Polyvinylpolypyrrolidone-induced mesoporosity and surface modification in MoO₃/V₂O₅ nanocomposites for efficient and...

Water pollution from textile industries remains a significant environmental challenge due to the discharge of dye-containing effluents into aquatic systems. In the present study, a novel polyvinylpolypyrrolidone (PVPP)-functionalized MoO₃/V₂O₅ nanocomposite was synthesized through a wet chemical route and evaluated as an adsorbent for rapid dye removal from wastewater. The structural, morphological, and surface characteristics of the nanocomposite were investigated using X-ray diffraction, Williamson-Hall analysis, Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, zeta potential measurements, and Brunauer-Emmett-Teller and Barrett-Joyner-Halenda (BET-BJH) surface area analysis. The incorporation of PVPP resulted in enhanced surface properties, increased negative surface charge, and modified morphology. The synthesized nanocomposite exhibited a crystallite size of 15.3 nm, a lattice strain of 0.43%, and a zeta potential of -30 mV, favoring the adsorption of cationic dye molecules through electrostatic attraction. BET-BJH analysis revealed a mesoporous structure with a Type IV adsorption isotherm, a surface area of 25 m²/g, and an average pore diameter of 6.05 nm, providing numerous active adsorption sites. Adsorption studies demonstrated rapid removal of methylene blue, with the characteristic absorption peak at 664 nm disappearing completely within 5 min, corresponding to 99% removal efficiency. Industrial wastewater samples also showed complete elimination of dye-related absorption peaks after treatment. FTIR analysis of the dye-loaded adsorbent indicated the involvement of electrostatic interactions, hydrogen bonding, and n-π interactions. The nanocomposite maintained excellent reusability over six adsorption-desorption cycles without detectable leaching, indicating its suitability for wastewater treatment applications.