V-Doped Starch/Graphitic-Carbon Nitride Composite for Enhanced Pollution Degradation through Response Surface Methodology: The Study of Photocatalytic and Adsorption Process

The V-doped starch/graphitic carbon nitride was synthesized for the degradation of organic pollutants. This novel photocatalyst was characterized by various techniques including Fourier Transform InfraRed (FT-IR) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffractometer (XRD), Photoluminescence (PL) spectroscopy, Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. Based on the Central Composite Designs-Response Surface Methodology (CCD-RSM) design, 50 full experiments were done including pH (7.8-9.8), adsorbent dose (0.01-0.1 g), MB concentration (2-12 ppm), time (30-240 min), and temperature (15-45 °C) for the methylene blue removal by V-doped starch/graphitic carbon nitride, and the best removal yield (90.8 %) was obtained at pH=8.33, 0.08 g adsorbent dose, 12 ppm of MB concentration, 215 min, and 15 °C. Further, the interaction of adsorption parameters was considered, and the Freundlich and pseudo-second-order were shown as the best adsorption models. After the adsorption process, the photocatalytic degradation of MB was conducted under UV irradiation with high yield (92 %), and the trapping experiments confirmed the photocatalytic degradation. As a result, the V-doped starch/graphitic carbon nitride can be employed for the adsorption and photocatalytic activities for the removal of organic pollutants from aqueous solution.