Starch-NiFe-layered double hydroxide composites: Efficient removal of methyl orange from aqueous phase

Starch-NiFe-layered double hydroxide (S/NiFe-LDH) composite was prepared via co-precipitation method and employed as an adsorbent for the removal of anionic dye methyl orange (MO) from aqueous solution. Two hybrids with different ratio of starch and NiFe-LDH were prepared i.e. S/NiFe-LDH (1:1) and S/NiFe-LDH (2:1) and their adsorption performance was compared with NiFe-LDH. The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The effects of influential adsorption parameters such as pH, initial MO concentration contact time and adsorbent dosage on the removal of MO were studied. The starch-NiFe-LDH composite was efficient in removing MO from water and maximum removal of 99 and 90% was observed at pH 3 by S/NiFe-LDH (1:1), S/NiFe-LDH (2:1), respectively. The maximum adsorption capacities of NiFe-LDH, S/NiFe-LDH (2:1) and S/NiFe-LDH (1:1), calculated from Langmuir isotherm, were 246.91 mg/g, 358.42 mg/g, 387.59 mg/g respectively. The adsorption kinetics of MO on the surface of S/NiFe-LDH composites was best fitted by pseudo-second-order model. Starch-NiFe-LDH was easily regenerated with aqueous solution of NaOH with a minor loss in adsorption capacity up to four cycles.