Colloidal and Immobilized Nanoparticles of Lead Xanthates

Although nanoparticles of heavy metal xanthates and their hydrosols can play important roles in froth flotation, environmental issues, analytics, and manufacturing of metal sulfide nanocomposites, they have received little attention. We studied colloidal solutions and immobilized particles prepared via interaction of aqueous lead nitrate with alkyl xanthates applying UV-vis absorption spectroscopy, dynamic light scattering, zeta potential measurement, thermogravimetry analysis, Fourier transform infrared spectroscopy, Raman scattering, X-ray photoelectron spectroscopy, atomic force microscopy, and transmission electron microscopy. The hydrodynamic diameter of colloidal particles of Pb(SSCOR)₂ decreased from 500 to 50 nm with an increase in the alkyl radical length and the initial xanthate to lead ratio (X/Pb); the zeta potential magnitude varied similarly, although it remained negative. The effect of pH in the range of 4.5-11 was minor, but the colloids produced using excess of Pb²⁺ in alkaline media were close to PbX and decomposed much easier than PbX₂. The uptake of lead xanthates on supports was generally low because of negative charges of the colloids; however, 50-100 nm thick PbX₂ films were deposited on PbS and SiO₂ from the media of X/Pb < 2 and pH < 9 because of preadsorption of Pb²⁺, while nanorods formed on highly oriented pyrolytic graphite.