Full Length Research Paper

Equilibrium studies and kinetics mechanism for the removal of basic and reactive dyes in both single and binary systems using EDTA modified rice husk

Siew-Teng Ong¹*, Weng-Nam Lee², Pei-Sin Keng³, Siew-Ling Lee⁴, Yung-Tse Hung⁵ and Sie-Tiong Ha¹

¹Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia.

²Department of Science, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, Setapak 53300 Kuala Lumpur, Malaysia.

³ Department of Pharmaceutical Chemistry, International Medical University,

No.126, Jalan 19/155B, Bukit Jalil, 57000 Kuala Lumpur, Malaysia.

⁴Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 Skudai, Johor Malaysia.

⁵Department of Civil and Environmental Engineering, Cleveland State University, Cleveland, Ohio, USA.

*Corresponding author. E-mail: ongst@utar.edu.my, st_kenji@yahoo.com. Fax: 605-4667449

Accepted 25 February, 2010

   Abstract

The potential of using ethylenediamine tetraacetic acid modified rice husk (ERH) to remove different types of dyes, namely basic and reactive dyes were studied. Sorption characteristic of ERH showed that it was pH dependent. The kinetics of sorption for both dyes was rapid within the first 60 min regardless of its initial concentration. Using the pseudo-second order kinetics model, the predicted uptakes of Methylene Blue (MB) and Reactive Orange 16 (RO16) agreed closely with experimental values obtained. Three isotherm models were used to fit with equilibrium data, namely Langmuir, Freundlich and BET models. It was found that the equilibrium fitted well in Freundlich isotherm with higher regression coefficient value, R². Thermodynamic parameters showed that the sorption of process of MB and RO16 are exothermic and endothermic, respectively. Decrease in sorbent particle size led to an increase in the sorption of dyes. The study revealed that ERH is suitable to use as a single sorbent to remove both MB and RO16 in all systems.

Key words: EDTA modified rice husk, adsorption, binary mixture system, methylene blue, reactive orange 16.