Sorption of lead from aqueous solutions by a commercially available tungsten trioxide nanopowder

Abstract

A commercially-available tungsten trioxide nanopowder was investigated and shown to be an excellent sorbent for Pb²⁺ ions in water. The sorption kinetics were investigated using a graphite furnace atomic absorption spectrometer. The results were analyzed using both pseudo first and second-order models. The molar sorption capacity of WO₃ nanopowder for Pb²⁺ was shown to be 36%. The nature of the starting material in solution was explored by dynamic light scattering (DLS). The morphology of the materials before and after reaction with lead were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), showing the starting materials undergo a large morphological change after the reaction with Pb²⁺. The material after reacting with excess lead was also characterized by powder X-ray diffraction (XRD) and Raman spectroscopy, showing the formation of crystalline stolzite, PbWO₄. Lastly, a cyclic process for the recovery of the sorbent was highlighted for the recovery of the starting material with a very high yield and permitting the toxic heavy metal to be properly disposed.