Carbon nanocages as heavy metal ion adsorbents

Abstract

Heavy metal ion contamination in drinking water poses a major risk to human health, whilst contamination in wastewater streams can cause damage to the wider environment. In this study carbon nanocages, synthesised using a supercritical fluid deposition method, were examined as adsorbents of Pb 2+ ions from aqueous solutions. Through careful selection of the catalyst and the carbon deposition temperature and pressure, high yields of nanocages with surface areas up to 1175 m 2 g −1 were synthesised. These high surface area materials were subsequently tested for their ability to absorb Pb 2+ ions, as a function of pH, from simulated wastewater. The nanocages were found to be effective at removing the Pb 2+ ions at levels of 11.1 mg g −1, compared to 7.6 mg g −1 for commercially available activated carbon. The kinetics of metal ion adsorption by the nanocages and activated carbon can be described by a pseudo-second-order kinetics model, with a rate coefficient ( k 2) of 4.8 × 10 2 g mg −1 min −1.