Preparation Of Fe₃O₄@pamam Nanomaterials And The Adsorption Property For Cu²⁺

With the rapid development of industry and economy in the world,the problem of heavy metal pollution in water is becoming more and more serious and directly threatening the living environment of human beings.Therefore,it is very important to study the efficient removal technology of heavy metals in water and related basic theories.In this paper,the dendrimer polyamide-amine?abbreviation:PAMAM?was synthesized by the divergence method and the Fe₃O₄ nanoparticles were synthesized by solvothermal method.The Fe₃O₄ nanoparticles were used as the core and grafted PAMAM dendrimers by surface modification.Then a recyclable and high-efficiency Fe₃O₄@PAMAM magnetic nano-adsorption material with core-shell structure was synthesized.The structure,properties of the material and its adsorption behavior for heavy metal Cu²⁺were studied.The specific research contents and research results are as follows:1.Using ethylenediamine and methyl acrylate as raw materials and different generations of PAMAM dendrimers were synthesized by the divergence method.The effects of the synthesis conditions on the yield,purity and structure of the target product were studied.The results are as follows:?1?the optimal molar ratio of ethylenediamine to methyl acrylate is 1:8 when synthesizing 0.5G PAMAM dendrimer;the optimal molar ratio of 0.5G PAMAM dendrimer to ethylenediamine is 1:16 when 1.0G PAMAM dendrimer is synthesized.In the synthesis of half-generation PAMAM dendrimers,an excess of methyl acrylate is required and excess ethylenediamine is required to synthesize whole generation PAMAM dendrimers.?2?The optimum synthesis temperature for PAMAM dendrimers is 25°C.The yield and purity of the PAMAM dendrimer synthesized at 25°C were the highest.The yield and purity of the synthesized 0.5G PAMAM were95.7%and 93.5%,respectively.The yield and purity of the synthesized 1.0G PAMAM were 93.6%and 90.1%,respectively.?3?The end group of the whole generation PAMAM dendrimers are-NH₂ and the end group of the half-generation PAMAM dendrimers are-COOCH₃,which is consistent with the theoretical structure of the PAMAM dendrimers.2.Using Fe?NO₃?₃·9H₂O as raw material,Fe₃O₄ magnetic nano-flowers with particle size of about 40-60 nm were successfully prepared by solvothermal method.Fe₃O₄@KH560-PAMAM nano-composites material with core-shell structure have been successfully synthesized by using Fe₃O₄magnetic nanoparticles as the core,modifying the surface with KH560modifierandthengraftingwith2.0GPAMAMdendrimer.Fe₃O₄@KH560-PAMAM magnetic composite material has the same superparamagnetism as Fe₃O₄ and its saturation magnetization is 44.16emu/g,slightly lower than that of Fe₃O₄?57.12 emu/g?.It can meet the magnetic requirements of materials for magnetic separation of adsorbent materials..3.Theoptimaladsorptionconditions,adsorptionkinetics,thermodynamics and regeneration performance of Fe₃O₄@KH560-PAMAM adsorbent for Cu²⁺were studied.The results are as follows:?1?the optimal adsorption conditions of Fe₃O₄@KH560-PAMAM nano-adsorbent to Cu²⁺are:pH=7,temperature 30°C,adsorption time 30 min.Under the optimum conditions,the saturation adsorption capacity of Fe₃O₄@KH560-PAMAM adsorbent to Cu²⁺is 81.03mg/g.?2?The adsorption kinetics of Fe₃O₄@KH560-PAMAM adsorbent to Cu²⁺was consistent with the second order kinetics adsorption model;adsorption thermodynamics results show that the adsorption process is an endothermic process;the adsorbents have good regeneration performance and the adsorbent rate is 97.2%after repeated use of adsorbent 5 times.