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Removing Uranium (VI) from Aqueous Solution With Insoluble Humic Acid Derived from Leonardite

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Technical Report

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ERDC Vicksburg

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The occurrence of uranium U and depleted uranium DU-contaminated wastes from anthropogenic activities is an important environmental problem. Insoluble humic acid derived from leonardite L-HA was investigated as a potential adsorbent for immobilizing U in the environment. The effect of initial pH, contact time, U concentration, and temperature on UVI adsorption onto L-HA was assessed. The UVI adsorption was pH-dependent and achieved equilibrium in 2 h. It could be well described with pseudo second-order model, indicating that UVI adsorption onto L-HA involved chemisorption. The UVI adsorption mass increased with increasing temperature with maximum adsorption capacities of 91, 112 and 120 mg g-1 at 298, 308 and 318 K, respectively. The adsorption reaction was spontaneous and endothermic. We explored the processes of UVI desorption from the L-HA-U complex through batch desorption experiments in 1 mM NaNO3 and in artificial seawater. The desorption process could be well described by pseudo-first-order model and reached equilibrium in 3 h. L-HA possessed a high propensity to adsorb UVI. Once adsorbed, the release of UVI from L-HA-U complex was minimal in both 1 mM NaNO3 and artificial seawater 0.06 and 0.40, respectively. Being abundant, inexpensive, and safe, LHA has good potential for use as a U adsorbent from aqueous solution or immobilizing U in soils.

Subject Categories:

  • Physical Chemistry
  • Water Pollution and Control
  • Physical Chemistry
  • Water Pollution and Control

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