Synthesis and characterization of alumina-coated carbon nanotubes and their application for lead removal.

Alumina-coated multi-wall carbon nanotubes were synthesized and characterized by scanning electron microscopy, X-ray diffraction, and FTIR. They were used as an adsorbent for the removal of lead ions from aqueous solutions in two modes, batch and fixed bed. In the batch mode, experiments were carried out to investigate the effect of contact time, agitation speed, adsorbent dosage and solution pH on the removal of lead. The coated nanotubes exhibit better removal ability over uncoated. For fixed-bed columns, thickness of the layer and flow rate were investigated. Increasing the thickness and decreasing the flow rate enhanced the removal of lead. The prepared adsorbent displayed the main advantage of separation convenience when a fixed-bed column was used compared to the batch adsorption treatment.