Rapid removal of Pb(II) from aqueous solution using branched polyethylenimine enhanced magnetic carboxymethyl chitosan optimized with response surface methodology

In this study, branched polyethylenimine (PEI) enhanced magnetic carboxymethyl chitosan (MCMC-PEI) was synthesized and applied as adsorbent for the rapid removal of Pb(II) from aqueous solution. The successful synthesis of the adsorbent was proved by scanning electron microscope (SEM), Fourier transform infrared spectrum (FTIR) and X-ray powder diffraction (XRD). Simultaneously, the effect of the parameters such as initial concentration, adsorbent mass and pH of the solution on the removal of Pb(II) was studied by using response surface methodology (RSM). And central composite design (CCD), which is a widely used form of RSM, was employed in the experimental design procedure. The adsorption results revealed that the adsorption process could reach equilibrium rapidly within 10 min. Furthermore, the adsorption kinetic data could be well described by pseudo-second order model. The maximum adsorption capacity was 124.0 mg/g according to the Langmuir-Freundlich model, which fitted the adsorption isotherm of Pb(II) better than Langmuir model and Freundlich model, respectively. Thermodynamic studies (Δ G  < 0, Δ H  < 0, Δ S  > 0) implied a spontaneous and exothermic process in nature. Meanwhile, the fabricated adsorbent exhibited excellent reusability. Therefore, the excellent adsorption property of MCMC-PEI made it a promising application in water treatment.