Activated Carbon Produced from Rice Husk by NaOH and KOH Activation and its Adsorption in Methylene Blue

Abstract

Sodium hydroxide (NaOH) and potassium hydroxide (KOH) rice husk activated carbon were prepared using a method of two-step comprising of carbonisation and activation processes. These adsorbent samples were used to remove methylene blue (MB) solution. Some chemical and physical characteristics of adsorbents were determined using proximate analysis, Brunauer–Emmett–Teller surface area (BET) and scanning electron microscope (SEM) before  carrying out the MB adsorption experiments. The analyses of adsorption kinetics were performed at several conditions of pH, MB concentration and temperature to investigate the efficiency of adsorption of the samples on the MB solution. The analyses of adsorption kinetics related to the pseudo-second-order model. The capacity of adsorption of the KOH rice husk activated carbon (RHACK) on MB achieved a maximum of adsorption at 317.24 mg/g as compared to the NaOH rice husk activated carbon (RHACNa) at 210.90 mg/g. The model of intraparticle diffusion showed that the process of adsorption of RHACK and RHACNa against MB included the diffusion of MB molecules and external mass transfer to the surface of adsorbents.