Water decontamination via the removal of Pb (II) using a new generation of highly energetic surface nano-material: Co+2Mo+6 LDH

The current work reports the preparation of CoMo(CO32−) layered double hydroxide (LDH) of a highly energetic surface as a new type of the mixed divalent and hexavalent metals (M+2M+6). The surface morphology of the prepared material was examined through scanning electron microscope (SEM). The prepared LDH had exhibited a highly energetic surface due to the formation of +4 surface charges in the brucite layer between Co+2 and Mo+6, demonstrated via the X-ray photoelectron spectroscopy (XPS). The prepared material was then introduced as a novel adsorbent for the removal of lead ions (Pb+2) from an aqueous solution at different experimental conditions of time, temperature and (Pb+2) concentrations. The experimental results had exhibited a promising adsorption capability of the prepared materials in terms of the overall rate of removing the (Pb+2) that was attained. In particular, a maximum value of 73 mg/g of the lead ions concentration was removed within an interaction time of 30 min and at room temperature while using adsorbent/solution ratio of 5 g/L. This value had represented a removal percentage of approximately 99.2% since that the original aqueous solution had contained initial Pb+2 concentration of 369.9 mg/L. The mechanism of the adsorption of Pb+2 by the synthesized LDH had been highly likely orientated toward the surface adsorption route in which the lead molecules had accumulated onto the Co Mo LDH surface. This mechanism could be probably due to the effect of the coordination bonding between the nitrate counter ions and the Mo+4 in the Co Mo brucite layers. The isothermal and kinetics data of the adsorption of Pb+2 by the prepared Co Mo LDH were well fitted by the pseudo-second-order model and Langmuir equation respectively. Lastly, the introduced material through this work had showed a great degree of sustainability (over 7 times of utilization) with a complete conservation of its parental morphology and adsorption capacity. The suggested mechanism for the surface adsorption of the Pb+2 onto the CoMo(CO3) LDH combined with the LDH capacity towards the removal of lead ions.139