Selecting An Optimum Hydrophobic Groups From Vegetable Oil Derivative for Surfactants used in Enhanced Oil Recovery

The need for fossil fuels which tends to increase without an increase in oil production has become the main factor in applying the Enhanced Oil Recovery (EOR) methods in the mature oil field. Chemical injection using surfactants is one of the EOR technologies that has been proved to be able to increase oil recovery. In this study, surfactants were synthesized using a fatty acid derived from palm oil as hydrophobic group and polyethylene-glycol as hydrophilic group. The use of vegetable oil as raw material is possible because it is abundant and environmentally friendly. Esterification of nonionic surfactant was performed by utilizing the azeotrope technique (Toluena-H2O) between fatty acid (oleic, stearic, palmitic and lauric acids) and polyethylene glycol (PEG) (200, 300, 400, 600, 1000, and 1500). The reaction was optimized with various moles of fatty acid and PEG equivalents (1:1,1; 1:2,5; 1;3) and various time reaction. Product surfactant was characterized by thin-layer chromatography (TLC) to determine the optimum condition and reaction conversion. The molecular structure of the surfactant was confirmed by 1H NMR. Nonionic surfactant was then analyzed by measuring the interfacial tension (IFT) of oil and water. The results showed that the optimum conditions to obtain the lowest IFT were achieved by reacting hydrophobic groups of oleic acid and hydrophilic groups of PEG-400 at an equivalent mole ratio of 1: 3 and a reaction time of 5 hours. Oleic PEG-400 surfactant was able to decrease the IFT of oil and water as low as 10-4 dyne/cm in brine salinity condition of 18000 ppm and oil 34,39 OAPI. The results was then used to design the synthesis of vegetable surfactant oil with various carbon chain lengths and functional groups as an EOR surfactant hydrophobic group.

Rheological Study of Gemini Surfactants with Amide Groups

In the present study, the micelle aggregation numbers and hydrodynamic radius distributions of the gemini surfactants (abbreviated as Cm-(EO)n-E-Cm (m = 12–16, n = 1, 2)) were investigated by fluorescence spectroscopy and dynamic light scattering (DLS). The rheological properties of these surfactants were determined using a rheometer. The Surfactants C14-(EO)-E-C14 and C16-(EO)-E-C16 formed worm-like micelles at a concentration of 200 mmol/L. It was found that longer hydrophobic chains or shorter linkage groups promoted the growth of worm-like micelles. Then, the influence of the inorganic salt NaBr and the organic salt sodium salicylate (NaSal) on the formation and properties of wormlike micelles in aqueous C16-(EO)-E-C16 solutions at a surfactant concentration of 20 mmol/L was investigated. The results showed that NaSal could penetrate deeper into the hydrophobic group of the micelle due to its good hydrophobic interaction, which promoted micelle growth and resulted in worm-like micelles. In addition, the tested systems showed a Maxwell behavior at lower frequencies, but deviated from the Maxwell mode at higher frequencies. Finally, the formation of worm-like micelles was also verified by micro polarity measurements.

Formation of asymmetric belt-like aggregates from a bio-based surfactant derived from dehydroabietic acid

The morphology and physicochemical properties of ordered molecular aggregates are closely related to surfactant molecules. Herein, a rosin-based amine oxide surfactant containing a large hydrophobic group (abbreviated R-10-AO) was synthesized...

Preparation and Anti-frost Performance of PDMS-SiO2/SS Superhydrophobic Coating

Polydimethylsiloxane modified SiO2/organic silicon sol (PDMS-SiO2/SS) hybrid coating was synthesized via a simple two-step modification route. The nanoparticles (NPs) of PDMS-SiO2 were synthesized through a high temperature dehydration reaction by using silica and excessive PDMS. The NPs lapped with each other and formed a branch and tendril structure. Organic silicon sol (SS) added as basement introduced a hydrophobic group and protected the structure of the NPs. The PDMS-SiO2/SS hybrid coating exhibits a superhydrophobic performance with a maximum water contact angle of 152.82°. The frost test was carried out on a refrigerator evaporator, and the results showed that the coating did not merely delay the frost crystal time about 113 min but also increased the frost layer process time. Meanwhile, the defrosted water droplets rolled off from the coated surface easily which is a benefit for frost suppression performance of the next refrigeration cycle.

Synthesis and Characterization of Cholesteryl Conjugated Lysozyme (CHLysozyme)

Hydrophobic interaction is important for protein conformation. Conjugation of a hydrophobic group can introduce intermolecular hydrophobic contacts that can be contained within the molecule. It is possible that a strongly folded state can be formed in solution compared with the native state. In this study, we synthesized cholesteryl conjugated lysozyme (CHLysozyme) using lysozyme and cholesterol as the model protein and hydrophobic group, respectively. Cholesteryl conjugation to lysozyme was confirmed by nuclear-magnetic resonance. Differential-scanning calorimetry suggested that CHLysozyme was folded in solution. CHLysozyme secondary structure was similar to lysozyme, although circular dichroism spectra indicated differences to the tertiary structure. Fluorescence measurements revealed a significant increase in the hydrophobic surface of CHLysozyme compared with that of lysozyme; CHLysozyme self-associated by hydrophobic interaction of the conjugated cholesterol but the hydrophobic surface of CHLysozyme decreased with time. The results suggested that hydrophobic interaction changed from intramolecular interaction to an intermolecular interaction. Furthermore, the relative activity of CHLysozyme to lysozyme increased with time. Therefore, CHLysozyme likely forms a folded state with an extended durability of activity. Moreover, lysozyme was denatured in 100% DMSO but the local environment of tryptophan in CHLysozyme was similar to that of a native lysozyme. Thus, this study suggests that protein solution stability and resistance to organic solvents may be improved by conjugation of a hydrophobic group.

A zwitterionic polymer containing a hydrophobic group: enhanced rheological properties

A zwitterionic polymer containing a hydrophobic long chain, named MANPS, was independently developed by free radical solution polymerization.