Serendipitous discovery of super adsorbent properties of sonochemically synthesized nano BaWO₄

Abstract

The superior adsorbent properties of BaWO₄ nanostructures have been reported for the first time. Flower shaped aggregates (∼250 nm) of BaWO₄ nanoparticles, having an average size of ∼10–15 nm with a high surface area of ∼148.0 ± 0.2 m² g⁻¹, have been synthesized sonochemically and used for the adsorption of various cationic dyes from aqueous solutions. The sonochemically synthesized BaWO₄ have been characterized by scanning electron microscopy (SEM), selected area electron diffraction (SAED), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR). The adsorbent capacity of this tungstate is much higher than that reported for other nanomaterials like Fe₂O₃, MnO₂, WO₃, etc. Complete removal of dyes like rhodamine B and methylene blue was possible within a short time span of 10–15 minutes. The adsorption process was followed using UV-Visible spectroscopy, while the material before and after adsorption has been characterized using physicochemical and spectroscopic techniques. Various isotherms have been used to fit the data, and kinetic parameters were evaluated. Moreover, the adsorbed dyes could be desorbed completely from nanoparticle surfaces by annealing at moderate temperature and were found to be efficient for multicyclic use. Thus this sonochemically synthesized nano BaWO₄ has great significance in treatment of dye industry effluents as a promising adsorbent for cationic dyes from aqueous solution.