Preparation And Properties Of Safranin T Molecular Imprinted Polymer

Chinese industry is developing rapidly,and economic growth is also advancing by leaps and bounds.At the same time,a large amount of polluted waste water is discharged with industrial development,which will become an obstacle to strengthening of the green Silk Road.The treatment of waste water pollution has become one of the important problems to be urgent in our country.Among them,the printing and dyeing waste water containing a lot of organic pollutants is mainly composed of dye intermediates in the printing and dyeing industry,and Saffron T(ST)is one of the main components.Investigation and research showed that it was difficult to degrade it well with traditional treatment methods.However,a new adsorbent material,molecular imprinted polymers(MIPs),has a good selective adsorbency to saffron T in water,which can effectively degrade saffron T and reduce its pollution to the environment.This new adsorbent material not only has a large adsorption capacity,but also has a strong ability to select and identify the target substance,and can be reused after elution.Therefore,the research on the new molecular imprinted polymer adsorbent has become a hot spot in the polluted wastewater treatment industry.In this paper,two methods of bulk polymerization and Pickering emulsion polymerization were used to synthesize Saffron T molecular imprinted polymers,and they were characterized by scanning electron microscopy(SEM),UV-Vis absorption spectroscopy and Fourier transform infrared spectroscopy(FT-IR).The adsorption process and mechanism of the material were analyzed by isothermal adsorption and adsorption kinetics.The major conclusions are as follows:The intermolecular interaction between template molecule ST and different functional monomers(?-methacrylic acid(MAA),acrylamide(AM))in acetonitrile solvent was studied by ultraviolet spectrum analysis.And the intermolecular interaction between template molecule ST and functional monomers in acetonitrile solvent with different concentrations and ratios were also explored.The influence of the amount of solvent acetonitrile on the adsorption property of MIPs polymer was further investigated.The results showed that the UV-Vis spectra of template molecule ST and functional monomer MAA in acetonitrile changed significantly more than that of template molecule ST and functional monomer AM in acetonitrile.The greater the change of the UV-Vis absorption spectrum,the stronger the intermolecular force,so the intermolecular force between the template molecule ST and the functional monomer MAA in acetonitrile solvent was significantly higher than the intermolecular force between the template molecule ST and the functional monomer AM in acetonitrile solvent;In acetonitrile solvent,when the concentration ratio of the template molecule ST to the functional monomer MAA was 1:4,the UV-Vis absorption spectrum of the template molecule ST and the functional monomer MAA changed most significantly,indicating that the molecular interaction force between template molecule ST and functional monomer MAA in acetonitrile solvent was the highest,so the concentration ratio was the best;According to the differential UV-Vis absorption spectrum analysis of the assembled system,during the polymerization process,it was speculated that the formed MIPs polymer and Saffron T had 9 specific binding sites,and may mainly formed the Saffron T-3MAA type complex.The amount of solvent acetonitrile had a great influence on the adsorption performance and structure of MIPs.By comparing the performance of polymers prepared with different amounts of acetonitrile,it could be concluded that when the amount of acetonitrile was 25 mL,the adsorption performance of the prepared MIPs was the best.The surface morphology and structure of the prepared Saffron T molecular imprinted polymer were analyzed by scanning electron microscope(SEM)and infrared(FT-IR).The adsorption properties of MIPs and NIPs(non-molecular imprinted polymers)in different concentrations of ST acetonitrile solution and the selective adsorption of the polymers to the template were further investigated by using kinetic adsorption curves and isothermal adsorption curves.The results showed that the Saffron T molecular imprinted polymer prepared by the bulk polymerization method with ST as template had a abundant of binding sites on the surface,and had excellent ability to select and recognize template molecules;During the polymerization process,the template molecules were only arranged in the polymer structure through intermolecular forces,and did not participate in the polymerization reaction;According to the kinetic adsorption curve,when the concentration of ST acetonitrile solution was 5.6?g/mL,MIPs reached adsorption equilibrium at 80 min,the adsorption capacity was about 61780?g/g,while NIPs reached adsorption equilibrium at 60 min,the adsorption energy was about 25880?g/g.According to the isotherm adsorption curve,when the concentration of ST acetonitrile solution reaches 8.0?g/mL,MIPs and NIPs both reached the adsorption saturation state.At this time,the adsorption capacity of MIPs and NIPs were 67210?g/g and 28170?g/g,respectively.Under the adsorption equilibrium state,the imprinting factor of molecular imprinted polymer was about 2.386,indicating that ST was successfully imprinted in the polymer as an imprinted molecule,and the polymer had selective recognition for the template.The molecular imprinted polymer of saffron T prepared by Pickering emulsion polymerization and its adsorption properties were studied by SEM and FT-IR;The nano-SiO₂particles were modified by reducing the surface-OH content of nano-SiO₂,and the modified nano-SiO₂ could effectively enhance the stability of the emulsion.The effect of the amount of nano-SiO₂ on the preparation of saffron T by Pickering emulsion polymerization was further studied.The adsorption properties of MIPs and NIPs in different concentrations of ST acetonitrile solution and the influence of polymer on the selective adsorption of template were studied by kinetic adsorption curve and isothermal adsorption curve.The results showed that the reaction of the Pickering emulsion polymerization method was more thoroughgoing,the addition of stabilizers made the prepared emulsion more stable,the prepared polymer had a more uniform particle size and better dispersibility,and there were abundant binding sites on the polymer surface,which ensured that the polymer had a very high ability of selection and recognition in application;According to the kinetic adsorption curve,when the concentration of ST acetonitrile solution wae 5.6?g/mL,the adsorption equilibrium of ST-MIPs reached106730?g/g at 80 min,while that of NIPs reached the adsorption equilibrium at 60 min with the adsorption capacity of 34210?g/g.According to the isothermal adsorption curve,when the concentration of ST reached 8.0?g/mL,both MIPs and NIPs reached the adsorption saturation state.At this time,the adsorption capacity of MIPs was 109720?g/g,while that of NIPs was only 35170?g/g.Through comparison,it was found that the adsorption capacity of the polymer prepared by Pickering emulsion polymerization method was significantly higher than that of the polymer prepared by bulk polymerization method,which indicated that during the polymerization process of Pickering emulsion polymerization method,the template molecule left more identification holes on the polymer.This illustrated that the Saffron T molecular imprinted polymer prepared by Pickering emulsion polymerization method had higher affinity,better selective recognition of Saffron T,and stronger adsorption capacity.