Synthesis of Ni-Fe-CO$_3$ layered double hydroxide as Effective Adsorbent to remove Cr(VI) and ARS-dye from aqueous media

Ni$^2$/Fe$^{3＋}$LDH, (Ni-Fe-CO3 LDH) with Ni/Fe molar ratio 3.0 was synthesized by co-precipitation for the remediation of chromium (VI), and Alizarine Red-S (ARS-dye) as anionic species. The investigated adsorbent was characterized by TGA, SEM, XRD, BET and FTIR. The effect of the hydrogen ion concentration of the medium, shaking time, ARS-dye and/or Cr(VI) concentration and adsorbents mass on the process was studied. The results of Ni-Fe-CO$_3$ LDH fitted well with the pseudo-second-order model. Langmuir isotherm is more favor than the Freundlich isotherm with maximum capacity ($Q_{max}$) of 69.9 and 6.1 mg/g for ARS-dye and Cr(VI), respectively.