Adsorption kinetics, thermodynamics and desorption of natural dissolved organic matter by multiwalled carbon nanotubes

Abstract

Multiwalled carbon nanotubes (CNTs) were thermally treated and were employed as adsorbents to study their adsorption kinetics and thermodynamics of natural dissolved organic matter (NDOM) from aqueous solutions. The adsorption kinetics follows the first-order rate law while the adsorption thermodynamics indicates the exothermic and spontaneous nature. A comparative study on the adsorption/desorption properties of NDOM between CNTs and granular activated carbon (GAC) was also conducted and revealed that the CNTs possess more NDOM adsorption capacities and show less weight loss through 10 cycles of water treatment and reactivation than the GAC. This suggests that the CNTs are promising NDOM adsorbents for preventing the microbiological degradation of drinking water quality as well as the formation of disinfection by products in water treatment.

Keywords:

• Multiwalled carbon nanotubes
• adsorption/desorption properties
• natural dissolved organic matter
• granular activated carbon

Acknowledgments

This work was supported by the National Science Council, Taiwan, under a contract no. NSC94-2211-E-005-038.