Evaluation of CNTs/MnO2 composite for adsorption of 60Co(II), 65Zn(II) and Cd(II) ions from aqueous solutions

CNTs/MnO2 composite was synthesized by a coprecipitation method after preparation of carbon nanotubes (CNTs) using a chemical oxidation method and was characterized using Fourier transformer infrared (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The synthesized CNTs/MnO2 composite was used as a sorbent for the removal of some radionuclides (Co-60 and Zn-65-radioisotopes) and Cd (II) ions from aqueous solutions. Different parameters affecting the removal process including pH, contact time and metal ion concentration were investigated. Isotherm and kinetic models were studied. Adsorption data was interpreted in terms of both Freundlich and Langmuir isotherms and indicated that the CNTs/MnO2 composite complied well with both Langmuir and Freundlich models for Co-60 and Cd(II) ions and with the Freundlich model only for the Zn-65 radioisotope. A pseudo-second-order model was effectively employed to describe the adsorption behavior of Co-60, Zn-65 and Cd(II) ions. Desorption of Co-60 and Zn-65 and Cd(II) ions from loaded samples was studied using different eluents.