Facile construction of hierarchical porous ultrafine alumina fibers (HPAFs) and its application for dye adsorption

Abstract

Abstract In this paper, hierarchical porous ultrafine alumina fibers (HPAFs) with macropore and mesopore are facial constructed via using the simple PTFE emulsion template and electro-blown spinning process. The effect of different calcination temperatures, 500 °C, 800 °C and 1100 °C on the pore structures of the ultrafine alumina fibers and their dye adsorption performances are systemically investigated. Results show that calcination temperature has a significant effect on the fiber morphology and pore structure, which is of vital importance in adsorption performance of the ultrafine alumina fiber. Thereinto, the HPAF obtained at 800 °C (HPAF-800) exhibits obviously hierarchical porous structure and high specific surface area (226.94 m2 g−1), which attributed to the thermal decomposition of PTFE particles and the surfactants or other dispersants in PTFE emulsion. Further investigation indicates that the HPAF-800 has good dye adsorption performance, especially the high dye adsorption rate towards methylene blue (MB) with the dye removal rate reaches 97.65% within 30 min at 25 °C, which is mainly due to its hierarchical porous structure. The HPAF-800 also shows desired adsorption cycle performance and the ability to regenerate easily. The adsorption kinetics research indicates that the MB adsorption process follows the pseudo-second-order kinetic model very well. The mechanism of the HPAF-800 for dye adsorption is also concerned. Compared with common alumina fibers, the HPAF-800 exhibits special adsorption behavior and enhanced dye removal rate, which originate from its surface macropores and the capillary effect induced by inner mesopores. Finally, the HPAF-800 suggests its potential applications in adsorption as well as related areas, such as catalysis and catalyst supports.