Synthesis and surface activity properties of symmetric double chains alkylbetaine surfactants derived from s-triazine

One-Step Synthesis of New Amphiphilic Nonionic Surfactants Based on Alkylamine and Poly(ethylene glycol) Dimethacrylate for Demulsification of Arabian Heavy Crude Oil Emulsions

New non-ionic surfactants based on alkylamine and poly(ethylene glycol) dimethacrylate were synthesized by one-step Aza-Michael addition reaction. The surfactants' chemical compositions, surface and interfacial activities, micellization, and zeta potential were characterized. Their surface and interfacial activities recommended the application as demulsifiers for water in Arabian heavy oil emulsions (w/o). The demulsification of this type of emulsion has attracted researchers' attention because of its high stability with water droplets in the microscale. The outcome of using the prepared surfactants showed high performance as emulsion breakers, as the demulsification efficiency reached 100% for w/o emulsions with different water to oil ratios (50:50, 30:70, and 10:90).

Synthesis, Characterization and Application of Novel Cationic Surfactants as Antibacterial Agents

It is of great necessity to develop new antimicrobial agents to overcome the accelerated increment in drug-resistant bacteria. The main aim of this work is to manufacture two cationic surfactants, QHETA-9 and QHETA-14, based on quaternary hexamethylenetetramine with long alkyl chains (C-9 and C-14) by simple one-step alkylation reaction. These surfactants were characterized by analytical and statistical data, including FTIR, 1H NMR, 13C NMR and DLS. The antibacterial activities of QHETA-9 and QHETA-14 against some pathogenic bacterial strains were tested using agar disk diffusion method. The results exhibited that QHETA-14 has higher antibacterial activity than that of QHETA-9. It displayed inhibitory zone values for Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis, as Gram-positive bacteria, of 22.7, 21.5 and 25.9 mm, respectively, at 200 μg/disk. Meanwhile, it recorded inhibition zone values of 17.5, 25.2 and 23.8 mm for Escherichia coli, Agrobacterium tumefaciens and Erwinia carotovora, respectively, at 200 μg/disk. As a result, the current investigation verified that the antibacterial properties of QHETA-14 were greater than those of QHETA-9 due to the increase in the length of the alkyl chain. It is clear that QHETA-14 has the potential to be used as an antibacterial agent against bacteria that cause nosocomial infections and food poisoning diseases.

One-Step Synthesis of Amphiphilic Nonylphenol Polyethyleneimine for Demulsification of Water in Heavy Crude Oil Emulsions

The demulsification of water-in-heavy crude oil emulsion with water droplet size in the microscale has drawn great attention because of their high stability and difficulty of separation. In the present work, a series of ethylene amine-based demulsifiers were prepared in one step through the interaction of pentaethylene hexamine, tetraethylene pentamine, and triethylene tetramene with glycidyl 4-nonylphenyl ether. The amphiphilic polyethyleneimine (APEI) abbreviated as DNPA-6, DNPA-5, and DNPA-4 were prepared to adjust their hydrophile-lipophile balances (HLB) to meet the requirement of the demulsification. ¹HNMR, ¹³CNMR, and FTIR spectra were utilized to verify their chemical structures. The surface properties and zeta potential were also investigated. Demulsifier dose, separation time, and HLB values were taken into account to evaluate the demulsification efficiency of the synthesized APEI. The results suggested that the prepared demulsifiers had high ability to reduce the surface and interfacial tensions and also broke successfully water-in-Arabian heavy crude oil emulsions. The demulsification efficiency of DNPA-5 reached 100% for crude oil/water emulsion (90/10 vol %).

Synthesis and Surface/Interfacial Properties of Novel Dialkyl Disulfonate Gemini Surfactants Derived from 1,3,5-triazine

A series of novel dialkyl disulfonate Gemini surfactants (Cn-GSBS, n = 8, 12, 14, 16, n is the carbon number of the hydrophobic chain) was synthesized from cyanuric chloride, aliphatic amine, ethylenediamine, N,N'-dimethyl-1,3-propyldiamine and sodium 2-chloroethanesulfonate. The chemical structures of the prepared compounds were confirmed by FT-IR and 1H NMR. The critical micelle concentrations (CMC) in aqueous solutions at 25°C were determined by surface tension method. The CMC value decreased with increasing length of the carbon chain. The CMC reached a minimum as low as 5 × 10−5 mol · L−1 for C16-GSBS. The interfacial tensions (IFT) between Daqing crude oil and Cn-GSBS surfactant solutions were also measured. The effects of the concentration of Na2CO3, the concentration and carbon chain length of Cn-GSBS on the IFT of crude oil-water were investigated in detail. The results show that, for the aqueous surfactant system containing the weak base Na2CO3, oil-water interfacial tension can be reduced to 10−2 mN m−1 orders of magnitude. The results also indicate that with the increase of surfactant concentration and the chain length, the oil-water interfacial tension decreased markedly, which indicates that Cn-GSBS surfactants have a good interface activity. These surfactants are good candidates for weak base-surfactant-polymer EOR process.

Aggregation behaviours and bactericidal activities of novel cationic surfactants functionalized with amides and ether groups

Novel cationic surfactants exhibit high surface activity, interesting aggregation behaviors in aqueous solution and excellent bacterial activity.