Characterization of Kaolin Glassy Carbon Modified Electrodes: Preconcentration of 2‐Chlorophenol

AbstractIn this paper we describe the use of two kaolin‐type aluminosilicate clays, a commercial ceramic‐grade kaolin (K) and a natural kaolin from mines in Bolívar State Venezuela (K‐Ve), for the preparation of film‐based clay‐modified glassy carbon electrodes. We examine their behavior during the preconcentration and subsequent anodic oxidation of 2‐chlorophenol. Kaolin samples were used as raw materials and modified with cationic surfactant, cetyltrimethylammonium bromide (CTAB) or nonionic surfactant, octylphenoxypolyethoxyethanol (TX100). The electrode polishing was the key step to produce stable films. 2‐Chlorophenol electrooxidation is favored by the presence of the surfactants in the film. The X‐ray patterns show that the kaolin K‐Ve includes quartz as nonclay mineral, while the kaolin K showed only diffraction peaks characteristic of kaolinite phase. This may be why the TX100/K‐Ve/GC electrode adsorbs more 2‐CPh than the TX100/K/GC electrode. On the other hand, analysis of the limiting currents obtained from hydrodynamic techniques indicated that the permeability of TX100/kaolin films is greater than that of CTAB/kaolin films. The TX100/K‐Ve/GC electrode showed excellent stability. A linear response range from 0.01mgL−1 up to 0.1 mg L−1 with a detection limit of 0.0016 mg L−1 was observed in the optimized conditions.