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1. Low-Temperature Biosurfactants from Polar Microbes

   https://doi.org/10.3390/microorganisms8081183  

   Trudgeon, Benjamin; Dieser, Markus; Balasubramanian, Narayanaganesh; Messmer, Mitch; Foreman, Christine M. (August 2020, Microorganisms)

   Surfactants, both synthetic and natural, are used in a wide range of industrial applications, including the degradation of petroleum hydrocarbons. Organisms from extreme environments are well-adapted to the harsh conditions and represent an exciting avenue of discovery of naturally occurring biosurfactants, yet microorganisms from cold environments have been largely overlooked for their biotechnological potential as biosurfactant producers. In this study, four cold-adapted bacterial isolates from Antarctica are investigated for their ability to produce biosurfactants. Here we report on the physical properties and chemical structure of biosurfactants from the genera Janthinobacterium, Psychrobacter, and Serratia. These organisms were able to grow on diesel, motor oil, and crude oil at 4 °C. Putative identification showed the presence of sophorolipids and rhamnolipids. Emulsion index test (E24) activity ranged from 36.4–66.7%. Oil displacement tests were comparable to 0.1–1.0% sodium dodecyl sulfate (SDS) solutions. Data presented herein are the first report of organisms of the genus Janthinobacterium to produce biosurfactants and their metabolic capabilities to degrade diverse petroleum hydrocarbons. The organisms’ ability to produce biosurfactants and grow on different hydrocarbons as their sole carbon and energy source at low temperatures (4 °C) makes them suitable candidates for the exploration of hydrocarbon bioremediation in low-temperature environments. 

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2. Improving anti-fouling properties of alumina tubular microfiltration membranes through the use of hydrophilic silica nanoparticles for oil/water separation

   https://doi.org/10.1080/01496395.2023.2259605  

   Ghosh, Anirban; Mahmodi, Ghader; Miranda, Michael; Xie, Songpei; Shaw, Madelyn; Krzmarzick, Mark; Lampert, David J.; Kim, Seok-Jhin; Aichele, Clint P. (September 2023, Separation Science and Technology)

   In this study, hydrophilic silica nanoparticles (Si NPs) were used to modify α-alumina tubular membranes to improve their performance in terms of flux, oil rejection, and anti-fouling properties. Our work focuses on enhancing membrane performance, particularly for difficult applications such as produced water treatment. The prepared membranes were applied for oil-in-water emulsion treatment. After coating hydrophilic Si NPs, the oil contact angle improved from 133.8° to 171.4°. To prevent Si NPs from leaching off the surface of α-alumina tubular membranes, polyvinyl alcohol was used to coat the membranes as a pre-treatment step before Si NP modification. After coating the membrane with Si NPs, the roughness of the membrane surface decreased, likely leading to less fouling. After coating Si NPs, Total Organic Carbon rejection increased from 93.1% for pristine α-alumina tubular membranes to 97.7% for silica-modified membranes because of hydrophilic improvements of the modified membranes. The Si NP coating improved the anti-fouling property of membranes with the flux recovery ratio increasing from 71.3% for pristine α-alumina tubular membranes to 85.9% for silica-modified membranes. Scanning Electron Microscopy, Energy- dispersive X-ray spectroscopy, oil contact angle, and Atomic Force Microscopy characterization tests were done. The tests showed successful Si NPs impregnation and altered wettability. 

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3. Interfacial CO ₂ -mediated nanoscale oil transport: from impediment to enhancement

   https://doi.org/10.1039/D0CP03930F  

   Moh, Do Yoon; Fang, Chao; Yin, Xiaolong; Qiao, Rui (October 2020, Physical Chemistry Chemical Physics)

   null (Ed.)

   CO 2 -based enhanced oil recovery is widely practiced. The current understanding of its mechanisms largely focuses on bulk phenomena such as achieving miscibility or reducing oil density and viscosity. Using molecular dynamics simulations, we show that CO 2 adsorption on calcite surfaces impedes decane transport at moderate adsorption density but enhances decane transport when CO 2 adsorption approaches surface saturation. These effects change the decane permeability through 8 nm-wide pores by up to 30% and become negligible only in pores wider than several tens of nanometers. The strongly nonlinear, non-monotonic dependence of decane permeability on CO 2 adsorption is traced to CO 2 's modulation of interfacial structure of long-chain hydrocarbons, and thus the slippage between interfacial hydrocarbon layers and between interfacial CO 2 and hydrocarbon layers. These results highlight a new and critical role of CO 2 -induced interfacial effects in influencing oil recovery from unconventional reservoirs, whose porosity is dominated by nanopores. 

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4. Allyl Sulfides in Garlic Oil Initiate the Formation of Renewable Adhesives

   https://doi.org/10.1039/D3PY00390F  

   Sayer, Kyler B.; Miller, Veronica L.; Merrill, Zackery; Davis, Anthony E.; Jenkins, Courtney L. (January 2023, Polymer Chemistry)

   The development of inverse vulcanization has provided a simple method to create sulfur-based materials. The low cost, ease of synthesis, and variety of applications has led to a rapid expansion of the field. These polysulfides can be synthesized with a wide range of sulfur contents (20-90% S) depending on the desired properties. Garlic essential oil (GEO) has a high sulfur content, which offers the opportunity to replace sulfur, a petroleum byproduct, with a renewable monomer to make materials with moderate sulfur contents. Using a one-pot, solvent-free synthesis, comparable to inverse vulcanization, GEO can be polymerized to create renewable adhesives at temperatures as low as 120 °C with reaction times decreasing at higher temperatures. Here we have explored the composition of garlic oil from a variety of commercial suppliers by NMR. Through simple 1H NMR analysis, the major sulfur-containing compounds of GEO can be identified and differentiated by sulfur rank. These data were used to select garlic oils with varied compositions to examine the impact on the poly(GEO) properties using solubility, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis as well as adhesive performance. GEO was then subjected to different reaction times and temperatures and the degree of polymerization was monitored by 1H NMR. The polysulfides were then evaluated as adhesives at different extents of polymerization to better understand how the reaction conditions impact adhesive performance. The failure mode and mechanical properties of the polymers were analyzed using measurements of maximum adhesion strength and work of adhesion. This study has provided a better understanding of polymers formed from GEO, providing a viable route to developing renewable, S-based materials. 

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5. Single-step assembly of asymmetric vesicles

   https://doi.org/10.1039/c8lc00882e  

   Arriaga, Laura R.; Huang, Yuting; Kim, Shin-Hyun; Aragones, Juan L.; Ziblat, Roy; Koehler, Stephan A.; Weitz, David A. (February 2019, Lab on a Chip)

   Asymmetric vesicles are membranes in which amphiphiles are asymmetrically distributed between each membrane leaflet. This asymmetry dictates chemical and physical properties of these vesicles, enabling their use as more realistic models of biological cell membranes, which also are asymmetric, and improves their potential for drug delivery and cosmetic applications. However, their fabrication is difficult as the self-assembly of amphiphiles always leads to symmetric vesicles. Here, we report the use of water-in-oil-in-oil-in-water triple emulsion drops to direct the assembly of the two leaflets to form asymmetric vesicles. Different compositions of amphiphiles are dissolved in each of the two oil shells of the triple emulsion; the amphiphiles diffuse to the interfaces and adsorb differentially at each of the two oil/water interfaces of the triple emulsion. These middle oil phases dewet from the innermost water cores of the triple emulsion drops, leading to the formation of membranes with degrees of asymmetry up to 70%. The triple emulsion drops are fabricated using capillary microfluidics, enabling production of highly monodisperse drops at rates as high as 300 Hz. Vesicles produced by this method can very efficiently encapsulate many different ingredients; this further enhances the utility of asymmetric vesicles as artificial cells, bioreactors and delivery vehicles. 

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