A New Hydrotalcite-Like Absorbent OSA-LDH and Its Adsorption Capacity for Pb²⁺ Ions in Water

Abstract

Hydrotalcite-like materials (OSA-LDH) were prepared used oil shale ash (OSA), which came from a thermal power plant area, as the main raw material. The characterization results of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and thermogravimetric-differential scanning calorimetry (TG-DSC) showed that the prepared samples were mesoporous materials in a crystal state and were layered and contained lattice oxygen and a large number of surface hydroxyl groups. The adsorption property of the prepared samples was confirmed and evaluated by adsorption experiments with Pb2+ as the target pollutant. The adsorption process was in accord with the Langmuir isothermal adsorption equation, and the adsorption data fitted perfectly with the pseudo-second kinetic equation. The saturated adsorption capacity for Pb2+ was 120.92 mg·g−1 at a temperature of 298 K and initial concentration of 300 mg·L−1. The main adsorption mechanisms of OSA-LDH for Pb2+ were chemical bond cooperation and electrostatic bond cooperation. This paper aimed to not only prepare an economical and effective adsorbent to remove heavy metal ions from the solution but also provide a new path for the treatment and utilization of OSA so as to realize efficient waste resource utilization.

Keywords

• oil shale ash (OSA)
• hydrotalcite-like materials (LDH)
• adsorption
• Pb²⁺