喷雾干燥法制备中孔炭微球及其吸附性能研究

发布时间：2018-06-19 09:04

  本文选题：中孔炭微球 + 喷雾干燥　； 参考：《华东理工大学》2015年硕士论文

【摘要】：中孔炭具有发达的孔结构、优异的导电性、良好的化学稳定性和生物相容性,在吸附分离、催化、电化学等领域具有重要的应用前景。当前合成方法所制备的中孔炭多为粉末状或不具有规则的块体,而在实际应用中,难以展现材料的全部性能。球形材料具有均匀的填充密度和较高的机械强度,以及良好的流动性、低的流体阻力、快速的吸脱附速率等独特的应用优势,然而球形中孔炭的制备,特别是同时控制其微观结构和宏观形貌,并实现其大规模生产,还存在一定的挑战。本工作以间苯二酚、甲醛、二氧化硅溶胶为原料,采用喷雾干燥法制备形貌规整、结构可控的中孔炭微球,该制备方法步骤简单并可实现大规模生产。所制备的中孔炭微球具有发达的孔隙结构,对维生素B12(VB12)具有优越的吸附性能,具备良好的生物吸附领域的应用潜力。进一步将三聚氰胺引入到前驱体,制备出氮掺杂中孔炭微球,丰富了材料的表面化学环境,提升了其吸附性能。论文主要结论如下：(1)以间苯二酚、甲醛、二氧化硅溶胶为原料,采用喷雾干燥法制备中孔炭微球。通过控制干燥温度、前驱体浓度、进料速率以及添加不同量聚乙烯醇(PVA)等条件,优化微球的球形形貌和粒径分布,并得到较佳的实验条件为：前躯体溶液预反应时间1 h,前驱体溶液浓度为7.5 w/v%,干燥温度120℃,进料速率约为750 ml/h,喷雾压力为0.4MPa。通过改变硅溶胶的尺寸、炭前驱体/硅溶胶的质量比(RF/SiO2),实现了中孔炭微球孔隙结构的精确裁剪,使得材料的孔容在1.7-2.7 cm3/g、比表面积在825-1220 m2/g、平均孔径在7-22 nm的范围内调控。(2)研究了中孔炭微球对VB12的液相吸附性能。由于其发达的中孔结构,中孔炭微球对VB12具有极其优异的吸附动力学行为,在吸附前10分钟即可达到总吸附量的90%。在相同孔径的情况下,孔容对吸附量起到决定作用,孔容越大,吸附量在325.8-495.7 mg/g范围内逐渐提高；而在相同孔容的情况下,孔径越大,吸附量越小(3)将三聚氰胺引入到间苯二酚-甲醛体系,采用喷雾干燥技术,制备出氮掺杂中孔炭微球。研究发现,分步混合法制备的氮掺杂微球氮含量为3.3-9.8%,明显高于直接混合法制备氮掺杂微球氮含量的2.7-4.8%。此外,随着三聚氰胺含量的增加,中孔炭微球的孔容随之增加,最高可达3.6 cm3/g。氮掺杂中孔炭微球对水溶液中Cr6+的吸附性能优异,最高吸附量高达361.3 mg/g,热力学计算表明Cr6+吸附是一个自发的吸热过程。氮掺杂炭微球对Cr6+的吸附行为受材料孔容、比表面积和氮含量协同影响。其中,孔容起到最主要的作用,氮掺杂能够部分提高Cr6+吸附量。
[Abstract]:Mesoporous carbon has developed pore structure, excellent electrical conductivity, good chemical stability and biocompatibility, and has important application prospects in adsorption, separation, catalysis, electrochemistry and other fields. Most of the mesoporous carbon prepared by the current synthesis method is powder or irregular block, but in practical application, it is difficult to show the full properties of the material. Spherical materials have the advantages of uniform filling density, high mechanical strength, good fluidity, low fluid resistance, rapid desorption rate and so on. However, the preparation of spherical mesoporous carbon, In particular, there are still some challenges in controlling the microstructure and macroscopic morphology and realizing the large-scale production at the same time. In this work, mesoporous carbon microspheres with regular morphology and controllable structure were prepared by spray drying method using resorcinol, formaldehyde and silica sol as raw materials. The prepared mesoporous carbon microspheres have developed pore structure and excellent adsorption performance for vitamin B12 (VB12), and have good application potential in the field of biosorption. Furthermore, melamine was introduced into the precursor to prepare nitrogen-doped mesoporous carbon microspheres, which enriched the surface chemical environment of the materials and improved their adsorption properties. The main conclusions are as follows: (1) mesoporous carbon microspheres were prepared by spray drying method using resorcinol formaldehyde and silica sol as raw materials. The spherical morphology and particle size distribution of the microspheres were optimized by controlling drying temperature, concentration of precursor, feed rate and adding different amount of polyvinyl alcohol (PVA). The optimum experimental conditions were obtained as follows: the pre-reaction time of the precursor solution was 1 h, the concentration of the precursor solution was 7.5 weeks / v / v, the drying temperature was 120 鈩，

本文编号：2039349