Multifunctional magnetic composite: MgAl-layered double hydroxide, activated carbon and magnetite on removing both different charged-dyes

Abstract

The activated carbon (AC) prepared from the shells of coconut and palm, and MgAl-layered double hydroxide (MgAl-LDH) were performed as the adsorbent for removing cationic (methylene blue) and anionic (orange II) dyes in water. The precursors of AC, MgAl-LDH and Fe3O4 were mechanically mixed to provide the magnetic composites, which were investigated by XRD, FT-IR, SEM, elemental mapping, BET, VSM, zeta potential and UV–VIS. The composites showed the characteristics and the synergistic effects of AC, MgAl-LDH and Fe3O4 with large specific surface area (320 – 330 m2/g) due to AC and MgAl-LDH, and high magnetization (12.5 – 14.4 emu/g) due to Fe3O4. The composite adsorbents revealed the bifunctional active-surface on removing both methylene blue (qm = 568 – 625 mg/g) and orange II (qm = 518 – 550 mg/g) based on monolayer coverage, and pseudo-second order reaction and spontaneous process. After 5th cycle, the adsorption capacity was reduced just 6.0 – 9.3 % with high performance on the structure and magnetism.