Ultrasound‐assisted enhanced and rapid uptake of anionic dyes from the binary system onto MnFe2O4/polyaniline nanocomposite at neutral pH

Abstract

Remediation of toxic dyes from an aqua matrix using novel nanocomposites as adsorbent is an attractive yet challenging task, especially when the adsorption process needs to be operated at near‐neutral solution pH. Recently, conducting polymer‐based novel nanocomposites have been studied widely for environmental remediation because of their high distinctive surface area, mesoporous nature, easy synthesis process, availability of the low‐cost monomer, and comprehensive range of functionality. This research deals with the fabrication and application of manganese ferrite and polyaniline nanocomposite (MnF‐PANI‐NC) for the ultrasound‐assisted adsorption of methyl red (MR) and congo red (CR) dye from binary dye solution at neutral pH. The X‐ray diffraction pattern of MnF‐PANI‐NC confirmed the successful impregnation of manganese ferrite onto polyaniline, and the field emission gun scanning electron microscopy and transmission electron microscopy images revealed the nanoscale formation of this composite. The saturation magnetization of ~20 emu/g endorses the easy magnetic separation of MnF‐PANI‐NC from dye solution. MnF‐PANI‐NC has revealed higher adsorptive affinity towards MR and CR dye concerning pure PANI and pure MnF nanoparticles at near‐neutral solution pH. Assimilation of ultrasound wavse in this adsorption procedure improved the mass transfer rate significantly, and within 6 min of reaction more than 95% of MR and CR dye removal was achieved. Ultrasound waves also enhanced the equilibrium dye uptake efficiency (more than 95%) of MnF‐PANI‐NC compared to the adsorption reaction by overhead stirring (40–50%) and shaking (40–60%) for both MR and CR dyes. Kinetic modeling of the experimental data revealed accurate fitting of the pseudo‐second‐order model in association with intraparticle diffusion. Binary dye adsorption onto MnF‐PANI‐NC obeyed the Langmuir isotherm model accurately, and maximum adsorption capacities of 294.12 and 317.46 mg/g were observed for MR and CR dyes, respectively.