Highly efficient removal of uranium (VI) from aqueous solutions using poly(acrylic acid)-functionalized microspheres

• A new adsorbent was developed for highly efficient removal of U (VI) in waste water.
• The adsorbent had the controlled density and length of PAA chain on the surface.
• The higher density and longer chain of PAA, the more effective to adsorb uranyl ion.
• The adsorption could be well described with pseudo-second-order kinetics equation.
• The maximum adsorption capacity could reach 990 mg/g for uranium (VI) at 25 °C.

Uranium (VI) is highly toxic and radioactive in water, and may pose the great risk to human health and environment. A new adsorbent is reported here for highly efficient removal of uranyl ions from aqueous solution. Specifically, poly(acrylic acid)-block-polystyrene (PAA-b-PSt) block copolymers were synthesized as macromolecular surfactant for the emulsion polymerization of styrene. The obtained PSt microspheres had the controlled density and length of PAA chain on the surface, which lead to a controlled high adsorption capacity. The effects of pH, adsorbent dose, coexisting ions, temperature, contact time, initial concentration were evaluated on the removal of uranyl ions. Adsorption equilibrium could be achieved within 4 h, and the kinetic data could be well described by pseudo-second-order kinetics equation, and the maximum adsorption capacity calculated from Langmuir equation was ∼990 mg/g at 298.15 K and pH 4.5. This work indicates that PAA-functionalized microspheres can be used as a new adsorbent for highly efficient removal of uranium (VI) from aqueous solutions.

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