Modification of a commercial activated carbon for metal adsorption by several approaches

Abstract

It has been widely recognized that metal removal by activated carbon adsorption is due to the surface complex formation between the metal ions and the acidic surface functional groups. Improvement of Filtrasorb 200 by using several modification approaches is investigated in this study. The carbon was first modified by nitric acid or by citric acid and subsequently by sodium hydroxide. It was found that modification slightly altered the surface area of the activated carbon. Kinetic study showed that the modifications greatly decreased the adsorption equilibrium time. In addition, the metal uptake was dramatically increased. Maximum adsorption capacities (qmax) determined by the Langmuir isotherm equation were 0.124, 0.208 and 0.244 mmol/gm for unmodified, modified by citric acid and nitric acid, respectively. Sodium hydroxide modification resulted in faster adsorption kinetics, but slightly decrease the maximum adsorption capacity. The effect of solution pH on metal ion adsorption was also discussed in this paper. © 2008 - Kalpana Corporation.