Lead removal from water - dependence on the form of carbon and surface functionalization.

We have investigated lead adsorption on different forms of nanostructured carbon, namely multiwall carbon nanotubes (MWCNT) and reduced graphene oxide (RGO) functionalized with different functional groups (hydroxyl, carboxyl, and amino groups). We found that the same functional group does not result in the same performance trends for different nanostructured carbons. Drastically different behavior was observed for the amino-group functionalization, where a significant improvement is observed for MWCNT, while worse performance compared to non-functionalized material is obtained for RGO. On the other hand, hydroxyl and carboxyl group functionalization improves the lead adsorption regardless of the form of carbon. The best performing RGO sample, namely carboxyl group functionalized one, exhibited maximum lead adsorption capacity of 298.49 mg g which was significantly higher than that of the best performing MWCNT sample (amino-functionalized MWCNT, 58.547 mg g).