Electrochemically Reversible Solubilization of Polycyclic Aromatic Hydrocarbons by Mixed Micelles Composed of Redox-active Cationic Surfactant and Conventional Nonionic Surfactant

Reduplicate utilization of surfactants is a key factor for Surfactant-Enhanced Remediation (SER) technology to reduce its high operation costs. In order to achieve the reuse of surfactants, this study attempted to construct a novel reversible solubilization system for SER. Three typical polycyclic aromatic hydrocarbons (PAHs) pyrene, phenanthrene, and acenaphthene were controllably solubilized and released by the mixed micelles composed of redox-active cationic surfactant (11-Ferrocenylundecyl) trimethylammoniunm bromide (FTMA) and conventional nonionic surfactant Tween80. Solubilization of PAHs is assumed to be controlled by changing the redox states of FTMA. Cyclic voltammograms tests of FTMA showed the oxidation and reduction potential were 0.4570 and 0.4068 V, respectively, and the peak currents ratio of FTMA and FTMA⁺ was 1.26, verified that FTMA possesses electrochemically reversible property. In FTMA-Tween80 mixed solutions, CMC values demonstrated the nonideal interaction between the two surfactants and the interaction parameters (β) was -5.5296 when the mass ratio was FTMA:Tween80 = 2:8. Due to the synergistic solubilization effect, the apparent water solubilities of PAHs were significantly enhanced by the mixed surfactant, and they were much higher than those in single surfactant. After oxidation, more than 50% of the PAHs in mixed micelles could be released, the cumulative release efficiency of selected PAHs followed the order of pyrene > pherantherene > acenaphthene. Briefly, such results in this article provide a facile method to meliorate the SER technology.