A new fluorescent film sensor for Pb(II) ions developed by simulating bio-mineralization process synthesizing of ZnS/CS nanocomposite

Chitosan/zinc sulfide (CS/ZnS) nano-composite films have been prepared by simulating bio-mineralization process. Factors affecting the hydrothermal stability and fluorescence properties of the films have been studied. Furthermore, the sensing properties of nano-composite films to lead ions have been systematically investigated. SEM and TEM observations showed that the size of ZnS particles is 70 nm, and the particles are evenly distributed within the CS films. The fluorescence emission of the nano-composite films indicates that the sizes of real fluorescing ZnS particles are less than 20 nm. This suggests that ZnS particles observed via SEM and TEM may be aggregates of smaller ZnS particles, and the smaller particles may be separated by the organics. The fluorescence emission (363 nm) of the nano-composite films is very sensitive to the presence of Pb ions. C(Pb2+) increased from 0 to 664.2 mg L−1 increases the emission dramatically. The emission is hardly affected by common ions in water, except for the iron ions. The films may be developed as excellent sensing films for Pb ions in water.