Foaming of CO₂‑Loaded Amine Solvents Degraded Thermally under Stripper Conditions

Foaming of amine solutions remains a problem for natural gas sweetening and post-combustion carbon capture. New amine-based solutions are being developed to replace monoethanolamine (MEA). This work tested the foaminess of MEA and three alternatives (methyldiethanolamine (MDEA), 1-(2-aminoethyl)­piperazine (AEPZ), and 2-amino-2-methyl-1-propanol (AMP)) before and after thermal degradation; two methods were used to describe the foaminess. Foam was only formed after thermal degradation. The first method suggests foaminess, where AEPZ > MDEA > MEA; AMP, by contrast, did not conform to this model and formed a stable foam. The second method, using liquid physical properties, found that solutions that contained more degradation products (MEA, MDEA, AMP) showed different foaminess than those that did not (i.e., changing the chemistry during degradation strongly impacts the foaminess, which is observed). The foaming of these degraded samples demonstrates complexity that cannot be replicated by simple model solutions. Therefore, this study is more representative of the foaming behavior that is observed in industrial cases

Selective Crystallization of Proteins Using Engineered Nanonucleants

This study reports for the first time a detailed experimental investigation of protein crystallization in engineered nanoconfined spaces with both controlled pore diameters and narrow pore size distributions. We propose a systematic approach for controlling the nucleation and crystallization of biological macromolecules based on a relationship between the protein radius of gyration (<i>R</i>_g) and specific pore diameter. A series of nanonucleants with ordered mesopores having narrow pore size distributions were prepared. The templates were tested for proteins ranging in molecular weight from 14 to 450 kDa. Well-formed protein crystals were obtained on only one of the five presented nanonucleants for all protein cases tested, highlighting the unique template selectivity exhibited by these nucleants. In addition, concanavalin A and catalase were both crystallized at ∼2 times lower supersaturation levels than previously reported by any known method. Our observations fully support theoretical studies that predict the enhanced thermodynamic stability of proteins in nanoconfined cavities, including specifically the importance of nucleant pore diameter with respect to protein radius of gyration. The nucleants described here could have major industrial applications for downstream separation and purification of biopharmaceuticals, as well as improved opportunities for the crystallization of complex proteins for structural determination

Crystallization of Proteins at Ultralow Supersaturations Using Novel Three-Dimensional Nanotemplates

A series of novel three-dimensional (3D) nanotemplates which have tuned surface mesoporosity and surface chemistry based on the protein of interest have been developed to facilitate protein crystallization. The crystallization of five model proteins systems is reported at hereto the lowest reported protein or precipitant concentrations. These improvements were only possible due to the combined use of optimum pore sizes with appropriate surface chemistries in the preparation of the 3D nanotemplates. The success of this strategy can be ascribed to the specific design of the ordered nanotemplates which are based on known physicochemical properties of the protein and offer an alternate targeted strategy for protein crystallization in contrast to previous methods based on the use of universal nucleants. The use of protein tuned nanotemplates will potentially open up new opportunities for the crystallization and structure determination of high value proteins, as well as opportunities for their separation and purification in downstream bioprocessing