Fabrication of PANI@Fe–Mn–Zr hybrid material and assessments in sono-assisted adsorption of methyl red dye: Uptake performance and response surface optimization

Abstract

In recent decades, industrial wastewater discharge containing toxic or hazardous manufactured dyes has risen tremendously, creating a serious environmental threat. A new hybrid adsorbent, PANI@Fe–Mn–Zr synthesized by mixing Fe–Mn–Zr metal oxide composite with polyaniline (PANI), was used to study methyl red (MR) dye removal from aqueous solution. The adsorption process was observed to be influenced by the sonication time, dose of PANI@Fe–Mn–Zr, and initial concentration of MR dye. At an initial MR dye concentration of 25 mg/L, 0.25 g/L of PANI@Fe–Mn–Zr dose, 15 min of sonication, and pH 7.0, the maximum MR dye adsorption efficiency of 90.34% was achieved. Kinetic analysis was performed using five different kinetic models, which shows that the pseudo-second-order kinetic model had the best fit among the five models. The Langmuir isotherm best fits the adsorption experiments at pH 7.0, yielding a significant MR dye uptake capacity of 434.78 mgg−1. The most significant adsorption mechanisms that have been observed in uptake of MR dye onto PANI@Fe–Mn–Zr were electrostatic attraction, π-π bond interactions and hydrogen bonding. Response surface optimization study was performed for optimizing the experimental conditions from which maximum dye removal of 98.19% was obtained at contact time of 12 min, initial MR dye concentration of 15 mg/L and PANI@Fe–Mn–Zr dose of 0.4 g/L. Use of real wastewater and water samples suggest that there is only 6–19% reduction in the dye removal efficiency as compared to the blank or controlled experiments conducted with deionized water.