论文部分内容阅读
通过测定全氟辛酸铵(APFO)、全氟辛酸三甲铵(TMHPFO)、全氟辛酸三乙铵(TEHPFO)在不同浓度NaCl(0.1,0.3,0.5 mol?L-1)存在时水溶液的表面张力曲线,考察不同反离子的氟表面活性剂其表面活性随无机盐浓度的变化.结果表明,NaCl对APFO的胶束化有明显的促进作用;对于TMHPFO和TEHPFO则在NaCl浓度较低时有很小的促进作用,NaCl浓度较高时由于Na+和N(CH3)+3(或N(CH2CH3)+3)之间的离子交换作用反而临界胶束浓度(cmc)增大.APFO,TMHPFO的最低表面张力(γcmc)随着NaCl浓度的增大而增大.而对于TEHPFO,少量NaCl的加入有利于降低γcmc、然后随着NaCl浓度的增大TEHPFO的γcmc增大.这说明,加盐溶液中始终存在着屏蔽效应和离子交换作用的竞争,随着NaCl浓度增大离子交换趋势增大;对于疏水性较高的三乙铵离子在NaCl存在的情况下离子交换作用导致的γcmc升高需要更高的NaCl浓度才能显现.通常认为外加无机盐是增强表面活性剂的表面活性的方法之一,本工作表明,对于有些反离子为有机阳离子的氟表面活性剂,外加无机盐,如NaCl,不仅不能起到显著的增效作用,浓度大时甚至会降低表面活性剂的效能.所以这类表面活性剂在实际使用时应尽量避免高盐环境.
The surface tension curves of aqueous solutions of ammonium perfluorooctanoate (APFO), tetrabutylammonium perfluorooctanoate (TMHPFO) and tetraethylammonium perfluorooctanoate (TEHPFO) in the presence of different concentrations of NaCl (0.1, 0.3 and 0.5 mol·L- The results showed that NaCl promoted the micellarization of APFO significantly, while TMHPFO and TEHPFO had little effect on the concentration of NaCl. NaCl At higher concentrations, the critical micelle concentration (cmc) increases due to ion exchange between Na + and N (CH3) +3 (or N (CH2CH3) +3) The lowest surface tension (γcmc) of APFO, TMHPFO With the increase of NaCl concentration.While adding a small amount of NaCl for TEHPFO is helpful to reduce γcmc, then the γcmc of TEHPFO increases with the increase of NaCl concentration.This shows that there is always a shielding effect in salt solution and Ion exchange, the ion exchange tended to increase with the increase of NaCl concentration. For higher hydrophobicity of triethylammonium ion, higher concentration of γcmc caused by ion exchange in the presence of NaCl required higher NaCl concentration to appear It is generally assumed that the added salt is increased Surfactant surface activity of this method, the work shows that some of the counter-ions for the organic cationic fluorosurfactants, plus inorganic salts, such as NaCl, not only can not play a significant synergistic effect, even at high concentrations Reduce the effectiveness of the surfactant.Therefore, such surfactants should be avoided in actual use in high salt environment.