Development and application of carbon nanotubes reinforced hydroxyapatite composite in separation of Co(II) and Eu(III) ions from aqueous solutions

Multi-walled carbon nanotubes/strontium hydroxyapatite (MWCNT/SH) composite was synthesized, where CNTs were applied to improve the properties of HAP and increase the reinforcement of the composite. The composite CNTs/Sr-HAP and its precursor Sr-HAP were successfully applied in removal of Co(II) and Eu(III) ions from aqueous solutions. Sorption of Co(II) and Eu(III) onto the synthesized sorbents was investigated as a function of contact time and pH. The synthesized sorbents highly removed the studied radionuclides from their aqueous solutions with necessary time of 6 h to reach equilibrium. The maximum sorption capacity was 33.31 and 48.93 mg g(-1) for Co(II) sorption onto Sr-HAP and CNTs/Sr-HAP composite at pH 4.5, while it was 115.74 and 127.11 mg g(-1) for sorption of Eu(III) onto Sr-HAP and CNTs/ Sr-HAP composite at pH 2.5, respectively. Desorption of Co(II) and Eu(III) from loaded samples was studied using various eluents and maximum recovery was obtained using FeCl3 and HCl solutions. Co(II) was completely separated from Eu(III) by a ratio of 85.1 % using Cd(NO3)(2) as an eluent in CNTs/Sr-HAP composite packed column.