Preparation And Adsorption Performance Investigation Of Novel Surface Molecularly Imprinted Polymer On The Carbon Material

The deep removal of organic thiophene sulfides in the vehicle fuel oil will be a meaningful attempt to improve the quality of fuel oil from the headstream,which is conducive to solve the environmental pollution caused by sulfide emissions from motor vehicles.Surface molecular imprinting technology is one of the most promising adsorptive desulfurization technologies,which could specificially remove thiophene sulfides from oil products,due to its three prominent features:structure activity predetermination,specificity recognition and wide practicability.Starting with the selection of the support matrix and the optimization of the functional monomer in this paper,two novel surface molecularly imprinted polymers are synthesized using thiophene and dibenzothiophene as template molecule,which are named by hollow surface molecularly imprinted polymer on the porous carbon material?SMIP/HCMS?and surface molecularly imprinted polymer on the?-cyclodextrin porous carbon nanosphere?SMIP/MA@PCNS?,respectively.Adsorption performance evalution and morphology structure characterization are carried out systematically.Surface molecularly imprinted polymer on the porous magnetic carbon material?SMIP/p-Fe₃O₄@C?is prepared using porous magnetic carbon material?p-Fe₃O₄@C?as the support matrix,3-methacryloxypropyl trimethoxysilane?KH570?as the silane coupling agent,methacrylic acid?MAA?as the functional monomer,dibenthiophene?DBT?as the template molecule and ethylene glycol dimethacrylate?EGDMA?as the cross-linker.SMIP/HCMS can be obtained by acid pickling process to remove the magnetic nuclei.The optimum experimental parameters are optimized through comparative experiments,as follows:the annealing temperature is 500°C,the dosage of KH570 and MAA is 2 ml and 1 ml,respectively,and the molar ration of EGDMA and DBT is 1:5.TEM result indicates that SMIP/p-Fe₃O₄@C has a good shell-core structure,and the structure of SMIP/HCMS is obviously hollow.The BET surface area of SMIP/p-Fe₃O₄@C and SMIP/HCMS is 47.05 m²·g^-1 and 224.02 m²·g^-1,respectively.According to the IR result,the peak intensity of some oxygen-containing functional groups,such as carbonyl and hydroxyl groups,has an evident enhancement.The result of static adsorptive experiment shows that the adsorption equilibrium time of SMIP/p-Fe₃O₄@C towards DBT is 120 min,the saturated adsorption capacity is 30.12mg·g^-1,and the imprinting factor is 1.58;SMIP/HCMS achieves the adsorption equilibrium within 80 min,the saturated adsorption capacity toward DBT is 62.06mg·g^-1(10.78 mg S·g^-1),and the imprinting factor is 2.06,which is largely ascribed to the fact that more recognition sites in the imprinted hole are exposed after the acid pickling.Adsorption kinetics,isothermal adsorption and adsorption thermodynamics results show that the adsorption process of SMIP/HCMS is dominated by physical adsorption,and more inclined to multi-layer adsorption,which is a spontaneous and endothermic process.Besides,SMIP/HCMS has an excellent selective adsorption and good regeneration performance.SMIP/MA@PCNS is synthesized using porous carbon nanospheres?PCNS?based on?-cyclodextrin??-CD?as the support matrix,KH570 as the silane coupling agent,thiophene as the template molecule and EGDMA as the cross-linker.Combined with the results of FT-IR and N₂ adsorption-adsorption characterization,the optimum annealing temperature of carbon nanospheres?CNS?is 500°C,and the obtained PCNS-5,owning rich hydroxyl groups on the surface,has a high BET surface area(518.04 m²·g^-1).The optimum dosage of KH570 and EGDMA is 1 ml.Selected from the unsaturated monocarboxylic acid?MAA and AA?,unsaturated dicarboxylic acid?MA and IA?and unsaturated tricarboxylic acid?TAA?,the best functional monomer of polycarboxylic acid is MA?its optimum dosage was 1.39 g?.The results of SEM and TEM indicate that the structure of SMIP/MA@PCNS is a regular carbon nanosphere and the thickness of the surface polymerization layer ranges from 2 to 4 nm.After grafting isomolar unsaturated polycarboxylic acid functional monomers,XPS result shows that the C=O content of MA@PCNS is the highest,indicating that MA@PCNS owns more carboxylic acid functional groups which can adsorb more thiophene molecules.The BET surface area of SMIP/MA@PCNS is increased to 577.83 m²·g^-1,which provides a proof that the pore structure is further enriched by a large number of imprinted cavities on the surface of the polymer layer.The result of static adsorptive experiment indicates that the saturated adsorption sulfur capacity of SMIP/MA@PCNS is 22.6 mg S·g^-1,the adsorption equilibrium time is 120 min,and the imprinting factor is 3.93.Adsorption kinetics,isothermal adsorption and adsorption thermodynamics results show that the adsorption process of SMIP/MA@PCNS is dominated by physical adsorption,and more inclined to single molecule adsorption,which is an endothermic and spontaneous process.In addition,SMIP/MA@PCNS has the preferential selective adsorption ability for thiophene,good structural stability and reproducibility.