不同添加剂对阴离子表面活性剂与多价阳离子沉淀行为的影响

Effect of different additives on the precipitating behavior of anionic surfactant and multivalent cation

用透光率法研究了不同添加剂对阴离子表面活性剂(SDBS)与多价阳离子(Ca2+)在不同条件下沉淀行为的影响,研究结果表明,在溶液中加入NaCl增大其盐度,加入NaOH、NaHCO3提高其pH值,加入多价金属离子螯合剂(EDTA)或表面活性剂复配,均对SDBS与Ca2+的沉淀有抑制作用,但SDBS与Ca2+的沉淀行为随着体系条件的不同而不同。比较几种方法抑制沉淀的效果,认为加入EDTA的方法比增加体系盐度或增大体系pH值要好,而表面活性剂(阴离子表面活性剂SDBS与非离子表面活性剂TX-100)复配后,混合体系抗Ca2+的能力更强,即使混合表面活性剂中非离子表面活性剂含量很少(实验中阴离子、非离子表面活性剂摩尔比例为10:1)。溶液中就几乎没有沉淀生成,表明非离子表面活性剂对阴离子表面活性剂钙盐沉淀的抑制作用比NaCl、NaOH、NaHCO3和EDTA强,且这种抗Ca2+的能力随着混合表面活性剂中非离子表面活性剂含量的增加而增强。

The precipitating behaviors of anionic surfactant and mul tivalent cation at different conditions were studied by means of light transmission measurement. The results show that by adding differentadditives, anionic surfactant and multivalent cation displayed different precipitating behaviors. When the concentration of Ca2+ was 1.0 × 10-3 mol/L, less amount of precipitate formed as the increase of NaCl concentration, and when the NaCl concentration was 0.1 mol/ L, no precipitate existed. The precipitating behaviors of anionic surfactant and multivalent ion also changed with the change of pH. If EDTA was added, less surfactant precipitate was formed because of the chelation between EDTA and Ca2+. When the EDTA concentration was 0.01 mol/L, no precipitate existed, suggesting that adding nonionic surfactant TX-100 could inhibit the formation of surfactant precipitate. When the molar content of nonionic surfactant was 10%, there was almost no precipitate.