Electrochemical Characterization and Evaluation of the Analytical Potentialities of Glassy Carbon Electrodes Modified with Extracted Lignin from Black (Kraft) Liquor

Abstract

The electrochemical behavior of Kraft Lignin Glassy Carbon Modified electrodes, GCE-LIG, was studied. The modified electrode was prepared by recovering the glassy carbon surfaces with 10 μL of 1.0 and 0.01 g L -1 lignin in DMF. The polymeric film produced showed electrochemical activity due the quinone / hydroquinone (Q/HQ) redox couple produced from lignin by a mechanism involving an electrochemical oxidation step followed by a coupled chemical reaction. The GCE-LIG is stable at negative potentials up to -1.5 V in pH range of 2.0 to 8.0, but the lignin polymeric film is leached from the electrode surface at potentials higher than + 0.8 V. The modified electrodes showed resistive behavior, which increased with the film thickness. Another interesting characteristic of the GCE-LIG is its selectivity to coordination complexes since the electrochemical activity increases as function of the major complexes lability.