Application of stabilized zero valent iron nanoparticles for immobilization of lead in three contrasting spiked soils

Abstract

This study was conducted to synthesize and characterize the ZVINs stabilized with acid ascorbic (AAS-ZVINs) and to assess their ability to immobilize Pb2+ in sandy, acidity and calcareous spiked soils. To determine the availability of Pb2+, the DTPA-extractable Pb in three spiked soils was studied in an experiment of a completely randomized design with a factorial arrangement of treatments consisting of the AAS-ZVIN dosage, Pb2+ contamination levels and contact times (aging). The distribution of the chemical forms of Pb was also determined using the sequential extraction method. The SEM and XRD analyses indicated that AAS-ZVINs had the mean size of less than 50 nm and the maximum 2θ peak at 44.8°, respectively, demonstrating the nano-sizes and zero valence of the iron particles. The results indicated that the DTPA-extractable Pb in three spiked soils decreased significantly with increasing the AAS-ZVIN dose at the contamination levels of 50 and 150 mg kg−1. The acidic soil displayed the greatest DTPA extractable Pb reduction cmopared with the other two soils. Continuous reduction of the DTPA extractable Pb in all three spiked soils was observed as the contact time (aging) reached 4 weeks. Sequential extraction procedures showed a significant decrease of soluble, exchangeable and carbonate-bound Pb fractions and a pronounced increase of organic matter-bound, Fe/Mn oxides-bound and residual Pb fraction after the soils were treated with AAS-ZVINs. The results obtained in the present study suggest that the use of AAS-ZVIN to remediate soils polluted with Pb could be a promising in situ strategy.