Investigation of the Aqueous Dissolution of Galena (PbS) Nanoparticles by HRTEM

Abstract

is one of the most common base metal sulfide minerals in nature. Although galena is insoluble in water, on exposure to acid solution, its solubility can exponentially increase with the proton activity. Hence the dissolution of galena in acid solution can be an important reaction controlling the transport and transformation of Pb in natural waters. Moreover, sulfide nanocrystals have been found in the natural environment as a result of bacterial metabolism [1] or the breakdown of sulfides and silicates [2], which leads to an intense interest in understanding the dissolution mechanism of sulfide nanocrystals. But there are still many unknows about the size-dependent dissolution. Theoretically, it is predicted by the Kelvin equation that the solubility of grains increases exponentially with the decrease of gain size when other parameters are fixed [3]. But recent dissolution studies of hydroxyapatite have revealed that dissolution rates decreased, eventually resulting in effective dissolution suppression, when the grain size fell into a critical length scale, always at the nanoscale [4]. So the investigation of galena nanocrystals is important for studying the special dissolution mechanism of nanocrystals and could also assist environmental remediation.

Size/Shape–Property Relationships of Non‐Carbonaceous Inorganic Nanoparticles and Their Environmental Implications

“…Currently, in our laboratory, the fi rst two factors are being studied. The non -oxidative dissolution of ∼ 15 nm diameter lead(II) sulfi de (PbS) nanoparticles in hydrochloric acid (pH 3) is being examined (Liu et al , 2007a ). Bright -fi eld transmission electron microscopy (TEM) is used to track changes in particle size and high -resolution TEM is used to measure changes in morphology and structure.…”