摘要：

电导率滴定法具有自动化程度高、数据准确、操作便捷等优点。基于十六烷基三甲基溴化铵（CTAB）和油田三元复合驱用阴离子表面活性剂〔十二烷基苯磺酸钠（SDBS）、重烷基苯磺酸钠（SAS）和石油磺酸钠（PAS）〕反应生成聚电解质复合物的原理，利用CTAB滴定阴离子磺酸盐，根据水溶液电导率发生突变的点确定滴定终点，进而计算SDBS、SAS和PAS的质量分数。电导率滴定法对油田常用的3种阴离子表面活性剂的质量分数检测结果重复性较好，标准差均小于0.30。考察了影响电导率滴定稳定性的因素，建议实验温度控制在25 ℃，分子结构为链状的阳离子滴定剂对滴定准确性影响较小，溶液中低浓度的NaCl、KCl、MgCl₂和CaCl₂对滴定结果影响较小，但会造成反应后溶液电导率升高。电导率滴定法与两相滴定法检测结果的平均误差在1.0%以内，且检测成本仅为重量法的25%，具有明显优势。

关键词: 电导率滴定法, 阴离子磺酸盐, 聚电解质复合物

Abstract:

Conductivity titration has the advantages of high automation, accurate data, and convenient operation. Based on the principle that cetyl-trimethyl ammonium bromide(CTAB) reacted with anionic surfactants used in ASP flooding to form polyelectrolyte complex, including sodium dodecylbenzene sulfonate(SDBS), sodium alkylbenzene sulfonate(SAS), and sodium petroleum sulfonate(PAS), CTAB was used to titrate anionic sulfonates. The titration endpoint was determined by identifying the rapid change in the conductivity of the aqueous solution, thereby the mass fractions of SDBS, SAS, and PAS could be calculated. The method had good repeatability for detecting the mass fractions of anionic surfactants used in ASP flooding, and the standard deviation of the surfactant was less than 0.30. Factors affecting the stability of conductivity titration were investigated. It was recommended to control the experimental temperature as 25 ℃. Cationic titrants with linear molecular structures had minimal impact on titration accuracy. Low concentrations of NaCl, KCl, MgCl₂, and CaCl₂ in the solution had little influence on the titration results but increased post-reaction solution conductivity. Compared to the two-phase titration method, the average error of conductivity titration was within 1.0%, and its detection cost was only 25% of that of gravimetric analysis, which had significant advantages.

Key words: conductivity titration, anionic sulfonate, polyelecrolyte complex

中图分类号: 

• X741

• TQ423