Surface modification of granular activated carbon by nitric acid for the enhancement of copper adsorption

Abstract

Concentrated nitric acid, a very powerful oxidizing agent, has been used for modifying surface of commercial grade carbon, filtrasorb- 400. Scavenging of copper ions from aqueous solutions onto both raw as well as modified granular activated carbon has been carried out. Equilibrium results show that surface modification increases the copper ion adsorption by 125% in comparison to that of raw granular activated carbon. FTIR spectra suggest that oxidation of granular activated carbon by nitric acid results in the formation of several functional groups at the carbon surface. The <i>p</i>H studies for both raw and oxidised granular activated carbon show that higher initial solution <i>p</i>H results in higher copper ion adsorption . The surface modification with nitric acid not only enhances the copper adsorption but also helps in regeneration of carbon.