An Investigation on Heavy Metals Bio-Sorption by Azolla filiculoides in the International Anzali Wetland

Abstract

The ultrasound assisted emulsification microextraction (USAEME) method followed by<br />inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used for preconcentration and<br />determination of bismuth (Bi), indium (In) and lead (Pb) in the plant Azolla filiculoides Lam. Calix [4] pyrrole was used as a chelating agent and tetrachloroethylene was selected as extraction solvent. The main parameters of the USAEME method were optimized by using response surface methodology (RSM). The optimal conditions were as follows: 130 μL for volume of extraction solvent, 4 min for sonication time, 6.75 (w/v %) for salt concentration, 890 mg/L for concentration of chelating agent and 7.5 for pH. The calibration graphs were linear in the range of 1-1500 μg/L for Bi and In, and 1-1000 μg/L for Pb with the determination coefficients (R2) of 0.9983, 0.9974 and 0.9997, respectively. The limits of detection (LODs) for Bi, In and Pb were 0.57, 0.76 and 0.84 μg/L, respectively. Under the optimal conditions, the method was successfully applied to the determination of Bi, In and Pb in Azolla filiculoides Lam. tissues in Anzali wetland and satisfactory relative recoveries (94–97%) were achieved.