Effect of organic alkali on interfacial tensions of surfactant solutions against crude oils

- The ultralow IFTs can be reached at optimum conditions for organic alkaline and crude oil interfaces.
- The content and structure of petroleum acid are important factors to control IFTs.
- The increase of molecular size of organic counter ion will result in the increment of IFT.
- The ultralow IFTs can be easily reached by adding petroleum sulfonate to organic alkaline solutions.