Sorption of dyes and Cu(II) ions from wastewater by sonochemically synthesized MnWO₄ and MnMoO₄ nanostructures

Abstract

MnWO₄ and MnMoO₄ nanoparticles have been synthesized using a facile sonochemical technique. The nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption–desorption measurements. The as-prepared spherical MnWO₄ and MnMoO₄ nanostructures have a high specific surface area and their excellent adsorbent properties to remove organic pollutants have been demonstrated for the first time. Complete removal of dyes like Rhodamine B and Methylene blue was possible within 2–10 minutes. The influences including initial pH, dosage of adsorbent and contact time have been researched in order to find the optimum adsorption conditions. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. MnWO4 also proved to be a good sorbent for Cu(II) ions. The kinetic modeling for Cu(II) sorption has been discussed. These studies showed that there is a possible application for the complete and fast removal of the organic dyes in the presence of inorganic cations using MnWO₄/MnMoO₄ sorbents. The thermal regeneration of the sorbents is possible and they show similar adsorption efficiency up to ten consecutive cycles. The sonochemically synthesized MnWO₄ and MnMoO₄ nanomaterials could serve as promising adsorbents for the removal of organic dyes, especially, cationic dye, and Cu(II) ions from polluted water.