Removal process of nickel(II) by using dodecyl sulfate intercalated calcium aluminum layered double hydroxide

Abstract Calcium aluminum layered double hydroxides (LDH) modified with sodium dodecyl sulfate (SDS) (Ca/Al-DS LDH) was prepared to investigate the unique removal mechanism of metal cations by organic calcium-contained LDHs. The as-prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma atomic emission spectrometer (ICP-AES) and elemental analysis (EA). Ni(II) was selected as the target metal cation and its removal kinetics could be well described by the pseudo-second-order kinetic model ( R 2 = 0.990). The maximum removal capacity of Ni(II) reached 2.45 mol/g at the LDH dosage of 0.5 g L − 1 . The XRD and element analysis results indicate that a new Ni/Al-DS LDH phase and CaCO 3 were formed as well as a portion of Ca/Al-DS LDH remained in the final products after the removal process. Therefore, the removal of Ni(II) was contributed to the surface complexation, isomorphic substitution and sorption on the CaCO 3 . The pillared interlayer organic anions might help to keep the layered structure of LDH. This study revealed the multi-interaction mechanism of metal ions with Ca/Al LDH and proposed a novel strategy to generate organic intercalated LDHs by isomorphic substitution.