| For the purpose of relieving the environmental pollution, which is evoked by sulfur-bearing oil combustion, this research is an attempt to improve the quality of vehicle fuels from the headstream by an advanced desulfurization method. The surface molecularly imprinted polymer(SMIP) is a novel adsorbent for efficient desulfurization. However, the poor mass transfer rate, massive imprinted polymer layer and limited specific surface areas of the existing SMIP are needed to be improved. Thus, this research is to start off with the employment of support materials. Microporous carbon nanospheres(PCNS) and ordered mesoporous carbon nanospheres(OMCNS) obtained through hydrothermal method are chosen as supports of SMIP, as well as the acidified nonporous carbon nanospheres(a-NCNS) and acidified active carbon(a-AC) as comparative supports. Based on these supports, four sorts of SMIP are prepared through identical processes. The morphology and structure of each support and SMIP are characterized and analyzed. And the adsorption performances of each SMIP are tested and compared with each other. Besides, the current achievements on the preparation of desulfurization oriented SMIP by other researchers are also taken into consideration to investigate how the supports influence the adsorption performance of SMIP. This work may provide some referential experiences on support screening, template imprinting and adsorption mechanism, which would be beneficial to achieve the goals of organic sulfide separating and recycling. The main results are as follows:(1) Preparation and structural feature of the supports. PCNS and OMCNS can be controllably obtained by tuning the hydrothermal conditions. The PCNS with average diameter of 360 nm and abundant microporous structures(surface area: 607.5 m2 g-1, pore size: 1.25 nm) can be got by hydrothermally treating glucose solution as carbon source(0.4 mol L-1) at 180℃ for 24 h. The OMCNS with average diameter of 130 nm and abundant mesoporous structures(surface area: 488.02 m2 g-1, pore size: 3.00 nm) can be got by hydrothermally treating phenolic resin(phenol: 0.6 g, formalin: 2.1 m L) as carbon source and triblock copolymer PF127(0.96 g) as soft template at 130℃ for 24 h. The a-NCNS sized 360 nm with surface area of 9.0 cm2 g-1 and a-AC(surface area: 1141.5 m2 g-1, pore size: 2.10 nm) are used as comparative supports. PCNS, OMCNS and a-NCNS have nice dispersibility and good uniformity while a-AC is irregularly shaped blocks.(2) Preparation and structural feature of SMIP. Four sorts of SMIP are prepared through liquid polymerization method based on these supports with dibenthiophene(DBT) as template. The average size of SMIP/PCNS(surface area: 725.3 m2 g-1, pore size: 2.56 nm) and SMIP/a-NCNS(surface area: 19.6 m2 g-1, pore size: 2.77 nm) are both around 390 nm with 15 nm-thick polymer layer. And the average size of SMIP/OMCNS(surface area: 327.61 m2 g-1, pore size: 2.00 nm) is about 140 nm with 5 nm-thick polymer layer. While the SMIP/a-AC(surface area: 2045.0 m2 g-1, pore size: 3.17 nm) has an inhomogenous polymer layer.(3) Adsorption performances of SMIP. The static adsorption experiments are designed to measure the adsorption behaviors occurred on the surface of SMIP. The tests are carried out in the simulated oil solution of DBT(0.8 mmol L-1) at 298 K. The adsorption equilibrium times(te) of SMIP/PCNS, SMIP/OMCNS, SMIP/a-NCNS and SMIP/a-AC are 2.5, 1.5, 2.5 and 1.5 h, respectively. The saturated adsorption amount(Qe) of each SMIP is 118.1, 197.6, 95.7 and 120.2 mg g-1, respectively. And the imprinting factor(fimp) of each SMIP is 1.81, 2.30, 2.37 and 1.16, respectively. These four sorts of SMIP all have excellent structural stability and reproducibility. All adsorption processes fit better with pseudo-first-order model. And the adsorption processes are all multilayer adsorption with various interactions occuring simultaneously. In addition, all the adsorptions are endothermic and spontaneous. Among these four sorts of SMIP, porous and spherical structured SMIP/PCNS and SMIP/OMCNS performed better. Only 5 mg of SMIP/OMCNS can pull the concentration of DBT solution(10 m L) down from 99.6 ppm(0.8 mmol L-1) to 32.4 ppm(0.26 mmol L-1).(4) The influence of structural features of support materials on the adsorption behaviors of their corresponding SMIP. A systematic investigation has been done to compare the four sorts of SMIP prepared in this paper with related works in literatures. It can be found that the properties of support affect the te, Qe and fimp values of SMIP. The preferable support should have regular shape, large active surface area, plenty pores and nice dispersibility besides its structural stability. These features can ensure the corresponding SMIP large surface area, uniform polymer layer, high grafting rate and good dispersibility, which are beneficial to improve the mass transfer and accessibility of DBT to SMIP. On the other hand, the support does not affect the nature of SMIP adsorption towards DBT, which is an endothermic, spontaneous and selective physical adsorption process. Besides, SMIP generally has excellent structural stability and reproducibility. |
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