Kinetics of urease mediated calcite precipitation and permeability reduction of porous media evidenced by magnetic resonance imaging
| Autor: | Michael L. Johns, Joanna C. Renshaw, E. Sham, Lynne E. Macaskie, S. Nougarol, Stephanie Handley-Sidhu, Mark O. Cuthbert, Michael D. Mantle |
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| Rok vydání: | 2013 |
| Předmět: |
Calcite
Environmental Engineering biology Urease Analytical chemistry chemistry.chemical_element Mineralogy Calcium biology.organism_classification Sporosarcina pasteurii chemistry.chemical_compound chemistry Permeability (electromagnetism) Canavalia ensiformis biology.protein Environmental Chemistry Carbonate Ammonium General Agricultural and Biological Sciences |
| Zdroj: | International Journal of Environmental Science and Technology. 10:881-890 |
| ISSN: | 1735-2630 1735-1472 |
| Popis: | The enzyme urease drives the hydrolysis of urea leading to the release of ammonium ions and bicar- bonate; in the presence of calcium, the rise in pH leads to increased calcium carbonate saturation and the subsequent precipitation of calcite. Although such alkalinizing ureol- ysis is widespread in nature, most studies have focussed on bacteria (i.e. indigenous communities or urease-active Sporosarcina pasteurii) for calcite precipitation technolo- gies. In this study, urease-active jack bean meal (from the legume Canavalia ensiformis) was used to drive calcite precipitation. The rates of ureolysis (kurea), determined from measured NH4 ? , enabled a direct comparison to microbial ureolysis rates reported in literature. It is also demonstrated that a simple single reaction model approach can simulate calcite precipitation very effectively (3-6 % normalised root-mean-square deviation). To investigate the reduction of permeability in porous media, jack bean meal (0.5 g L -1 ) and solutions (400 mM urea and CaCl2) were simultaneously pumped into a borosilicate bead column. One-dimensional magnetic resonance profiling techniques were used, non-invasively, for the first time to quantify the porosity changes following calcite precipitation. In addi- tion, two-dimensional slice selective magnetic resonance images (resolution of *0.5 9 1.0 mm) revealed that the exact location of calcite deposition was within the first 10 mm of the column. Column sacrifice and acid digestion also confirmed that 91.5 % of calcite was located within the first 14 mm of the column. These results have impor- tant implications for the design of future calcite precipi- tation technologies and present a possible alternative to the well known bacterial approaches. |
| Databáze: | OpenAIRE |
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