Preparation Of Polyethyleneimine Functionalized Magnetic Nano Materials And Their Adsorption Properties For Fucoidan

Fucoidan has attracted scientific interest in the past few decades due to its extensive biological activities and potential clinical applications.Fucoidan are usually obtained from brown algae through multi-step extraction and purification process,and there is no standardized method for extracting and purifying fucoidan.The traditional purification methods of fucoidan are often time-consuming,high energy consumption,low efficiency and secondary pollution,which hinder the industrial applications.Therefore,it is of great significance to develop an efficient and environmentally friendly method to recover fucoidan from aqueous solution.In recent years,colloidal dispersed magnetite(Fe₃O₄)nanoparticles(MNPs)have attracted extensive attention as a promising magnetic adsorbent due to their excellent magnetic properties and surface modification.In this paper,PEI-functionalized magnetic Fe₃O₄nanoparticles and PEI-functionalized magnetic Fe₃O₄nanoparticles loaded with carbon nanotubes were designed for purification and adsorption of fucoidan.Magnetic nanoparticles modified with PEI functional groups have abundant active sites,which can be electrostatic attracted to the sulfate group of fucoidan,and then achieve the rapid and selective separation of compounds from complex fluid solutions through the external magnetic field.Compared with the traditional treatment methods,using PEI-functionalized magnetic nanoparticles has many advantages of fast,simple,energy saving and economy,which provides new ideas in the field of purified fucoidan.The main contents of this paper are as follows:Magnetic Fe₃O₄nanoparticles were prepared by polyol method.PPS surface pretreatment was carried out on the magnetic Fe₃O₄nanoparticles to make them chemically anchored on the surface of MNPs and make MNPs have strong negative charge.PEI-MNPs with stable performance,good monodispersity and abundant amino groups on the surface were prepared by adjusting the p H of PEI reasonably to achieve the electrostatic attraction bonding with MNPs-PPS.In order to achieve the best state of PEI-MNPs nanoparticles,the optimal PEI binding p H is 6-7,the optimal modification weight ratio is PEI:MNPs-PPS=1:20,the optimal modification time is 5min,and the optimal modification temperature is 25?.XRD,FTIR,TGA and TEM were used to confirm the successful coating of PEI on the magnetic Fe₃O₄nanoparticles,which formed a shell with a thickness of about 5 nm was formed on the magnetic Fe₃O₄nanoparticles,and the surface modification of PEI did not affect the internal structure of the magnetic nanoparticles.By comparing the adsorption effects of PEI-MNPs and MNPs-PPS on fucoidan under different initial p H,it was found that magnetic Fe₃O₄nanoparticles modified by PEI covered with positively charged amino groups could better bind to fucoidan,and the adsorption effect of fucoidan can be achieved in a wide p H range.The adsorption experiments of PEI-MNPs with Fuc,Lys and phytic sodium were further studied to prove that the binding of PEI-MNPs with fucoidan was carried out through electrostatic binding.The adsorption kinetics results showed that the adsorption of PEI-MNPs on fucoidan was more likely to be chemical adsorption.Isothermal adsorption curves indicate that the adsorption process of PEI-MNPs on fucoidan was more likely to be monolayers.Thermodynamic data analysis showed that the adsorption process of PEI-MNPs on fucoidan was exothermic reaction.After four cycles of PEI-MNPs on fucoidan,the adsorption effect of fucoidan still maintained a good level.Using carbon nanotubes and iron acetylacetone as raw materials,CNTs@Fe₃O₄was synthesized by polyol method,which solves the difficult problem of carbon nanotubes recovery.The surface functionalization of CNTs@Fe₃O₄was carried out by using PEI,and the polyethyleneimine-coated carbon nanotubes supported Fe₃O₄composite(PEI-CNTs@Fe₃O₄)were prepared and used to study the adsorption of fucoidan.XRD,FTIR,TEM and TGA data analysis of PEI-CNTs@Fe₃O₄confirmed the surface deposition of Fe₃O₄in CNTs and the successful modification of PEI.According to the adsorption behavior of PEI-CNTs@Fe₃O₄on fucoidan,it can be found that PEI-CNTs@Fe₃O₄adsorbent could quickly adsorb fucoidan and reached the adsorption equilibrium for 30 min.The adsorption mechanism shows that the adsorption of fucoidan on the surface of PEI-CNTs@Fe₃O₄adsorbent is more in line with the pseudo-second-order reaction kinetics and Langmuir isothermal adsorption model,and the results were more inclined to single layer chemical adsorption,and the thermodynamic data showed that the adsorption reaction was endothermic.At 298 K,308 K and 318 K,the maximum adsorption capacity can reach 405.6,415.7 and 433mg·g^-1,respectively.After three cycles of reuse,the adsorption effect of PEI-CNTs@Fe₃O₄on fucoidan was still more than 80%.The new composite material is expected to be more widely used in the field of adsorption due to its green and efficient adsorption performance.