Unravelling Surfactant Partitioning: Part 2 – Experimental Study of Multi-component Surfactant Partitioning Responses and their Influence on Inhibition Performance

In Part 1 of this two-part paper, a predictive model for multi-component partitioning was developed based on knowledge of individual component micellization and partitioning characteristics. In Part 2, the model’s validity is assessed through comparison with experimental partitioning data for an 1 wt.% NaCl brine:toluene system containing mixtures of two benzylammonium chloride corrosion inhibitors (BAC-C12 and BAC-C16). Following model validation, the implications of the experimental partitioning behavior on corrosion inhibition performance are examined via rotating cylinder electrode (RCE) experiments. Through selected experiments, the important role of each of the two surfactants and their relative molar concentration in influencing overall corrosion inhibition performance is examined. While BAC-C12 exhibited poor inhibition in isolation, when combined with BAC-C16 at specific molar ratios, BAC-C12 played a crucial role in retaining the longer chain surfactant in the aqueous phase. This response enabled BAC-C16 (the more effective surfactant corrosion inhibitor) to work synergistically with BAC-C12 to suppress carbon steel corrosion more effectively than the two components alone under these particular conditions.