Synthesis and Characterization of Polyaniline Using Potassium 3-(Trifluoromethyl)phenyltrifluoroborate and Ni(II) Ions: Photocatalytic Degradation of Methylene Blue under UV Light

In this study, three polyaniline (PANI) samples were synthesized under different experimental conditions to investigate the effects of potassium 3-(trifluoromethyl)phenyltrifluoroborate (PTMPB) and Ni(II) ions on their physicochemical and photocatalytic properties. To the best of our knowledge, PTMPB and Ni(II) were used for the first time in PANI synthesis as a dopant and a Lewis acid, respectively. Three different PANI samples were synthesized: PANI A in the presence of aniline, HCl, and the oxidant H₅IO₆; PANI B in the presence of aniline, HCl, PTMPB, and the oxidant; and PANI C in the presence of aniline, PTMPB, Ni(II) ions, and the oxidant. The synthesized polymers were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrical conductivity measurements. The characterization results revealed that the synthesis conditions significantly affected the morphology, crystallinity, thermal behavior, and electrical conductivity of the polymers. The photocatalytic activities of the polymers were evaluated through the degradation of methylene blue (MB) under UV irradiation. After 300 min, the degradation efficiencies of PANI A, PANI B, and PANI C were found to be 72.02%, 87.55%, and 94.91%, respectively. Kinetic analysis showed that the degradation process was consistent with the pseudo-first-order kinetic model, with apparent rate constants of 0.00194, 0.00265, and 0.00576 min⁻¹ for PANI A, PANI B, and PANI C, respectively. The results indicate that the incorporation of PTMPB and Ni(II) ions is an effective strategy for enhancing the performance of PANI in the degradation of MB under UV irradiation.