Adsorption-Assisted Photocatalytic Degradation of Anionic Direct Yellow-50 and Cationic Methylene Blue Dyes by Chemically Synthesized Poly(1,5-diaminoanthraquinone)

The conductive polymer poly(1,5 diaminoanthraquinone) (PDAAQ) has been synthesized by chemical oxidative polymerization using ammonium peroxydisulfate (APS) as an oxidant and perchloric acid (HClO ₄ ) as an initiator in the presence of acetonitrile (ACN) polymerization medium. The characterization of PDAAQ was completed via X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible absorbance spectroscopy (UV-vis), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDX), Brunauer–Emmett–Teller analysis (BET) and four-point probe electrical conductivity measurements. PDAAQ with a band gap of 1.28 eV and an electrical conductivity of 1.23 S/cm was successfully synthesized. The adsorption-assisted photocatalytic performance of PDAAQ has been investigated in cationic methylene blue (MB), and an anionic direct yellow (DY) dye under the visible irradiation. For both MB and DY dyes, the reactions were determined to be pseudo-first order equations for the adsorption-assisted photocatalytic process. The effect of polymerization medium, oxidant type, polymerization time and monomer oxidant ratio on adsorption assisted photocatalytic degradation of MB was investigated. The synthesized PDAAQ polymer has excellent photocatalytic performance as a photocatalyst for degradation of MB and DY. 10 µM MB and DY dyes were completely degraded in only 6 and 8 min under visible light illumination using PDAAQ polymer by adsorption-assisted photocatalysis mechanism. Also, the photocatalytic dye degradation performance of PDAAQ was investigated for degradation of synthetic wastewater (SWW) under visible light. PDAAQ polymer can be used as an effective photocatalyst in photocatalytic applications due to its superior and promising performance for the degradation of model dyes and synthetic wastewater.