Equilibrium, Kinetics, and Thermodynamics of Bovine Serum Albumin Adsorption on Single-Walled Carbon Nanotubes

Abstract

We investigated the equilibrium, kinetics, and thermodynamics of bovine serum albumin (BSA) adsorption on single-walled carbon nanotubes (SWNTs) from aqueous solutions with different pH and temperatures. We analyzed the experimental adsorption equilibrium and kinetic data to evaluate the adsorption characteristics of SWNTs for BSA. The results show that the effects of pH and temperature were important. Moreover, the adsorption isotherm data of BSA on SWNTs are consistent with the Langmuir and Freundlich models, while the kinetics can be expressed by the pseudo-first-order and the intraparticle diffusion rate models. The maximum protein adsorption capacity of SWNTs, which have a surface area of 191.2 m²/g, was found to be 609.8 mg g⁻¹ at pH 4 and 40°C, and this was the highest value obtained among our previous studies examined with various metal oxides. In addition, the zeta potential measurements were examined to understand the effects of charge density of the surface and the protein on the adsorption process. Thermodynamic analysis results indicate that the nature of adsorption changes with pH. SWNTs were found to be effective for BSA adsorption.

Keywords:

• Adsorption
• Adsorption isotherms
• Bovine serum albumin
• Protein
• Single-walled carbon nanotubes
• Zeta potential

Additional information

Funding

This research was supported by Bülent Ecevit University, Zonguldak, Turkey (Scientific Research Project 2010-13-02-09).