Aspartic Acid--Cyclodextrin-Assisted Phytoremediation of Soil Cocontaminated with Cadmium and Fluorene Using Alfalfa (Medicago sativa L.)

Phytoremediation may be used for remediation of cocontaminated soil with heavy metals and polycyclic aromatic hydrocarbons (PAHs). However, the low bioavailability of heavy metals and PAHs in soils may have adverse effects on the efficiency of phytoremediation; it is necessary to find an effective method for simultaneously improving bioavailability of PAHs and heavy metals in cocontaminated soils. In this study, a novel aspartic acid--cyclodextrin (ACD) was synthesized, the structural characteristics of ACD were confirmed by FT-IR spectroscopy, and the complexation of fluorene (Flu) and cadmium (Cd) with ACD was studied. Pot culture experiments were conducted to investigate effects of ACD on phytoremediation of soil cocontaminated with Flu and Cd. Results showed that ACD could enhance uptake of Flu and Cd in alfalfa (Medicago sativa L.), and removal percentages of Flu and Cd in planted soil with ACD increased from 45.78% and 25.62% to 66.96% and 34.88%, respectively. Biological activity of planted soils with ACD was obviously higher than that of planted soils without ACD, which resulted in improvement of phytoremediation efficiency. As a promising remediation strategy, ACD-assisted phytoremediation may be a feasible technology for simultaneous removal of PAHs and heavy metals in cocontaminated soils.