Glenn A. Fox

Polymer pendant crown thioethers: synthesis, characterization and Hg2+ extraction studies of polymer-supported thiacrowns ([14]aneS4 and [17]aneS5)

Abstract We are interested in designing polymer-bound extractants for Hg 2+ remediation in mixed-waste streams. Towards this goal, we have synthesized novel polymer extractants where 2-aminomethylthiacrowns are immobilized on a polystyrene–divinylbenzene matrix through the pendant arm of the crowns. Reaction of 2,3-dimercapto-1-propanol with either 4,7-dithiadecane-1,10-di- p -toluenesulfonate or 4,7,10-trithiatridecane-1,13-di- p -toluenesulfonate generated the 2-hydroxymethylthiacrowns, 3 ([14]aneS 4 -OH) and 4 ([17]aneS 5 -OH). Treatment of the 2-hydroxymethylthiacrowns with thionyl chloride, followed by monomethylamine, produced the N-(methyl)-2-aminomethylthiacrowns, 5 ([14]aneS 4 -NR 1 R 2 ) and 6 ([17]aneS 5 -N R 1 R 2 ) (R 1 =Me, R 2 =H). The thiacrown polymers were prepared through the copolymerization of a 4-vinylbenzyl-substituted aminomethylthiacrown, 7 ([14]aneS 4 -N R 1 R 2 ) or 8 ([17]aneS 5 -N R 1 R 2 ) (R 1 =Me, R 2 =4-vinylbenzyl), with divinylbenzene. Extraction of Hg 2+ from aqueous media using the [17]aneS 5 thiacrown polymer 10 with under a variety of conditions ([Hg 2+ ] 4–200 ppm, pH 1.5–6.2) shows that the resin effectively and selectively removes Hg 2+ ions from acidic aqueous solutions with extraction efficiency ∼95%. Mercury recovery and polymer regeneration was also demonstrated using chloroform solutions of diphenylthiocarbazone to strip the bound Hg 2+ from the resin.

Solution preparation of Ge nanoparticles with chemically tailored surfaces

Boyd R. Taylor *, Glenn A. Fox , Lousia J. Hope-Weeks , Robert S. Maxwell , Susan M. Kauzlarich , Howard W.H. Lee d a Chemistry and Chemical Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA b Analytical and Nuclear Chemistry Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA c Chemistry Department, University of California, One Shields Avenue, Davis, CA 95616, USA d UltraPhotonics Inc., 48611 Warm Springs Blvd. Fremont, CA 94536, USA

X-ray photoemission investigation of binding sites in polymer-bound thiacrowns used for environmental remediation of Hg in aqueous solutions

Abstract X-ray photoemission spectroscopy has been used to examine how Hg is bound to a polymer-bound thiacrown shown to be effective in extracting HgII from acidic aqueous solutions. High resolution Hg 4f and S 2p core-level spectra were acquired for a set of well-characterized sulfur-containing model compounds and their corresponding Hg complexes. Results from these materials were used to interpret the Hg 4f and S 2p core-level spectra of the polymer-bound thiacrown material, the thiacrown monomeric precursors and the Hg-containing reacted polymer. The thiacrown structure was found to be unaffected by incorporation into the polymer and Hg appears to be bound to the polymer complex in a similar manner as Hg is bound in monomeric thiacrowns containing five sulfur atoms.

X-Ray absorption spectroscopy of thiacrown compounds used in the remediation of mercury contaminated water

Effective methods for the removal of mercury from water are in demand due to the high levels of mercury released from industrial and natural processes. Polymer pendant thiacrown compounds used for the sequestration of Hg(II) from aqueous solutions have shown great promise as effective tools for remediation. Three thiacrowns that have been used for mercury chelation, [18]aneS6 and [17]aneS5-polymer (with divinylbenzene) at two Hg(II) loadings, were examined by X-ray absorption spectroscopy in an attempt to determine the bonding configuration between the sulfurs of the thiacrown and the mercury. For Hg[18]aneS6, it was found that four of the possible six crown sulfur atoms were involved in mercury bonding. For the Hg[17]aneS5-polymer, it was found that three of the possible five crown sulfur atoms were involved in mercury bonding. These thiacrown components appear to form stable mercury complexes and should be effective agents for sequestering and potential recycling of mercury from water.