Adsorption of nitrate ions onto activated carbon prepared from rice husk by NaOH activation

Abstract

Precursor was prepared from rice husk under different carbonization temperatures. Then, activated carbon (AC) was synthesized by NaOH activation. The specific surface area of carbon increased with temperature rise up to 600°C, but decreased rapidly over 600°C. So, the AC obtained at 600°C possessed the outstanding surface area of 2,802 m²/g. And, its adsorption activity of nitrate was carried out at initial concentration of 50–400 mg/L. The results showed that the maximum adsorption capacity and removal percentage of were 70.2 mg/g and 70.6%, respectively. Besides, the experimental data were evaluated by Langmuir, Freundlich, and Redlich–Peterson isotherms. In kinetic studies, it was observed that the results were well explained by the pseudo second-order model. In addition, the Gibbs free energy change of −17.0 kJ/mol indicated that the adsorption process was spontaneous.

Keywords:

• Activated carbon
• Rice husk
• Nitrate
• Adsorption

Acknowledgments

This research was supported by the projects of International Cooperation of Science and Technology Ministry of China (No. 2005DFBA028). The authors acknowledge Mr. Chen Hao and Mrs. Zhou Jing, Component Engineering, Askey Technology (Jiangsu). Ltd., China, who performed the correction for language.