Kinetic study of time-dependent fixation of U VI on biochar
Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of U from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20°C, inclu...
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Published in | Journal of hazardous materials Vol. 320; p. 55 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
15.12.2016
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Subjects | |
Online Access | Get full text |
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Summary: | Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of U
from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20°C, including pH, initial concentration of U
and contact time. Uranium (U
) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH>7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of U
within the biochar structure. Desorption experiments showed that U
was only sparingly desorbable from the biochar with time and isotopic dilution with
U
confirmed the low, or time-dependent, lability of adsorbed
U
. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5-9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5. |
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ISSN: | 1873-3336 |
DOI: | 10.1016/j.jhazmat.2016.08.002 |