Adsorption of Lanthanum (La) and Samarium (Sm) by Diatomaceous Earth

The Jordanian diatomaceous earth (DT) has been modified by a quaternary ammonium salt; hexadecyltrimethylammonium bromide in order to prepare the organically modified diatomaceous earth (DT-HDTMA). DT and DT-HDTMA were used for adsorption of lanthanum La(III) and samarium Sm(III) ions from aqueous solutions. Both adsorbents were evaluated by measuring the surface area (SA), cation exchange capacity (CEC), Fourier transform infrared (FTIR), X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence (XRF) and scanning electron microscope (SEM). Adsorption of La(III) and Sm(III) ions onto DT and DT-HDTMA was studied using batch technique as a function of initial concentration of metal cations, adsorbent dosage, ionic strength, initial pH solution, contact time and temperature. The isothermal behavior of the metal ions uptake properties were studied using Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption isotherms. DT-HDTMA showed high-metal ion uptake capacity toward La(III) and Sm(III) ions compared with unmodified diatomaceous earth.