FEL Division, Jefferson Laboratory and Department of Applied Science, The College of William and Mary, Newport News, VA 23606, USA.
J Colloid Interface Sci. 2010 Feb 15;342(2):474-8. doi: 10.1016/j.jcis.2009.10.031. Epub 2009 Oct 20.
Analysis of DRIFTS spectra was used for a quantitative study of competitive adsorption of myristic and salicylic acids onto kaolinite or gamma-alumina. Peaks unique to the ring or the chain were selected and single molecule studies used as calibration. Samples were exposed to hexane solution containing equal molecular quantities of each acid. The surface loading of salicylic acid was not influenced by the presence of myristic acid on either mineral but the maximum loading of myristic acid was decreased (46-50%) by salicylic acid. Displacement of myristic acid from gamma-alumina, but not kaolinite, was observed when excess salicylic acid remained in solution. A 25% increase in the maximum loading was observed for kaolinite, but not for gamma-alumina. On gamma-alumina, after a loading of 1molecule per nm(2), increased exposure resulted in salicylic acid adsorption only, this value is approximately the same for salicylic acid adsorption from aqueous solution or for water washed hexane treated samples [1,2]. Thus a set of sites for adsorption of either acid is indicated together with other energetically less favorable sites, which can be occupied by salicylic, but not by myristic, acid.
采用 DRIFTS 光谱分析对豆蔻酸和水杨酸在高岭土或γ-氧化铝上的竞争吸附进行定量研究。选择了独特的环峰或链峰，并将单分子研究用作校准。将样品暴露于含有等量每种酸的正己烷溶液中。在这两种矿物上，水杨酸的表面负载不受豆蔻酸存在的影响，但水杨酸会降低豆蔻酸的最大负载（46-50%）。当溶液中仍有过量的水杨酸时，观察到从γ-氧化铝上取代豆蔻酸，但不从高岭土上取代。对于高岭土，最大负载增加了 25%，但对于γ-氧化铝则没有。在γ-氧化铝上，当每 nm² 负载 1 个分子时，增加暴露量只会导致水杨酸吸附，该值与从水溶液或经水洗正己烷处理的样品中吸附水杨酸的值大致相同[1,2]。因此，表明存在一组可用于吸附两种酸的位点，以及其他能量上不利的位点，这些位点可以被水杨酸占据，但不能被豆蔻酸占据。
