Preparation of Micropore-Containing Adsorbents from Kenaf Fibers and Their Use in Mercury Removal from Aqueous Solution

Abstract

Here, a number of activated carbon fibers (ACFs) prepared from kenaf natural fibers (KNFs) by chemical activation with KOH under different operation conditions have been used as adsorbents for the removal of mercury from aqueous solutions. Samples were characterized by N2 adsorption at 77 K, mercury porosimetry, scanning electronic microscopy (SEM), and FT-IR spectroscopy. The adsorption of mercury at 25°C without pH adjustment from an aqueous solution was evaluated from both kinetic and equilibrium standpoints. It was found that the activation conditions during the preparation of ACFs (i.e., impregnation ratios and activation temperatures) had a strong influence on the porosity of the resultant samples and, therefore, on their mercury adsorption capacity. The sample prepared at 800°C using an impregnation ratio of 3:1 (named K3-800) presented the maximum Langmuir adsorption capacity (10.53 mg/g). This sample showed a specific surface area of 881 m2/g, a micropore volume of 0.60 cm3/g, and the highest total pore volume (2.69 cm3/g).