表面活性剂对海藻酸钠稀水溶液剪切粘度的影响

通过粘度法考察了不同pH值时, 阴离子聚电解质海藻酸钠(NaAlg)与阴离子表面活性剂十二烷基硫酸钠(SDS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、非离子表面活性剂辛基酚聚氧乙烯醚(TritonX-100)以及它们的复配体系的相互作用. 研究表明, 在酸性条件下, SDS和TritonX-100与NaAlg之间主要是疏水作用, 随着表面活性剂浓度的增加, 体系粘度下降直到基本不变, CTAB与NaAlg主要发生静电作用和疏水作用, 体系粘度随CTAB浓度的增加呈现先上升后下降的趋势. 在实验条件下, TritonX-100浓度为0.05 mmol·L-1时, SDS的加入, 使得NaAlg/TritonX-100体系的零剪切粘度下降, 而CTAB的加入, 在pH=3.0和5.0时, NaAlg/TritonX-100体系的零剪切粘度出现上升, 在pH=6.4时, 该体系零剪切粘度下降.

Effect of Surfactants on the Shear Viscosity of Dilute Aqueous Solutions of Sodium Alginate

Interactions between the anionic polyelectrolyte sodium alginate (NaAlg) and the anionic surfactant sodium dodecyl sulfate (SDS), the cationic surfactant cetyltrimethylammoniumbromide (CTAB), non-ionic surfactants octylphenol polyethoxylates (TritonX-100) as well as their compounded system were investigated by viscosity measurement techniques at different pH values in dilute solution. A hydrophobic interaction was observed in NaAlg/SDS and NaAlg/TritonX-100 aqueous solutions. By increasing the surfactant concentration the zero-shear viscosity initially decreased and then remained almost unchanged. However, the strong association between NaAlg and CTAB was affected by an electrostatic attraction and also a hydrophobic interaction. In acidic solution, the zero-shear viscosity initially increased and then decreased as the CTAB concentration increased. At a TritonX-100 concentration of 0.05 mmol·L-1, the zero-shear viscosity decreased upon addition of SDS for the NaAlg/TritonX-100 system under laboratory conditions. Upon addition of CTAB, the zero shear viscosity of NaAlg/TritonX-100 system increased at pH 3.0 and 5.0 but decreased at pH 6.4.