Highly efficient synthesis of hexagonal boron nitride short fibers with adsorption selectivity

Abstract

Abstract Hexagonal boron nitride (h-BN) is widely used in the fields of pollutant adsorption and aerospace due to its low density, good electrical insulation, and excellent thermal conductivity. The precursor was prepared by using a liquid-phase method and then calcined in a flowing nitrogen atmosphere to achieve highly efficient preparation of high-purity h-BN and obtain h-BN short fibers. The chemical composition and generation rate of the precursor prepared at different BA(H3BO3):M(C3N6H6) ratios were characterized. The possible chemical synthesis reactions for converting raw materials into h-BN were discussed. The morphology and composition of h-BN short fibers were investigated, and the selective adsorption and reusability of h-BN short fibers was also analyzed. Results indicated that when the ratio of BA:M was 3:1, the generation rate of the precursor was the largest, reaching 85.424%. The maximum conversion rate of h-BN prepared from the precursor calcined in a flowing nitrogen atmosphere was 19.51%. When the BA:M ratio was 1:1 or 3:1, the obtained h-BN short fibers contained the least impurities, and the atomic content of O element was only 5.85%. The maximum specific surface area of h-BN fibers was 1144\u202fm2/g and the main pore sizes were 1.72\u202fnm and 3.78\u202fnm. The maximum adsorption rate and adsorption capacity of h-BN short fibers to methylene blue (MB) reached 95.413% and 494.5\u202fmg/g, respectively. The h-BN short fibers can rapidly adsorb MB from a mixed solution of MB and Cu2+, indicating that they have high adsorption selectivity for MB. After 5 times adsorption, the adsorption rate of the h-BN fibers to MB was still larger than 90%. This finding showed that the high-purity h-BN short fibers prepared in a flowing nitrogen atmosphere had the potential to selectively adsorb contaminants in the field of water treatment.