Magnetically modified carboxylate-rich carbonaceous composite materials: preparation and sorption of Pb(II), Ni(II), Hg(II) and U(VI)

Carboxylate-rich carbonaceous composite materials were prepared using hydrothermal method,then magnetically modified carboxylate-rich carbonaceous composite material was prepared by chemical co-precipitation process.The morphology,contents,structures,paramagnetic properties and surface charge properties of magnetic carboxylate-rich carbon have been characterized by transmission electron microscopy(TEM),Fourier transformed infrared spectrum(FTIR),X-ray diffraction(XRD),vibrating sample magnetometry(VSM),thermogravimetric analysis(TGA),zeta potential and specific surface area(BET),and sorption of Pb(Ⅱ),Ni(Ⅱ),Hg(Ⅱ) and U(Ⅵ) by carboxylate-rich carbon and magnetic carboxylate-rich carbon was also studied.Results indicate that Fe3O4 nanoparticles are absorbed to the surfaces of magnetic carboxylate-rich carbon.Its surface area increases from 29.2 m2/g to 45.4 m2/g.The introduced Fe3O4 improves thermal stability.The saturation magnetization of magnetic carboxylate-rich carbon is 30.68 A·m2/kg.The equilibrium sorption capacities of Pb(Ⅱ),Ni(Ⅱ),Hg(Ⅱ) and U(Ⅵ) on magnetic carboxylate-rich carbon are 477.50,23.50,260.20 and 54.86 mg/g,respectively,which are lower than carboxylate-rich carbon.The Langmuir isotherm is the best-fit sorption isotherm model.From the high sorption capacities of Pb(Ⅱ),Ni(Ⅱ),Hg(Ⅱ) and U(Ⅵ) on magnetic carboxylate-rich carbon and comparison of U(Ⅵ) sorption capacities on different sorbents,magnetic carboxylate-rich carbon is a promising sorption material for water treatment of heavy metal ions and radionuclides.