WITHDRAWN: Synthesis and Characterization of Pendant N,N-dimethylaminobenzaldehyde-functionalized Chitosan Schiff Base Composite (CS@MABA) As a New Sorbent for Removal of Pb(II) Ions from Aqueous Media

In this work, new pendant N,N-dimethylaminobenzaldehyde-functionalized chitosan Schiff base composite (CS@MABA) was prepared from the simple and convenient condensation reaction between chitosan (CS) and N,N-dimethylaminobenzaldehyde (MABA) in ethanol-glacial acetic acid (1:1 v/v) and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscope (SEM). The as-prepared composite CS@MABA was applied for the removal of Pb(II) ions, due to the presence of imine, hydroxyl and phenyl groups, and the effects of important parameters such as solution pH, contact time and sorbent dosage on the removal percentage and adsorption capacity were investigated and discussed. The optimum conditions were found to be at pH 5, adsorbent dosage of 0.1 g, Pb(II) concentration of 50 mg/L and contact time of 60 min. The maximum Pb(II) removal percentage was found to be 94.28 % with the high adsorption capacity of 165 mg/g. The adsorption capacity of CS@MABA is remain 87 % after 5 adsorption-desorption cycles. The adsorption kinetic and isotherm studies indicated that the Pb(II) removal by CS@MABA follows a pseudo-first order and Langmuir models, respectively. Compared to similar compounds, the synthesized CS@MABA composite has shown a relatively high yield for removing Pb(II) ions. According to these results, the CS@MABA suggested for the sorption of other heavy metals.