Efficient Selective Sorption of Cationic Organic Pollutant from Water and Its Photocatalytic Degradation by AlVO₄/g-C₃N₄ Nanocomposite.

This study reports the synthesis, characterization and water remediation application of novel AlVO₄/g-C₃N₄ nanocomposites. The nanocomposite has been synthesized by a low temperature solid-state reaction using graphitic carbon nitride (g-C₃N₄) obtained via calcination of melamine and AlVO₄ prepared via assisted sonochemical technique. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), and the N₂ gas adsorption Brunauer-Emmett-Teller (BET) method has been used to characterize the pristine and composite samples. AlVO₄ and g-C₃N₄ interact with each other forming a hybrid composite, which shows excellent ability for selective sorption of cationic MB (methylene blue) dye from wastewater. The initial dye concentration, pH and amount of sorbent has been varied and their effect on the adsorption process has been analysed. The photocatalytic efficiency of the MB dye adsorbed pristine g-C₃N₄, AlVO₄:g-C₃N₄ (1:3) and AlVO₄:g-C₃N₄ (1:1) composite has been tested under visible light. With increased proportion of AlVO₄ in the samples, the photocatalytic efficiency improved and the best photodegradation has been observed for the AlVO₄:g-C₃N₄ (1:1) sample. Photoluminescence (PL) studies, photocurrent response measurements and electrochemical impedance spectroscopy (EIS) indicates enhanced separation of the photogenerated electron/hole pairs leading to effective degradation of the MB dye solution in case of the AlVO₄:g-C₃N₄ (1:1) composite sample. The photocatalytic mechanism has been elucidated and it could be inferred that photogenerated holes and superoxide anion radicals play a major role in the photocatalysis process.