Adsorption of heavy metals (Cu 2+ and Zn 2+ ) on novel bifunctional ordered mesoporous silica: Optimization by response surface methodology

Abstract

Abstract In order to develop new technologies in adsorption-based water treatment systems, the main objective of this research is the removal of copper and zinc heavy metals from aqueous solution using modified biocompatible silica magnetic nanoadsorbents. In this regard, the magnetic SBA-15 based Chitosan composite modified with amine groups (Fe2O3@SBA-15 − CS − APTMS), with different weight percentages, were synthesized and further characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and nitrogen adsorption/desorption analysis. The adsorption performance of Fe2O3@SBA-15 − CS − APTMS (3 mL) for copper and zinc removal from aqueous solution was studied in a batch system using response surface methodology (RSM) design of experiment. All the prepared adsorbents were tested under the obtained optimum operational parameters and their adsorptive behavior was compared. In order to investigate the adsorption rate and maximum adsorption capacity, the experimental data were fitted to Langmuir, Freundlich, Temkin, Redlich–Peterson and Sips isotherms and pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models. In addition, analysis of adsorption efficiency at different temperatures revealed the thermodynamic aspects of adsorption such as the variations in Gibbs free energy (ΔG0), standard enthalpy (ΔH0) and standard entropy (ΔS0). The obtained maximum adsorption capacities of Fe2O3@SBA-15 − CS − APTMS (6 mL) at 313 K for copper and zinc were 107.30 mg/g and 100.47 mg/g, respectively.