Activity of free peroxidases, hematin, magnetite-supported peroxidases and magnetite-supported hematin in the aniline elimination from water-UV–vis analysis

This manuscript presents the UV–vis study of the aniline elimination by polymerization using peroxidases from different sources and hematin, free and supported. The use of magnetite-supported hematin has potential in the implementation of aniline elimination by polymerization in acidic media at pH 4. The temperature must be selected between 45 and 65 °C. Crude preparations of Pleurotus sajor caju (PSC) are an alternative to purified Horseradish peroxidase (HRP) as the catalyst of the reaction. Pernigraniline is the main species found in the reaction media after aniline elimination procedure. Supported oxidoreductases are active biocatalysts and conversion of aniline in the 30–90% range can be obtained, depending on the catalyst. The UV–vis spectra show bands corresponding to base and protoned (blue and purple-deep red) pernigraniline, a contribution of quinoid species at 480 nm and a minor contribution of base blue emeraldine and another oxidation intermediate states between pernigraniline and emeraldine. At selected conditions, the recovered solid showed greenish/reddish coloration. The goal is the precipitation of the aniline as polyaniline. Supported biocatalysts were less active than free enzymes.