The Preparation Of Amino-modified Superparamagnetic Nanoparticles And Their Adsorption To Heavy Metal Ions In Wastewater

Magnetic nano-materials exhibit unique advantages because of their characteristics of both magnetic materials and nano-materials which have been attention by many researchers.It is made into an adsorbent material to treat the pollutants in the sewage.And after the adsorption completed,it can also be separated from the water using an external magnetic field.In order to further increase the adsorption performance,physical coating or covalent bonding methods are usually used.For example,the use of reagents with multiple functional groups to surface-modify the magnetic nanoparticles so that they can be used for treating different kinds of contaminants.In this study we prepared amino-modified magnetic nanocomposites,and this material was used for the adsorption of heavy metals Cu²⁺in wastewater.The intrinsic performance of the material and its adsorption performance were investigated.The research contents are as follows:Synthesis of materials:Amino groups were grafted onto silica-encapsulated Fe₃O₄ nanoparticles using chitosan solution as a modification reagent.Firstly,Fe₃O₄magnetic cores were prepared by a co-precipitation method.Then silica was coated on the surface of the magnetic core to obtain Fe₃O₄/SiO₂ particles with a core-shell structure using sol-gel method.Finally,a sodium tripolyphosphate?STPP?buffer solution was used as a cross-linking agent to cross-link the chitosan on the of Fe₃O₄/SiO₂ and amino-modified magnetic nano-sorbents?MTPCS?has been synthesized.The adsorbent were characterized by X-ray diffraction?XRD?,transmission electron microscopy?TEM?,specific surface area measurement?BET?,Fourier transform infrared spectroscopy?FT-IR?and X-ray photoelectron spectroscopy?XPS?to study the performance characteristics of the magnetic nano adsorbent.Adsorption experiments:The effects of initial pH,adsorption dose,and initial concentration of heavy metal ions on adsorption were studied by batch experiments.In addition,adsorption isotherms,kinetics and thermodynamics were studied to understand the adsorption mechanism between metal ions and MTPCS.The results show that the adsorption kinetics fits the pseudo-secondary rate mode and the intraparticle diffusion models.The adsorption isotherm conforms to the Langmuir model.And thermodynamic studies confirm that the adsorption process is endothermic and spontaneous in nature.The maximum adsorption occurs at pH=5±0.1.And the adsorbent could be used as a reusable adsorbent with convenient conditions.