Functionalization of activated carbons by HNO3 treatment: Influence of phosphorus surface groups

Influence of phosphorus on functionalization of activated carbons with nitric acid has been reviewed in this study. Results indicate that during treatment with nitric acid, phosphorus-containing carbons seem to graft more surface nitrogen, particularly as nitro groups, than those without phosphorus, where the nitrogen is found in lower oxidation state. A reaction pathway has been proposed to clarify the oxidation/nitration mechanism of phosphorus-containing carbons. The model consists of three independent mechanisms occurring simultaneously, with each one involving different phosphorus species present in the activated carbons.