CO2水基泡沫的稳定机理研究

Study of the stability of the CO_2 aqueous foam

考察了多种表面活性剂溶液生成的二氧化碳水基泡沫的稳定性,发现十二烷基硫酸钠(SDS)稳定二氧化碳泡沫的效果比较突出。以SDS与脂肪醇聚氧乙烯醚硫酸钠(AES)体系对比,采用分子动力学模拟方法研究泡沫体系中二氧化碳分子的增溶、扩散等行为以及泡沫液膜中表面活性剂的界面排布规律,并采用FT-IR探测二氧化碳透过泡沫液膜的透过性。实验结果与模拟结果吻合,表明二氧化碳气体分子可增溶在泡沫液膜上表面活性剂疏水链间,并与水分子有相互作用,可渗透进入泡沫液膜,在泡沫液膜内增溶,因此二氧化碳分子透过液膜的扩散能力强,泡沫聚并破灭速度加快。SDS分子疏水链在泡沫液膜界面层内排列致密,液膜内二氧化碳增溶量小,二氧化碳分子透过SDS泡沫液膜的扩散速度较慢,因此泡沫稳定性好。

The stability of carbon dioxide （CO2 ） water-based foam stablized by surfactants was detected. It was found that sodium dodecyl sulfate （SDS） have apparently better stabilization capacity for the CO2 foam. The molecular array behavior of CO2 and surfactant molecules in foam films was investigated by molecular dynamics simulation. A kind of bipolar-headed surfactant alkyl polyoxyethylene sulfate （AES） having the same alkyl chain and negative charged head group with SDS was investigated as a comparison system, to find out how the microcharacter and array behavior of mol- ecules in the foam films determined by molecular interaction and CO2 effect the foam stability. It was found that the car- bon dioxide could not only distribute in the tail chains of surfactant molecules in gas/water interface, but also have interactions with water molecules distributed near the head groups of surfactants, which resulted in two effects of aspect：one is the increase of the chance that carbon dioxide molecules penetrating through the foam film, which made the carbon dioxide foam instability, and the other is the increase of the hydrophobicity of surfactants, which induced the variation of the array behavior of surfactants. Fourier transform infrared （FT-IR） was used to detect the gas permeability of the foam film. The experimental results showed that the tail chains of SDS arranged closely and the amount of CO2 penetrating through the foam film was little, which was in favor of the nice foam stability. The experimental results agreed very well with the molecular simulation results.