Analysis of precipitates from reactions of hyperalkaline solutions with soluble silica |
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| Institution: | 1. Department of Crop and Soil Sciences, Center for Multiphase Environmental Research, Washington State University, Pullman, WA 99164, USA;2. Pacific Northwest National Laboratory, Environmental Molecular Science Laboratory, Richland, WA 99352, USA;1. Department of Biosystems and Agricultural Engineering, Michigan State University, 524 S. Shaw Lane, Room 216, East Lansing, MI 48824, USA;2. Department of Civil Engineering, University of Sulaimani, Sulaimani, KRG, Iraq;3. Department of Plant, Soil and Microbial Sciences, Michigan State University, 1066 Bogue Street, Room A286, East Lansing, MI 48824, USA;1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China;2. School of Environment, Tsinghua University, Beijing 100084, China;1. State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090, China;2. Department of Environmental Engineering, School of Food Engineering, Harbin University of Commerce, Harbin 150076, China;3. School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China;1. Civil Engineering, The Catholic University of America, 630 Michigan Ave NE, Washington, DC 20064, USA;2. DC Water and Sewer Authority, 5000 Overlook Avenue, SW, Washington, DC 20032, USA;3. Dynamita, 7 lieu-dit Eoupe, 26110 Nyons, France;1. Unidad Académica Río Gallegos de la Universidad Nacional de la Patagonia Austral, Argentina;2. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT-La Plata-CONICET, Universidad Nacional de La Plata, Diag 113 y 64, La Plata, Argentina;3. Departamento de Química, Universidad Nacional de Río Cuarto, Campus Universitario, Río Cuarto, Argentina;1. Department of Inorganic and Analytical Chemistry, University of Szeged, 7 Dóm tér, H–6720 Szeged, Hungary;2. Department of Physical Chemistry and Material Science, University of Szeged, 1 Rerrich Béla tér, H–6720 Szeged, Hungary;3. Department of Organic Chemistry, University of Szeged, 8 Dóm tér, H–6720 Szeged, Hungary |
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| Abstract: | Cancrinite, sodalite, and zeolite A have been found to form upon contacting hyperalkaline simulated tank waste (STW) with vadose zone sediments from the Hanford Reservation. Here, soluble silica and STW are used to study mineral formation and transformation. Two Hanford sediment fractions (diameters <50 and >50 μm instead of soluble silica) are also used as silica sources for comparison. A series of batch experiments at 50 °C and 25 days duration were conducted by reacting 0.026 mol/kg soluble Si with 6 different STW solutions. The STW solutions differed in NaOH and Al concentrations. Cancrinite, sodalite, and zeolite A formed when soluble Si was used as the Si source. The minerals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and 27Al and 29Si magic-angle spinning nuclear magnetic resonance (MAS-NMR). Larger NaOH and Al concentrations favored formation of the more compact structures of cancrinite and sodalite. At larger NaOH concentration more Al for Si substitution occurred in the tetrahedral sites. A greater Al(4)/Al(6) ratio in the solids was found for the higher Si/Al ratio solutions based on NMR results. Mixtures of cancrinite and sodalite were characterized by particles with lepispheric morphology. At low Al concentration, increasing NaOH resulted in distinct hexagonal, prismatic particles common to crystalline cancrinite. At low Al/Si ratio, the characteristic cubic morphology of zeolite was observed in addition to cancrinite and sodalite. |
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