Highly efficient removal of three red dyes by adsorption onto Mg-Al-layered double hydroxide

The Mg-Al-CO3-LDH with Mg2+/Al3+ molar ratio of 2 was prepared via coprecipitation method at constant pH of 9-10 and used to remove three red dyes by batch adsorption method. The results showed the Mg-Al-LDH were well crystallized and can adsorb the red dyes effectively. The optimal adsorbent dosage and contact time were 1.0 g and 60 min, respectively. Adsorbed amount hardly changed when pH < 10. The adsorption kinetics fit the pseudo-second order kinetic models well and isotherms correspond to Langmuir model strictly. All the relevant mechanisms were studied and manifested as anion exchange and also electrostatic attraction for CR. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.