Simultaneous elution of polycyclic aromatic hydrocarbons and heavy metals from contaminated soil by two amino acids derived from β-cyclodextrins

Abstract

Two highly water-soluble amino acids, which derived from β-CDs, i.e., glutamic acid-β-cyclodextrin (GluCD) and ethylene-diamine-β-cyclodextrin (EDCD), were synthesized and were examined for their effect on solubilization of anthracene (ANT), complexation of cadmium (Cd 2+), and elution removal of ANT and Cd 2+ in soil. The results showed that GluCD and EDCD were powerful complexant for ANT and Cd 2+. In the presence of 10 g/L GluCD and EDCD, the solubilization of ANT increased by 47.04 and 23.85 times compared to the control, respectively. GluCD resulted in approximately 90% complexation of Cd 2+ while 70% complexation was observed for EDCD. Simultaneously, GluCD and EDCD could greatly enhance the elution removal of ANT and Cd 2+ from soil. GluCD resulted in the highest elution efficiency of ANT and Cd 2+. With the addition of 10 g/L GluCD, 53.5% of ANT and 85.6% of Cd 2+ were eluted, respectively. The ANT had a negligible effect on the Cd 2+ removal due to different complexing sites of ANT and Cd 2+, while Cd 2+ enhanced the ANT removal under the addition of GluCD because Cd 2+ neutralized the –COOH group of GluCD. Adversely, the removal of ANT was decreased with Cd 2+ under the addition of EDCD, this was due to the fact that Cd 2+ enhanced the polarity of EDCD molecule and inhibited the complexation between ANT and EDCD. The study suggested that GluCD could be preferred and be successfully applied to remediation of heavy metals or organic compounds in contaminated soil.