Exploring the impact of oxidant ratio on polypyrrole properties: electrical, optical, and adsorption behaviour.

Abstract

Synthetic dyes are among the common pollutants in the ecosystem. In the present study, polypyrrole (PPy) was prepared and subsequently assessed for the removal of methylene blue (MB) and methyl orange (MO) from synthetic solution. PPy powders were successfully synthesized through chemical oxidative polymerization, utilizing varying molar ratios of ferric chloride (FeCl3) to pyrrole (Py) monomer. The effects of FeCl3:Py molar ratios ranging from 1:1 to 4:1 were investigated in terms of electrical and optical properties, as well as organic dye adsorption performance. The electrical conductivity reached its maximum value of 3.42 × 10−2 S/cm at the optimum FeCl3:Py molar ratio of 2:1 (P2), while it displayed the lowest optical bandgap energy of 3.72 eV. Beyond this molar ratio, both electrical conductivity and optical bandgap energy exhibited a declining trend. Additionally, the adsorption behavior of PPy samples with different FeCl3:Py molar ratio was indicated that the P2 sample exhibited the highest adsorption capacity for MO, reaching 84.65 mg.g−1 after 120 min, while its adsorption capacity for MB was 73.84 mg.g−1. The phase characterization using XRD analysis revealed the amorphous nature of the PPy powders, and FTIR results exhibited minor changes in peak intensity with increasing FeCl3:Py molar ratio. The synthesized PPy samples exhibited an average particle size ranging from 0.344 to 0.703 µm and a BET surface area of 2.27–3.56 m2.g−1. Besides, morphological analysis unveiled the presence of globular particles with a cauliflower-like structure, varying in size. The findings of this study hold significant implications for the fabrication of electronic devices based on PPy. Furthermore, the synthesized PPy samples exhibited promising adsorption capabilities for the removal of dyes, 84.65 mg/g for MO and 73.84 mg/g for MB dyes after 120 min, emphasizing their potential utility in environmental remediation applications.