Adsorption of congo red using Mg/Fe and Ni/Fe layered double hydroxides

Abstract

Layered double hydroxides with different divalent ions i.e. Mg/Fe and Ni/Fe were synthesized using coprecipitation method at basic condition. Materials were characterized using X-Ray diffraction and FTIR analyses. Furthermore, Mg/Fe and Ni/Fe layered double hydroxides were applied as adsorbent of Congo red dye in aqueous medium using batch system. Adsorption of Congo red on layered double hydroxides was investigated through kinetic and thermodynamic studies. X-ray diffraction analysis showed that unique diffraction of layered materials were identified at 2θ diffraction 11.33°, 29.55°, 59.66° (Mg/Fe) and 11.41°, 29.40°, 60.40° (Ni/Fe). Interlayer distance of Mg/Fe and Ni/Fe layered double hydroxides was 7.80 Å and 7.75 Å, respectively. IR spectrum of Mg/Fe and Ni/Fe layered double hydroxides showed that vibration of layered material was appeared at 1381 cm−1 (νN-O; nitrate), 347 cm−1 (νMg-O; layered double hydroxides), 586 cm−1 (νFe-O; layered double hydroxides) for Mg/Fe and 1381 cm−1 (νN-O; nitrate), 493 cm−1 (νNi-O; layered double hydroxides), 516 cm−1 (νFe-O; layered double hydroxides) for Ni/Fe. Kinetic pseudo second order was fitted than pseudo first order kinetic model for adsorption of Congo red with R ± 0.99 for both Mg/Fe and Ni/Fe. The rate of adsorption K2 for Mg/Fe and Ni/Fe layered double hydroxides was 0.008 g.mg−1min−1 and 0.0058 g.mg−1min−1. Adsorption of Congo red on Mg/Fe and Ni/Fe layered double hydroxides was well described and following Freundlich adsorption isotherm model shows physical adsorption process on layered double hydroxides.