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Solubility enhancement of phenanthrene using novel chelating surfactant

A novel chelating surfactant denoted as sodium N-lauroyl ethylenediamine triacetate (N-LED3A) with both surface activity and chelation functions was studied for phenanthrene (PHE) solubilisation ability. The critical micelle concentration (CMC) of N-LED3A was measured, and the effects of the initial N-LED3A concentration, temperature, pH value and coexisting ions (Na+, Ca2+ and Cu2+) on PHE solubilisation by N-LED3A were investigated. The results demonstrated that PHE solubility was efficiently enhanced by N-LED3A, especially with N-LED3A concentrations above the CMC, which was 707 mg L−1 when measured at 25°C. The temperature influenced the apparent PHE solubility slightly and the apparent solubility of PHE was significantly affected by the pH. Na and Ca were shown to increase the PHE solubility, while Ca exhibited a better promoting ability than Na+. A suitable quantity of Cu could significantly enhance the solubilisation capacities of N-LED3A at pH 5. The mechanism of the interaction between Cu+ and N-LED3A was further confirmed by Fourier transform infrared spectroscopy (FTIR). These results reveal that Cu2+ can be chelated with N-LED3A to form a chelate complex. The results implied that N-LED3A had the potential to remediate soils contaminated by both organics and heavy metals.