Biphenyl-bridged wrinkled mesoporous silica nanoparticles for radioactive iodine capture
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.75
Biphenyl-bridged wrinkled mesoporous silica nanoparticles for radioactive iodine capture Alexander T. Brown,a Jason Lin,a Milana C. Thomas,b Yves J. Chabal,b and Kenneth J. Balkus Jr a,* a Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Rd, Richardson, TX 75080, USA
b Department of Materials Science and Engineering, The University of Texas at Dallas, 800 West Campbell Rd, Richardson, TX 75080, USA
ABSTRACT
The capture of volatile radioactive iodine-129 is an important process for nuclear fission. Biphenyl-bridged wrinkled mesoporous silica shows similar performance for iodine sequestration to commercial Ag-mordenite and avoids the use of expensive silver. The biphenyl-wrinkled mesoporous silica nanoparticles function as a scaffold for biphenyl groups and also as a fluorescent indicator for the loading of iodine. The nanoparticles have a surface area of 973 m2/g and the biphenyl molecules form an electron charge-transfer complex with iodine. Iodine was loaded into the biphenyl-bridged wrinkled mesoporous silica (BWMS) at 19 ± 0.2 % loading by mass.
INTRODUCTION The industrial sequestration of radioactive 129iodine and organic iodine species are inherent hazardous byproducts from nuclear fission [1]. Some of the issues with the recovery process are the highly acidic conditions and substantial monetary cost to capture 129I. Current technology primarily uses Ag-zeolite structures for 129I binding as the Ag in the zeolite forms a charge transfer complex with iodine [2]. Also, some polymers and metal organic frameworks have been functionalized with molecules to form charge complexes with iodine [3, 4]. The mesoporous silica structure, SBA 15, with embedded bismuth has been also been investigated for iodine capture [5]. Also, Fe3O4 [6] and ZIF-8 [7] nanoparticles were each embedded into a polymer matrix and used to adsorb molecular iodine. We have prepared wrinkled mesoporous organosilica (BWMS)
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containing bridging organosilanes that fluoresce and form electron charge transfer complexes with iodine. In this paper the synthesis and characterization of wrinkled silica containing 25 wt% biphenyl bridging silanes as well as the interaction with iodine is discussed. EXPERIMENTAL DETAILS Materials All chemicals were commercially obtained and used without further purification. Urea was purchased from Mallinckrodt AR, cyclohexane from EMD Millipore Corporation, tetraethyl orthosilicate (98 %) from Acros, and concentrated hydrochloric acid and ethanol (200 proof) from Fisher Scientific. Isopropyl alcohol ( 99.7%), hexadecylpyridinium bromide ( 97 %), and 4,4’-bis(triethoxysilyl)-1,1’biphenyl were sourced from the Sigma-Aldrich Corporation. Synthesis of bip
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