Phenols removal from water by precursor preparation for Mg-Al layered double hydroxide: Isotherm, kinetic and mechanism

Precursor of Mg-Al LDH was simply obtained by dry milling of Al(OH)(3) and Mg(OH)(2) in two-step process and used as adsorbent to remove phenol and p-nitrophenol from water. The precursor samples before and after adsorption were characterized through Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The equilibrium adsorption data were well fitted to Langmuir model and were characterized with excellent adsorption capacities of 82.6 mg/g phenol and 356.4 mg/g p-nitrophenol, respectively. Pseudo-second-order kinetic model indicated that phenols were well adsorbed on the precursor. The enhanced adsorption mechanism was investigated and observed that the disorderly precursor have more active sites than the other adsorbents with stable crystalline structures. Comparison between the precursor and LDH product clearly demonstrated the advantage of precursor over the LDH, providing a new concept of using the easily obtained precursor as efficient adsorbent for wastewater treatment.