Tests for Evaluating the Efficacy of Phosphoric Acid Activated Charcoals from Two Biomasses

Abstract

Good quality activated charcoals were prepared from areca nutshell and coconut shell using phosphoric acid as a chemical activating agent at 400oC. Physico-chemical properties like iodine number, methylene blue number, and surface area of two activated charcoals were measured to assess the porous nature. A special test called acetic acid number was devised to understand the quality of functional groups on charcoal surfaces. Proximate analysis and physical properties of the two activated charcoals closely matched those of a commercial sample, confirming the good quality of samples prepared in the laboratory. Adsorption of isolated caramel from waste stream obeyed Freundlich isotherm, and the data could be explained based on the physisorption of large size molecules on the walls of mesoporous solid surface. Adsorption of methylene blue involving Coulombic attraction towards the areca nut shell-derived activated charcoal could be predicted and confirmed based on the acetic acid number for the first time.

Keywords

• activated charcoal, areca nutshell, coconut shell, phosphoric acid activation, methylene blue adsorption, caramel adsorption, acetic acid number