Iron chlorophyll-a as biomimic catalyst for the green synthesis of polyaniline nanostructures: Evaluation, characterization and optimization.

Abstract

In this paper reported is the method of producing polyaniline (PANI) in a green and sustainable way. This work follows the attempt to find an environmentally benign way of synthesizing PANI. The green innovation has been using the enzyme horseradish peroxidase, Laccase and hemoglobin, but being enzymes they lose the catalytic activities in the region where best conducting PANI is formed. To overcome the limitation of the biocatalyst, the synthetic biomimic catalysts have been reported. The synthetic biomimic catalysts have involved the creation of tetra pyrrole porphyrin and chelated with metals and evaluated for their catalytic activities for the synthesis of PANI. Yet nature synthesizes the porphyrins in the clean, green and sustainable way, it was from this background that this research was done in modifying the chlorophyll-a porphyrin by chelating it with iron (III) and catalytic activities be evaluated.The synthesis of PANI was done in 1.0 M hydrochloric acid, 0.2 M sodium lauryl sulfate was used as a surfactant, and activated with hydrogen peroxide 0.1 M. The polymerization process was monitored for in-situ absorbance at 650 nm wavelength and time course graph generated. The time of entering a steady state showed dependence on the concentration of iron-chlorophyll-a biomimic catalyst used.The PANI formed was characterized with UV–Visible and FT-IR spectroscopy for optical properties, the peaks at 320 nm, 420 nm and 780 nm in UV–visible showing π-π* transitions and polaron transitions. The characteristic peaks too for IR were observed.The morphological evaluation of the PANI by atomic force microscope showed uniformly distributed elliptical shaped polymer. The electrical characteristic showed the PANI was conducting and conductivity of 0.142 S/cm was recorded.Polyaniline could indeed be synthesized when chlorophyll-a porphyrin chelated with iron (III) is used as a biomimic catalyst, the optimal concentration of 1.2 mM established, the initiator/monomer ratio needed to 2.5 for maximum PANI yield of 89.0%.