tellurium and (3-mercaptopropyl)trimethoxysilane

In this article, mercapto-functionalized helical mesoporous silica nanorods have been synthesized by a one-step co-condensation of tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTS) using cetyltrimethylammonium bromide (CTAB) as a template. Process parameters, including MPTS concentration, stirring time and added volume of ethanol as co-solvent, were both carefully and accurately regulated, and obtained results showed that these parameters all had large effects on the morphology and structure of products. Furthermore, the helical mesoporous silica nanorods were successfully employed as multipurpose carriers for Au nanoparticles (NPs) and CdTe nanocrystals (NCs) by in situ formation and post-loading, respectively. In a preliminary catalytic test, Au NPs as small as ca. 0.6 nm in the helical mesoporous silica nanorods after calcination showed much enhanced catalytic activity for reduction of methylene blue (MB(+)).

Topics: Cadmium Compounds; Gold; Magnetite Nanoparticles; Methylene Blue; Microscopy, Electron, Scanning; Nanotubes; Organosilicon Compounds; Oxidation-Reduction; Porosity; Silanes; Silicon Dioxide; Tellurium

A new method was developed for the speciation of inorganic tellurium species in seawater by inductively coupled plasma-MS (ICP-MS) following selective magnetic SPE (MSPE) separation. Within the pH range of 2-9, tellurite (Te(IV)) could be quantitatively adsorbed on gamma-mercaptopropyltrimethoxysilane (gamma-MPTMS) modified silica-coated magnetic nanoparticles (MNPs), while the tellurate (Te(VI)) was not retained and remained in solution. Without filtration or centrifugation, these tellurite-loaded MNPs could be separated easily from the aqueous solution by simply applying external magnetic field. The Te(IV) adsorbed on the MNPs could be recovered quantitatively using a solution containing 2 mol/L HCl and 0.03 mol/L K2Cr2O7. Te(VI) was reduced to Te(IV) by L-cysteine prior to the determination of total tellurium, and its assay was based on subtracting Te(IV) from total tellurium. The parameters affecting the separation were investigated systematically and the optimal separation conditions were established. Under the optimal conditions, the LOD obtained for Te(IV) was 0.079 ng/L, while the precision was 7.0% (C = 10 ng/L, n = 7). The proposed method was successfully applied to the speciation of inorganic tellurium in seawater.

Topics: Magnetics; Mass Spectrometry; Nanoparticles; Organosilicon Compounds; Seawater; Silanes; Silicon Dioxide; Solid Phase Extraction; Spectrophotometry, Atomic; Tellurium

A novel and facile preparation method for layer-by-layer (LbL) self-assembled films incorporating quantum dots (QDs) and having intense photoluminescence (PL) from blue to red is presented. Functional sol-gel-derived glass layers prepared by the hydrolysis of 3-aminopropyltrimethoxysilane (APS) or 3-mercaptopropyltrimethoxysilane (MPS) have been used as a linkage between QD layers. Absorption, PL spectroscopy, transmission electron microscopy, and atomic force microscopy were employed for characterization, which revealed that the QDs in the prepared films had a nearly close-packed coverage and were not aggregated. The PL efficiencies of the QDs (CdTe or ZnSe, both are thioglycolic acid-stabilized) dispersed in the films were roughly half that of the initial colloidal solutions but reached 24% before a refractive index correction. The thickness of the red-emitting film with 10 CdTe QD layers was approximately 50 nm. The concentration of QDs in the film derived from the first absorption peak was approximately 0.01 M. Because the PL starts to show a red shift, the obtained concentration is practically the ultimate one in the glass matrix. The mercapto, amino, and carboxyl groups play important roles in LbL self-assembling processes.

Topics: Cadmium Compounds; Glass; Hydrolysis; Luminescence; Membranes, Artificial; Organosilicon Compounds; Particle Size; Photochemistry; Propylamines; Quantum Dots; Selenium Compounds; Silanes; Sulfhydryl Compounds; Surface Properties; Tellurium; Zinc Compounds