Synthesis of zinc oxide–montmorillonite composite and its effect on the removal of aqueous lead ions

https://doi.org/10.1007/s11631-018-0285-4

• Davidson E. Egirani
  • 1

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• Nanfe R. Poyi
  • 2
• Napoleon Wessey
• 1.Faculty of ScienceNiger Delta UniversityWilberforce IslandNigeria
• 2.Nigerian Institute of Mining and GeosciencesJosNigeria
  

  Abstract

  Lead adsorption of zinc oxide-coated ACOR montmorillonite was investigated in batches and under reducing conditions at ambient temperature. The presence of zinc oxide coating significantly enhanced the adsorption of Pb²⁺ ions by ACOR montmorillonite. Characterization of adsorbents involved the use of X-ray diffraction, sodium saturation techniques, coulter laser analysis, scanning electron microscopy, and electron dispersive spectroscopy. Synthesis involved the trimetric process, activation of the ACOR montmorillonite and reacting of the same with zinc nitrate to produce a zinc oxide composite solid at 450 °C. The reaction mechanism indicated less than one proton coefficient, and higher mass transfer rates, when compared with bare montmorillonite. Intraparticle diffusion was higher than the value recorded for the bare montmorillonite. Reactions based on initial Pb²⁺ concentration indicated that coated montmorillonite gradually became saturated as the concentration was increased. Reactions based on solid concentration demonstrated a complex change in the capacity of adsorption over different Pb²⁺ concentrations (10–40 mg L⁻¹) and solid concentrations (2–10 g L⁻¹). The specific surface area reduction, particle size increase, mineral aggregation, and concentration gradient effect controlled the complex changes in adsorption.