Mercury binding sites in thiol-functionalized mesostructured silica.
نویسندگان
چکیده
Thiol-functionalized mesostructured silica with anhydrous compositions of (SiO(2))(1)(-)(x)()(LSiO(1.5))(x)(), where L is a mercaptopropyl group and x is the fraction of functionalized framework silicon centers, are effective trapping agents for the removal of mercuric(II) ions from water. In the present work, we investigate the mercury-binding mechanism for representative thiol-functionalized mesostructures by atomic pair distribution function (PDF) analysis of synchrotron X-ray powder diffraction data and by Raman spectroscopy. The mesostructures with wormhole framework structures and compositions corresponding to x = 0.30 and 0.50 were prepared by direct assembly methods in the presence of a structure-directing amine porogen. PDF analyses of five mercury-loaded compositions with Hg/S ratios of 0.50-1.30 provided evidence for the bridging of thiolate sulfur atoms to two metal ion centers and the formation of chain structures on the pore surfaces. We find no evidence for Hg-O bonds and can rule out oxygen coordination of the mercury at greater than the 10% level. The relative intensities of the PDF peaks corresponding to Hg-S and Hg-Hg atomic pairs indicate that the mercury centers cluster on the functionalized surfaces by virtue of thiolate bridging, regardless of the overall mercury loading. However, the Raman results indicate that the complexation of mercury centers by thiolate depends on the mercury loading. At low mercury loadings (Hg/S < or = 0.5), the dominant species is an electrically neutral complex in which mercury most likely is tetrahedrally coordinated to bridging thiolate ligands, as in Hg(SBu(t))(2). At higher loadings (Hg/S 1.0-1.3), mercury complex cations predominate, as evidenced by the presence of charge-balancing anions (nitrate) on the surface. This cationic form of bound mercury is assigned a linear coordination to two bridging thiolate ligands.
منابع مشابه
Adsorption Properties of Thiol-Functionalized Silica Nanoparticles Prepared for Application in Poly(ether sulfone) Nanocomposite Membranes
متن کامل
Thiol-functionalized mesoporous silica as nanocarriers for anticancer drug delivery
The present study deals with the synthesis andfunctionalization of mesoporous silica nanoparticles as drug delivery platforms. SBA-15 nanorods with high surface area (1010 m2g-1) were functionalized by post grafting method using 3-mercaptopropyl trimethoxysilane (MPTS). The parent and thiol-functionalized SBA-15 nanorods were used as nanocarriers for an anticancer drug (gemcitabine). The charac...
متن کاملThiol-functionalized mesoporous silica as nanocarriers for anticancer drug delivery
The present study deals with the synthesis andfunctionalization of mesoporous silica nanoparticles as drug delivery platforms. SBA-15 nanorods with high surface area (1010 m2g-1) were functionalized by post grafting method using 3-mercaptopropyl trimethoxysilane (MPTS). The parent and thiol-functionalized SBA-15 nanorods were used as nanocarriers for an anticancer drug (gemcitabine). The charac...
متن کاملApplication of Nanoanalysis: Amine-Functionalized Mesoporous Silica nanoparticles for Mercury Speciation in Human Samples
Mercury (Hg) causes hazardous cumulative effects in humans; like central nervous system disorders,hypertension and chromosomal aberrations. Therefore, due to high toxicity and bioaccumulationfactor, mercury determination and speciation in human blood is very important. A sensitive,accurate, precise and inexpensive method was demonstrated for preconcentration and speciationof ultra-trace mercury...
متن کاملSynthesized mercaptopropyl nanoporous resins in DGT probes for determining dissolved mercury concentrations.
3-Mercaptopropyl functionalized SBA-15 (SH-SBA) and 3-mercaptopropyl functionalized ethenylene bridged periodic mesoporous organosilica (SH-PMO) were included in a Diffusive Gradients in Thin film (DGT) probe and compared to similar commercially available resins also containing thiol functional groups, such as Sumichelate Q10R (SQR) and 3-mercaptopropyl functionalized silica gel (SH-KG), and al...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 127 23 شماره
صفحات -
تاریخ انتشار 2005