Removal of hexavalent chromium ions and Acid Red 18 by superparamagnetic CoFe2O4/polyaniline nanocomposites under external ultrasonic fields

Abstract

In the present research, the adsorptive removal of dye and Cr(VI) ions from the aquatic solutions have been investigated using fabricated magnetic cobalt ferrite (CoFe 2 O 4 ) nanoparticles coated by polyaniline (CoFe 2 O 4 /PANI) via a hydrothermal and in-situ polymerization method. Magnetic composite of CoFe 2 O 4 /PANI was characterized by FE-SEM, EDS, XRD, VSM, FTIR, BET, BJH, and element mapping. The resulting composite was applied for the removal of hexavalent chromium (Cr(VI)) ions and Acid Red 18 (AR18) anionic azo dye individually from an aqueous solution under external ultrasonic fields. The removal efficiency of Cr(VI) ions and AR18 dye were studied as functions of the various parameters like time sonication, amount of adsorbent, initial concentration of Cr(VI) or AR18, and solution pH. The adsorption behavior and the equilibrium data were represented by the Langmuir isotherm model. The maximum monolayer adsorption capacity by as-prepared composite reached 103.11 mg g −1 and 172.41 mg g −1 for Cr(VI) ions and AR18 dye, respectively. The thermodynamic analysis demonstrated that these adsorption processes were spontaneous in nature and endothermic. The magnetically recyclable composite indicated suitable reusability during cyclic adsorption. The increase in ionic strength causes a decrease in the adsorption of Cr(VI) and AR18. This study may provide a promising magnetic composite for the efficient removal of inorganic and organic anions from the water environment. • Application of magnetic CoFe 2 O 4 /PANI for ultrasound assisted adsorption of Cr(VI) ions and AR18 dye. • Desirability function approach combined with CCD method was used to optimize the process variables. • CoFe 2 O 4 /PANI is superior to CoFe 2 O 4 for Cr(VI) ions and AR18 dye adsorption. • The maximum adsorption capacity for Cr(VI) ions and AR18 dye reached 103.11 mg g −1 and 172.41 mg g −1 , respectively. • Reusability tests indicated suitable regenerability of CoFe 2 O 4 /PANI.