Synthesis and Characterization of Porous Ceramic Hollow Fibers with Nano-Molecular Size

الملخص

This research exhibits a method for the fabrication of nano molecular size ceramic
porous hollow fibers, using the internal diffusion technique. This method is based on
preparation a spinning solution consists from nano gamma alumina < 50nm in an aqueous
mixture of sodium alginate, and calcium carbonate. The mixture is spun into a lactic acid
coagulation bath of pH= 1.6 to achieve ionic cross-linking. The green transparent ceramic
hollow fibers were dried under ventilation at ambient temperature for 48h and sintered at
different temperatures 1100 oC-1350 oC for 2h. The synthesized fibers were characterized
and the effect of sintering temperature on surface morphology was studied. The phase
transformation from gamma to alpha was specified by x-ray diffraction, at 1100 oC a few
small and sharp peaks of α-alumina started while at 1250 oC α-alumina with a highly
crystalline structure was obtained. Microstructure and surface morphology of nano ceramic
fibers were studied at different sintering temperatures, a homogeneous particle distribution
was gained at a temperature of 1250 oC. The thermal gravimetric analysis was referred to
an existence of two thermal steps occurred during thermal treatment, dehydration up to 250
oC and alginate dehydration and decomposition from 250 oC to 400 oC. The nitrogen
isotherm behavior indicates to a mesoporous / macroporous substance, an appearance of
type H-2 hysteresis loop. BJH adsorption and desorption average pore diameter (4V/A)
14.4408 nm and 17.7124 nm respectively. Single point surface area is 9.268 m²/g, single
point adsorption total pore volume is 0.023 cm³/g. The average interior and exterior pore
size by mercury intrusion were 20 nm and 50 nm respectively.