Phytoremediation of CdS/Te quantum dots by Ocimum basilicum in the presence of EDTA.

Abstract

The use of nanomaterials like quantum dots (QDs) with optical properties has increased in the last decade because of their electronics, medicine, and environmental applications. The lack of recycling and appropriate disposal causes these materials to be considered new emerging contaminants. In this research, the extraction and translocation (phytoextraction) of cadmium as QDs by Ocimum basilicum "basil" in the presence of EDTA (chelating agent) was studied. For edible plants are essential to know where the contaminants are located to minimize human consumption. In this work, the phytoextraction, distribution, and translocation of cadmium (under ionic solution-CdIS and CdS/Te QDs) at 25 and 50mg/kg-soil and in the presence of 1,000mg/kg-soil EDTA was studied in O. basilicum (a commercialized culinary herb) for three and six weeks. Basil seedlings were grown in an environmentally controlled chamber at 24-28o C and 12/12 hours periods of light and darkness. The highest cadmium concentration was found in the roots from where it is translocated to stems and leaves. CdS/Te QDs at low concentration (25mg/kg and 3 weeks of exposure) had the highest translocation factor, indicating that cadmium's nanocrystal (QDs) forms can affect the phytoextraction mechanism. The highest bioconcentration of cadmium was reached at a high contaminant concentration. The bioconcentration factors confirm that O. basilicum phytoextracts cadmium from soils contaminated with CdS/Te QDs and CdIS. The bioconcentration factors of cadmium (under both species CdS/Te QDs and CdIS) increase in the presence of EDTA. The bioconcentration and translocation factors suggest that consuming "basil" from contaminated soils with CdS/Te QDs at low concentrations increases the exposition to this metal.