Luminescent polymer composite made of glucose derived carbon dots/polyvinyl alcohol for the sensitive detection of Pb2+ in water

Abstract

The present work emphasizes on the properties of luminescent polymer composites made from glucose derived carbon dots (g-CDs) integrated into polyvinyl alcohol (PVA) matrix by a solution casting method and their application for the trace level detection of Pb2+ in water based on fluorescence quenching. This method offers a convenient approach to explore solid state fluorescence of CDs in a host matrix providing good chemical, thermal and mechanical stability to CDs and envisages on the development of flexible, freestanding and sustainable polymer films as probes for the on-site strip based testing of lead in water. The emission wavelength appeared to be broad covering almost the entire visible spectrum, whereas the g-CDs showed emission only in the green region of the visible spectrum. The photoluminescence (PL) was also unaffected by the change in pH levels in aqueous media providing ample scope for their application in both acidic and basic conditions. The composites are found to be environmentally benign as confirmed from cytotoxicity studies and exhibit fluorescence quenching which correlates with the concentration of Pb2+ ions. The detection limit is as low as 4.71 nM and 0.93 nM respectively for g-CDs and g-CDs/PVA composite, the lowest values reported for sugar derived CDs and its polymer composite. This sustainable probe shows good linearity in the low detection range 0–50 nM and the experimental results confirm a static quenching process for the selective and sensitive detection of Pb2+.