Study On The Preparation And Application Of Surface Functionalized Polystyrene Microspheres And Composite Materials

With the development of nanotechnology,polymer-based nanocomposites（PCM）have received extensive attention due to their diverse structures,rich composition and outstanding performance.Compared with their single components,it is possible for the special structure and controllable morphology of composite materials to apply in the fields of optics,sensors,energy,life sciences,etc.The nano-meter effect caused by the particle size in the nano-meter range further enhanced the significance in the theoretical research.In this paper,the surface of the polymer was functionalized by the copolymerization process,and the polystyrene functional microspheres（PS-CHO）with aldehyde groups on the surface were prepared.The application of microspheres as adsorbents in the treatment of heavy metal ion wastewater was studied.The mechanism of the adsorption process was obtained by comparing the kinetic model of the microspheres before and after adsorption.PS-CHO was further used microspheres as the carrier and the cerium nitrate was chosen as the cerium source,PS-CHO@CeO₂ nano core-shell microspheres were prepared by in-situ precipitation method.The controllable adjustment of the structure and morphology of the composite microspheres could be achieved by changing the concentration of the cerium source and the pH value of the solution,and the optimal reaction conditions could be obtained.The UV photocatalytic activity of the composite microspheres was evaluated by the degradation of methyl orange（MO）.The same type of derivative material-PS-CHO@RGO composite microspheres were synthesized by in-situ reduction of graphene oxide（GO）.The performance of degrading methylene blue（MB）in the presence of 2KHSO5·KHSO4·K2SO4.The specific work of this paper mainly focuses on the following three aspects:（1）The synthesis of PS-CHO microspheres and the study on the adsorption performance of uranyl ions（UO₂2+）First,styrene（St）and acrolein（C₃H₄O）were used as monomers for the polymerization reaction,polyvinylpyrrolidone（PVP）was selected as the sterically hindered ionic dispersant,and azobisisobutyronitrile（AIBN）was used as the initiator.Copolymerization method was used to prepare polystyrene microspheres（PS-CHO）with aldehyde groups on the surface.Uranium acetate/water solution simulates industrial uranium-containing wastewater,using PS-CHO microspheres as an adsorbent to finish the effective adsorption of low-concentration heavy metal wastewater.The experimental results show that under the action of electrostatic attraction,UO₂2+in the uranyl acetate/water solution can be captured by the aldehyde groups on the surface of the microspheres to form an intermediate hydrated compound.The oxygen in the system is the oxidant,and the uranyl ion is finally formed nano-oxide particles and concentrated on the surface of the microspheres.The results of adsorption kinetics proved that the best adsorption effect can be obtained in a system with a reaction temperature of 313 K,an adsorbent dose of 0.4 g·L-1,an initial uranyl ion concentration of 20 mg·L-1 and a pH value of 6.0,the rate can reach 92.13%,and the data fitted by the quasi-second-order kinetic mode,which can better describe the adsorption process.In the elution experiment,perchloric acid is the best eluent,and PS-CHO microspheres exhibit good acid and alkali resistance and can be reused.（2）Study on the controllable preparation of PS-CHO@CeO₂ nano core-shell microspheres and its photocatalytic degradation performanceThis chapter cited the thermodynamic effect of the colloidal system to develop a simple and convenient method,nano-cerium oxide particles were successfully deposited on the surface of polystyrene aldehyde-based microspheres.During the reaction process,the exposed aldehyde groups on the surface of the microspheres provided the binding sites.According to the principle of electrostatic attraction,trivalent cerium ions（Ce3+）spontaneously deposit on the surface of the microspheres and combine with the aldehyde groups.With the oxidation of oxygen,PS-CHO@CeO₂ nanocomposite microspheres were prepared.CeO₂ nanoparticles with the particle diameter of 3-4 nm were uniformly distributed on the surface of the microspheres,and the composite microspheres presented a clear raspberry-like core-shell structure.Compared with the reported process for preparing polymer microspheres loaded with nano-cerium oxide,the method reported in this chapter does not involve additional dispersants and oxidants,and the microspheres used as carriers do not need to be pre-treated.The results of a series of simultaneous experiments show that simply changing the concentration of the cerium source and the pH value of the reaction system can realize the controllable adjustment of the composite microspherical morphology and the loading rate of cerium oxide.The catalytic activity of PS-CHO@CeO₂ composite microspheres was verified by photodegradation of methyl orange dye.Under ultraviolet light,the degradation rate of methyl orange can reach 93.03%within 120 min.What’s more noteworthy is that the composite microspheres also exhibit good structural stability,and still maintain high catalytic activity after four cycles of use（3）Study on the controllable preparation of PS-CHO@RGO composite microspheres and its catalytic degradation performanceIn this chapter,the in-situ polymerization method was used,based on the self-assembly of the ionized π electrons of the graphene surface groups and the π-π conjugated polymer surface.According to the principle,graphene oxide（GO）was reduced by sodium borohydride and coated on PS-CHO microspheres to prepare PS-CHO@RGO composite microspheres.The microspheres interspersed between the RGO sheets could effectively improve the stacking problem of graphene-based materials.The electrical conductivity of PS-CHO@RGO composite microspheres increases with the increase of the GO content.When the RGO volume fraction reaches 0.98 vol.%,the electrical conductivity has a five-order gradient increase,which proves the emergence of the permeation threshold.The microspheres are bleed.Methylene blue（MB）was chosen as the target pollutant,the catalytic activity of PS-CHO@RGO composite microspheres in the presence of a small amount of potassium peroxymonosulfate（PMPS）was explored and the degradation mechanism was proposed.PS-CHO@RGO composite microspheres can stimulate PMPS to generate strong oxidizing sulfate radicals（SO4·-）,and the oxidative degradation rate of methylene blue（MB）is significantly increased,reaching more than 98%in 60 minutes.PS-CHO@RGO composite microspheres are recycled through high-speed centrifugation.