Quaternary Ammonium Salt Surfactant Research Articles

Synthesis, Characterization and Surface‐Activity of a Polyoxyethylene Ether Trimeric Quaternary Ammonium Surfactant

AbstractA trimeric quaternary ammonium salt surfactant containing polyoxyethylene chains was synthesized from fatty alcohol polyoxyethylene ether, pentamethyldiethylenetriamine and thionyl chloride by a two‐step process. Its chemical structure was characterized, and the surface activity in aqueous solution was studied at different temperatures. The results showed that when the concentration attains the CMC (1.0 mmol/L), the surface tension is 38.9 mN m−1 and the conductivity is 105.3μS cm−1 at 25 °C. These show that the trimeric quaternary ammonium salt surfactant containing polyoxyethylene chains exhibits high surface activity and effectively reduces the surface tension of water.

Synthesis and Size Control of Cobalt Phosphate Rosettes Using Surfactant-Templated Synthesis

Novel cobalt phosphate rosettes have been synthesized. Control over the particle size and rosette geometry is afforded through the use of cationic quaternary ammonium salt surfactants. Small variations in the surfactant concentration allow for control over the rosette diameter.

Comparative studies on flotation of illite, pyrophyllite and kaolinite with Gemini and conventional cationic surfactants

To search a novel class of effective silicate mineral collectors, the Gemini quaternary ammonium salt surfactant (butane- α, ω-bis(dimethyl dodeculammonium bromide), 12-4-12) and its corresponding conventional monomeric surfactant (dedecyl trimethyl ammonium bromide, DTAB) were adopted to comparatively study the flotation behaviors of illite, pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6, the best recoveries of illite, pyrophyllite and kaolinite with 3.5×10 −4 mol/L 12-4-12 are 99.2%, 91.7% and 99.6%, respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.

Comparing Effectiveness of Rhamnolipid Biosurfactant with a Quaternary Ammonium Salt Surfactant for Hydrate Anti-Agglomeration

Natural gas is projected to be the premium fuel of the 21st century because of availability, as well as economical and environmental considerations. Natural gas is coproduced with water from the subsurface forming gas hydrates. Hydrate formation may result in shutdown of onshore and offshore operations. Industry practice has been usage of alcohols--which have undesirable environmental impacts--to affect bulk-phase properties and inhibit hydrate formation. An alternative to alcohols is changing the surface properties through usage of polymers and surfactants, effective at 0.5-3 wt % of coproduced water. One group of low-dosage hydrate inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are anti-agglomerants, which prevent agglomeration of small hydrate crystallites. Despite great potential, reported work on hydrate anti-agglomeration is very limited. In this paper, our focus is on the use of two vastly different surfactants as anti-agglomerants. We use a model oil, water, and tetrahydrofuran as a hydrate-forming species. We examine the effectiveness of a quaternary ammonium salt (i.e., quat). Visual observation measurements show that a small concentration of the quat (0.01%) can prevent agglomeration. However, a quat is not a green chemical and therefore may be undesirable. We show that a rhamnolipid biosurfactant can be effective to a concentration of 0.05 wt %. One difference between the two surfactants is the stability of the water-in-oil emulsions created. The biosurfactant forms a less stable emulsion, which makes it very desirable for hydrate application.

Direct alkylation of carboxylic in aqueous samples

Carboxylic acids can be converted to their methyl esters in an aqueous sample which contains no organic solvent. The reaction appears to be assisted by the presence of a quaternary ammonium salt surfactant. The procedure is best described as a pseudo-organic phase, or micelle-like, reaction. The important experimental variables have been optimized by Simplex procedures. The reaction proceeds in 80–100% yield, for common carboxylic acids, at room temperature in less than one hour. This reaction is superior to existing two-phase extractive alkylation procedures.