Preparation Of Superparamagnetic Nanocomposites And Its Adsorption Performances For Cu²⁺

Superparamagnetic nanocomposites are the comibination of organic magnetic nanoparticles andorganic functionalized monomers with different polymerization methods, which aresuperparamagnetic and have special fuctionalization.Superparamagnetic nanocomposites havepotential applied values in the field of water pollution treatment due to its superparamagneticproperty, regeneration and multi-functionalization, etc.In this work, oleic acid modified superparamagnetic nanoparticles (MNPs@OA) were firstlyprepared by improved chemical coprecipitation. Secondly, Br-modified MNPs (MNPs@Br) weresynthesized by ligand exchange reaction and substitution reaction on the surfaces of MNPs@OA.Thirdly, the amine-functionalized superparamagnetic adsorbing nanoparticles (MNPs@NH2) weresynthesized by surface modification of superparamagnetic nanoparticle with surface-initiated atomtransfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) and subsequentlyaminatation with diethylenetriamine (DETA). The nanoparticles were characterized by FI-IR, TEM,XRD, VSM and titration method. The results reveal that the as-synthesized MNPs@NH2issuperparamagnetic and dispersible well in water; the average diameter of the nanoparticles is about10nm and the saturation magnetization is about41.6emu g-1; the available amino groups content onthe particles is3.13mmol g-1.The adsorption performances of the MNPs@NH2for Cu2+were also investigated. The effects ofinitial concentration of Cu2+, pH, ionic strength, amination time, dosage of MNPs@NH2, differentaliphatic polyamines modified MNPs@NH2and temperature on the adsorption performances of theDETA-MNPs as well as adsorption kinetics with different initial concentration of Cu2+ions,adsorption isotherms and regeneration were examined. The results show that the adsorptionefficiency was highly pH-dependent and the optimum pH is5.0; the optimum initial concentration ofCu2+is50mg L-1; the optimum amination time is10h; the optimum dosage of MNPs@NH2is1.35gL-1; the optimum aliphatic polyamine is DETA; the increasing of ionic strength can shorten adorptionequilibrium time and improve adsorption capacity; higher temperature is helpful for adsorption;Theadsorption follows Langmiur kenitics model and reachs equilibrium within20min, the maximumadsorption capacity(qm) was83.33mg g1. Desorption of Cu2+ions from the MNPs@NH2wasconducted in a0.1mol L-1HNO3solution, for96%desorption being obtained every times. After10times adsorption-desorption, the MNPs@NH2still have good adsorption performance.