Uranium(VI) adsorption from aqueous solutions using poly(vinyl alcohol)/carbon nanotube composites

Poly(vinyl alcohol)/multiwalled carbon nanotubes (PVA/MWCNTs) composite hydrogels were prepared by a dispersion method and their ability to adsorb and remove uranyl ions from aqueous solutions was investigated. The prepared composites were characterized by XRD, TEM, SEM and FTIR. The effect of contact time, solution pH, initial UO22+ ion concentration and temperature on UO22+ ion adsorption from aqueous solution onto the prepared hydrogels was studied. The obtained results illustrated that, dispersion of MWCNTs into the PVA matrix enhanced the removal efficiency of UO22+ ions compared to PVA only. The Langmuir and Freundlich adsorption models have been applied to evaluate the adsorption efficiency and the data correlated well with the Langmuir model. Thermodynamic parameters (Delta H degrees, Delta S degrees, Delta G degrees) were determined which indicated that the UO22+ ion adsorption process onto the prepared hydrogels was exothermic and spontaneous. The adsorbed UO22+ can be desorbed effectively by 0.1 M EDTA.