Fabrication of a new hydrous Zr(IV) oxide-based nanocomposite for enhanced Pb(II) and Cd(II) removal from waters

To overcome the technical bottleneck of fine hydrated Zr(IV) oxide particles in environmental remediation, we irreversibly impregnated nanosized hydrated Zr(IV) oxide inside a commercial cation exchange resin D-001 and obtained a new nanocomposite NZP. NZP exhibited efficient removal of lead and cadmium ions in a pH range of 2-6, where no Zr(IV) leaching was detected from NZP. As compared to D-001, NZP showed more preferable adsorption toward both toxic metals from the background Ca(II) solution at greater levels. The synthetic Pb(II) or Cd(II) solution containing other ubiquitous metal ions was employed as the feeding influent for column adsorption, and the results indicated that the treatable volume of NZP is around 3-4 times that of D-001 before reaching the breakthrough point set according to the effluent discharge standard of China. With respect to Pb(II) removal from an acidic mining effluent, the treatable volume of NZP was 13 times higher than that of D-001. The exhausted NZP could be effectively regenerated by HNO3-Ca(NO3)2 binary solution for repeated use without any significant capacity loss. The superior performance of NZP was attributed to the Donnan membrane effect exerted by the host D-001 as well as the impregnated HZO nanoparticles of specific interaction toward toxic metals, as confirmed by the comparative isothermal adsorption and X-ray photoelectron spectroscopic study.