溴化十二烷基吡啶的吸附和表面胶团化对二氧化硅悬浮液稳定性的影响

研究了阳离子表面活性剂溴化十二烷基吡啶（ＤＰＢ）的吸附和表面胶团化对二氧化硅（ＣＡＢ－Ｏ－ＳＩＬ）悬浮液稳定性的影响，以及加入电解质的效应．结果表明：ＤＰＢ在ＣＡＢ－Ｏ－ＳＩＬ上的吸附等温线呈双平台（或ＬＳ）型，溴化钠（０．１ｍｏｌ／Ｌ）的存在使吸附等温线向低浓区移动，第二平台的饱和吸附量增大，但基本不影响第一平台的吸附量，这些结果都与涉及形成表面胶团的二步吸附模型相符．当ＤＰＢ浓度很低时，ＣＡＢ－Ｏ－ＳＩＬ悬浮液的稳定性随ＤＰＢ浓度的增大而下降；当ＤＰＢ浓度增至ｓｍｃ（临界表面胶团浓度）附近时，悬浮液稳定性急剧提高．ＮａＢｒ的存在，并不影响上述悬浮液稳定性规律．利用表面活性剂的二步吸附和颗粒相互作用模型，并结合ＤＰＢ吸附等温线的研究结果，可以合理地解释ＣＡＢ－Ｏ－ＳＩＬ悬浮液稳定性的实验结果．

Effects of Adsorption and Surface Micellization of Dodecylpyridinium Bromide on the Stability of Silica Suspension

The effects of the adsorption and surface micellization of dodecylpyridinium bromide(DPB) on the stability of silica(CAB O SIL) suspension have been investigated. The adsorption isotherms of DPB on a flame hydrolyzed silica from aqueous solution exhibit two plateau(i.e.LS type isotherm). In the presence of 0 1 mol/L NaBr the adsorption isotherm of DPB is displaced to lower equilibrium concentration region and the limiting adsorption is enhanced, but the adsorption in the first plateau remains nearly constant. In the low concentration range of DPB, the stability of silica suspension decreases with increasing concentration of DPB. However, near smc (surface micelle concentration) of DPB the stability increases sharply with increasing concentration of DPB. In the presence of NaBr, the stability of silica suspension is much lower in comparison with that without addcd salt. The results are explained in terms of the surface micellization model and the adsorption isotherms of DPB.