阳离子表面活性剂十六烷基三甲基溴化铵对酞酸酯类化合物增溶性研究

STUDY ON WATER SOLUBILITY ENHANCEMENTOF PHTHALIC ESTERS BY A CATIONIC SURFACTANT (CTAB)

用阳离子表面活性剂十六烷基三甲基溴化铵对六种酞酸酯类化合物(五种脂肪链酞酸酯和一种苯基酞酸酯)进行了增溶性实验．结果表明,在表观浓度(Ｃｓ)小于临界胶速浓度(ＣＭＣ)时,十六烷基三甲基溴化铵对四种酞酸酯(ＤＭＰ和ＤＰｈＰ除外)有一定程度的增溶作用;当Ｃｓ大于ＣＭＣ时,对六种化合物的增溶性显著增强．其增溶性(Ｓｔ/Ｓｗ)随Ｃｓ增大而线性递增:当Ｃｓ＜ＣＭＣ时,Ｓｔ/Ｓｗ＝ａ＋Ｋｍｎ·Ｃｓ,ｒ＞０．９０,ｎ＝５;当Ｃｓ＞ＣＭＣ时,Ｓｔ/Ｓｗ＝ａ＋Ｋｍｃ·Ｃｓ,ｒ＞０．９９,ｎ＝５． 各化合物增溶系数随各自固有水溶性(Ｓｗ)减小而增大(苯基酞酸酯有所反常),ｌｇＫｍｎ和ｌｇＫｍｃ与各自ｌｇｌ/Ｓｗ具有良好的线性正相关性．本文进一步对增溶机理进行了分析解释．

Water solubility enhancements of six phthalic esters (5 aliphatic phthalates and one phenyl ph-thalate) by a cationic surfactant, cetyltrimethylammonium bromide (CTAB), have been studied at 25℃. While the solubilities of the 6 phthalates are significantly enhanced by the surfactant at con-centration above the critical micelle concentration (CMC), the surfactant at concentration below CMC also exhibits a degree of solubility enhancements on 4 phthalates. The solubility enhancements (St/Sw) of these phthalates are proportional to the observed concentration of the surfactant ( Cs) . When Cs> CMC, St/Sw = a + Kmc·Cs, with > 0.99, n = 5; when Cs < CMC, St/SW = a + Kmn ·Cs, with r > 0.90, n = 5. lg Kmn and lg Kmc of these phthalates correlate linearly with their respective lg 1/Sw, with phenyl phthalate aberrant a lot. Based on these data, the mecha-nism for the solubillity enhancement is provided.