Preparation of stable colloidal solution of cadmium sulfide CdS using ethylenediaminetetraacetic acid

By the method of chemical condensation a stable aqueous colloidal solution of nanoparticles of cadmium sulfide was obtained. The solution obtained in the daylight had a bright lemon-yellow color. For the temporary stabilization of the solution was used an organic complexone, disodium ethylenediaminetetraacetate (EDTA), that prevented coagulation of colloidal particles up to several months at 4°C. At room temperature, the solution remained stable during a month. The structure and properties of the disperse phase were studied by the X-ray diffraction, optical fluorescence, and electron microscopy. The solid particles size is about 3 nm, they have a disordered close-packed structure with the space group P6mm and possess the photoluminescence color from green to orange depending on the duration of keeping the solution. The size of coagulates was 10 nm, 100 nm, and 1 μm after keeping for 1, 2, and 4 months, respectively.