspects of microsystems as they relate to continuous-flow microchemical synthesis.

Distillation in microchemical systems using capillary forces and segmented flow.

Distillation is a ubiquitous method of separating liquid mixtures based on differences in volatility. Performing such separations in microfluidic systems is difficult because interfacial forces dominate over gravitational forces. We describe distillation in microchemical systems and present an integrated silicon device capable of separating liquid mixtures based on boiling point differences.

Understanding the dissolution of zeolites.

Scientific knowledge of how zeolites, a unique classification of microporous aluminosilicates, undergo dissolution in aqueous hydrochloric acid solutions is limited. Understanding the dissolution of zeolites is fundamental to a number of processes occurring in nature and throughout industry. To better understand the dissolution process, experiments were carried out establishing that the Si-to-Al ratio controls zeolite framework dissolution, by which the selective removal of aluminum constrains the removal of silicon.

The unique mechanism of analcime dissolution by hydrogen ion attack.

Acidization is the process of injecting acid into porous oil bearing formations to dissolve minerals in the pore space and is a common technique to increase oil production. Analcime is a zeolite which is one of the minerals found in oil reservoirs in the Gulf of Mexico. This mineral is particularly troublesome during the injection of hydrochloric acid during stimulation of the well reservoir because of the precipitation of silicate and analcime dissolution products.