Preparation and Characterization Polypyrrole/Humic Acid Composite Electrode for Metal ion Extraction

Redox and acid base properties of soil humic substances were studied. Phenolic groups predominated over the carboxylic groups. The oxidation capacity of humic acids (HA) show values from 1.7 and 2.2 molc kg-1 at pH 7.0 and pH 9.0, respectively. A relationship between redox activity and both pH and humic acid content of carboxylic groups was observed. The formal potential () presented values of 1.50 V, demonstrating the oxidizing nature of the studied HAs. Based on these results, HA from Diguillin (D) soil was considered for the design of an electrode in the presence of polypyrrole (PPy). Consequently, a paraffin-impregnated graphite electrode (PIGE) modified with HA-D/Ppy was tested in copper solutions (Cu (II), CuCl42-). The results showed that the device worked properly as analyte extractant, being 50% more efficient than the same electrode in the absence of HA-D (PIGE/PPy).