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The MgAl-LDH adsorbent (2:1) was developed by the urea method and used as an adsorbent for the removal of methyl orange from aqueous solution. The synthesized adsorbent was characterized by a different analytical technique: scanning electron microscope SEM, X-ray diffraction (XRD) and infrared spectroscopy (FT-IR). The effect of adsorption parameters such as solution pH, initial concentration of dye, and the temperature was studied using a static system. X-ray diffraction analysis of the samples confirms the crystal structure of the MgAl-LDH material. The MgAl-LDH adsorbent was efficient in removing MO from aqueous solution, and maximum removal of 98.5 % was observed in the pH range from 2 to 10. The maximum adsorption capacity of MgAl-LDH (2:1) was calculated from the Langmuir isotherm; the maximum quantity is 1250 mg. g-1. The determination of the thermodynamic parameters indicates that the reaction between methyl orange and MgAl-LDH (2:1) is spontaneous and exothermic (ΔH°<0 and ΔG°<0).It can be concluded that LDH adsorbent can be used effectively for the removal of anionic dyes from industrial wastewater.

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The objective of this work is to determine the kinetic and thermodynamic properties of adsorption of Pb(II) from aqueous solutions by synthetically prepared MgFeAl-CO 3 as layered double hydroxide (LDH) adsorbent. Compared to other adsorbents for heavy metal removal from aqueous solutions, LDH materials possessed many advantages such as nontoxic synthesis, chemical stability, environmentally friendly, and facile separation from the water solution. The synthesis of LDH was achieved by a co-precipitation method. The reaction products were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive spectroscopy and N 2 sorption-desorption isotherm analysis. The adsorption rates were investigated. The effect of the parameters such as contact time, initial metal ion concentration, and temperature on the adsorption of the Pb(II) was studied. Equilibrium was achieved in 60 min and the equilibrium adsorption capacity was found to be increased with the increase in the Pb(II) initial concentration. The removal efficiency of Pb(II) increases from 59.50% to 71.15% when the temperature increases from 15°C to 60°C. The pseudo-first-order, pseudo-second-order, and Elovich kinetic models were tested and the first was found to fit better to the experimental data. The application of the intra-particle diffusion model demonstrates that the surface diffusion and the intra-particle diffusion occur in parallel during the adsorption of Pb(II) onto MgFeAl-CO 3 . The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. The results indicated that the Redlich-Peterson and Langmuir isotherms were the most suitable models for the obtained experimental data and the Langmuir maximum adsorption capacity of the MgFeAl-CO 3 is found to be 117.86 mg g -1 at 298.15 K. The thermodynamic analysis of the adsorption of Pb(II) on MgFeAl-CO 3 reveals that the present adsorption process is a spontaneous and endothermic reaction.

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