Preparation of polypyrrole@CoFe2O4 nanocomposite for the adsorptive removal of Arsenic(III): kinetic and mechanistic analysis

Abstract

Water contaminants represent a significant global challenge that impacts the environment. The dispersal of production waste significantly impacts this problem. By in-situ polymerizing pyrrole on CoFe₂O₄ nanoparticles, a polypyrrole-coated cobalt ferrite (PPy@CoFe₂O₄) magnetic nanosorbent is synthesized to achieve effective removal of As(III). XRD data corroborated the findings of the SEM examination, which showed spherical nanoparticles with diameters of about 50 nm. Spinel ferrite production was suggested by the FTIR spectra, which showed clear peaks in the 400–600 cm^− 1 region, confirming the evidence of M–O bonds. The optimal removal of As(III) (99%) occurred at a pH of 6.0 to 7.0, with an adsorbent dosage of 40 mg. PPy/CoFe₂O₄ demonstrates a maximal monolayer adsorption capacity of 201.4 mg g^⁻1 under optimum conditions (330 K temperature, 40.0 mg adsorbent dose, and pH 6.0). Adsorption followed a pseudo-second-order kinetic model with an equilibrium time of 210 min. The adsorption isotherms were accurately represented by the Langmuir model. The removal efficiency was still higher than 94% following the five adsorption-desorption cycles. The adsorption of As(III) by PPy@CoFe₂O₄ is strongly influenced by pH of the medium. Electrostatic interaction is likely the main mechanism of As(III) adsorption onto PPy/CoFe₂O₄. The adsorption of As(III) onto PPy/CoFe₂O₄ takes place spontaneously, as indicated by a negative ΔG°. The results indicate that the PPy/CoFe₂O₄ composite functions as a highly efficient adsorbent, showcasing extensive applicability in the treatment of wastewater contaminated with heavy metal ions.