ZnS nanorod as an efficient heavy metal ion extractor from water

It is an important goal for material scientists to establish a method of capturing contaminant metal ions in water with high efficiency and then to separate them out with ease. Nanomaterials with carefully chosen structure can be a useful tool in this regard. Here we use wurtzite ZnS nanorods having open ends with only sulphur atoms, and therefore negatively polarized, which consequently catalyze adsorption of various cations on them. However, based on the ionic radius and oxidation state of the contaminant ion, such large scale adsorption initiates decomposition of the original nanostructure, followed by growth of new phases. This growth process leads to the formation of large grain solids which makes it easier to remove the contaminant ions from water by simple filtration techniques; in every case, a nearly ten times larger amount of the contaminant ion is removed for every mole of consumed ZnS. This important catalytic role of the polar nanosurface could therefore be exploited to develop an efficient method of water purification.