Abstract: Because of the chemical reaction between Cr(VI) ions and glutathione, the peak reduction current of Cr(VI) ions decreases while adding glutathione (GSH) into a K₂Cr₂O₇/H₂SO₄ solution. Thus the concentration of GSH can be detected indirectly by differential pulse voltammetry (DPV) analysis. This electrochemical indirect method was used to study the adsorption of GSH on multi-walled carbon nanotubes (MWCNTs) and activated carbon (AC), and can be used to determine the equilibrium relationship between GSH adsorption and its concentration. Unlike the result obtained from the active carbon, GSH adsorption on MWCNTs agrees better with that predicted by the Freundlich equation compared to that predicted by the Langmuir equation. The morphologies of MWCNTs and activated carbon were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The abundance of aggregated pores in MWCNTs is beneficial for the diffusion and adsorption of small GSH molecules, suggesting that MWCNTs could be developed as an adsorbent for small molecular substances.

Key words: Electrochemical indirect measurement, Glutathione, MWCNTs, Activated carbon, Adsorption mechanism