Theoretical Investigation of the Adsorption of Cadmium Iodide from Water Using Polyaniline Polymer Filled with TiO2 and ZnO Nanoparticles

The removal of heavy metals from drinking water has attracted great interest in water purification technology. In this study, a biocompatible Polyaniline (PANI) polymer filled with TiO2 and ZnO nanoparticles (NPs) is considered as an adsorbent of cadmium iodide from water. Theoretical investigation of the van der Waals (vdW) interactions deduced from the Hamaker constant calculated on the basis of Lifshitz theory was presented. It was found that the surface energy as well as the work of adhesion between water and PANI/NPs across air increases with an increasing volume fraction of the TiO2 and ZnO nanoparticles. Consequently, an increase in the Laplace pressure around the cavities/porosities was found, which leads to the enhancement of the specific contact surface between water and PANI/NPs. On the other hand, for the interactions between CdI2 particles and PANI/NPs surface across water, we show that the interactions are governed principally by the attractive London dispersion forces. The vdW energy and force increase proportionally with the augmentation of the volume fraction of nanoparticles and of the radius of the CdI2 particle. Particularly, the PANI/TiO2 has been proved to be a better candidate for adsorption of cadmium iodide from water than PANI/ZnO.

Study of Structure and Composition of Lead Sulfide Nanostructured Films Doped by Cadmium and Iodine Ions

Lead sulfide films doped with cadmium and iodine ions were obtained by chemical bath deposition from the reaction mixture with thiourea that have thickness of up to 300 nm. An increase in cadmium iodide in the reactor from 5∙10-5 to 5∙10-3 mol/l is accompanied by a decrease in the period of the B1 cubic crystal lattice (space group ) from 0.59368 to 0.59355 nm, due to the replacement of Pb2+ ions in the PbS crystal lattice by a smaller size of ion Cd2+. The cadmium content in the synthesized layers varied from 0.4 to 2.8 at.% with a constant iodine concentration of 1.7–1.9 at.%. An electron microscopic study of the structure showed a decrease in the average crystallite size from 260 nm to 80 nm.