tellurium and aluminum-sulfate

Commercial use of quantum dots (GDs) will lead to their entry into aquatic environments. This study examines the characteristics and stability of CdTe QDs with thioglycolate capping ligands in water as well as their removal by alum salts. The capping ligands of QDs are a key factor in determining their fate in water. Protonated thioglycolate capping ligands cause QDs to aggregate. The stability of QDs depends more on their ionic composition in water than on the ionic strength. In KCl solution, QDs remain stable even under 0.15 M ionic strength. Relatively low concentrations (< or = 2 meq/L) of divalent (Mg2+ and Ca2+) or trivalent (Al3+) cations, however, can induce aggregation. The proposed mechanism for this phenomenon is that multivalent metal cations (or their hydrated species) react with capping ligands to form complexes that bridge QDs or neutralize their surface charges. Because the complexation of hydrated Al3+ with capping ligands inhibits the formation of Al(OH)3 precipitates, alum dosages higher than the A3+ solubility are required to form settleable flocs and remove QDs from nanopure water by sedimentation. Divalent cations (Mg2+ and Ca2+) in tap water induce the formation of settleable QD flocs such that 70-80% of the QGDs by mass settle out.

Topics: Alum Compounds; Cadmium Compounds; Calcium; Flocculation; Hydrogen-Ion Concentration; Ligands; Osmolar Concentration; Particle Size; Quantum Dots; Solubility; Tellurium; Thioglycolates; Water; Water Pollutants, Chemical; Water Purification

The capability of some metal compounds for inducing micronuclei (MN) in human lymphocytes was studied. In this investigation, Al (III), Cd (II), Hg (II), Sb (V), Te (VI), and Tl (I) salts were considered. The FISH (fluorescence in situ hybridization) technique with a centromeric probe was coupled with the MN assay in binucleated cells in order to detect both centromere-positive MN (C+ MN) due to malsegregation phenomena and centromere-negative MN (C- MN) due to chromosome breakage. The blood of two young nonsmoking male donors was employed for all experiments. In both donors, all the tested metal compounds, with the exception of Tl(2)SO(4), showed a statistically significant increase of MN compared to controls, at least at one dose. FISH analysis revealed an increase in the fraction of C+ MN for Al, Cd, and Hg compounds, and of C- MN for the Sb salt; however, this was not a statistically significant increase. A different efficiency was observed for the different metal compounds, in particular, KSbO(3) and CH(3)HgCl, which were highly genotoxic, whereas the others showed minimal effects.

Topics: Alum Compounds; Antimony; Cadmium Chloride; Centromere; Cytochalasin B; Dose-Response Relationship, Drug; Humans; In Situ Hybridization, Fluorescence; Lymphocytes; Male; Mercuric Chloride; Metals; Micronucleus Tests; Mutagens; Salts; Tellurium; Thallium