Process optimization and modeling of Pb(II) ions adsorption on chitosan-conjugated magnetite nano-biocomposite using...

This study aimed to investigate the performance of a magnetic nano-biocomposite, chitosan conjugated magnetite nanoparticle (CH-MNP), for the removal of lead ions. The magnetite nanoparticles were synthesized through a controlled co-precipitation technique and were stabilized with citric acid. Subsequently, they were covalently bonded to chitosan via carbodiimide chemistry using EDAC/NHS activation. One of the notable advantages of this nano-biocomposite is its chemical conjugation, which does not have the weakness of the ultimate chitosan detachment of a physical bond and makes it an encouraging candidate for magnetic separation with no secondary waste production. The CH-MNPs had a diameter of ∼10 nm, with a saturation magnetization of 76.01 emu/g ensuring a superparamagnetic property. The response surface methodology (RSM) with a central composite design (CCD) framework was used for optimizing the adsorption process. The optimum conditions to achieve 92.15% of Pb(II) removal were found to be at a pH of 6.1 with the nano-adsorbent concentration of 1.04 g/L and a contact time of 59.92 min. Our adsorption isotherm data were fitted well with the Langmuir adsorption isotherm model, and the equilibrium data followed the pseudo-second-order kinetics and intraparticle diffusion kinetic model. The maximum Langmuir Pb(II) adsorption capacity was calculated to be 192.308 mg/g. These results suggest that the proposed synthetic nano-biocomposite is quite an ideal nano-adsorbent for Pb(II) removal in wastewater treatment technology.