The Preparation Of Composite Modified Activated Carbon Fibers And Its Performance Of Adsorbing SO₂

In this paper, the polyvinyl pyrrolidone (PVP)/tetrabutyl titanate (TBT) composite fibers and polyvinyl pyrrolidone/cobalt acetate composite fibers were prepared by electrostatic spinning. After preoxidation, carbonization and activation, the TiO2-activated carbon fibers (TiO2-ACF) and Co3O4-activated carbon fibers (Co3O4-ACF) were prepared. These two types of ACF were characterized and analyzed. We made experiment of adsorbing SO2 by the two kinds of ACF, and study the effect of different adsorption conditions on the adsorption rate of adsorbing low concentration SO2 by the two kinds of ACF.Through analyzing scanning electron microscope (SEM), the optimum spinning conditions of two composite fibers were obtained. The optimum spinning conditions of PVP/TBT composite fibers were as flows:spinning voltage was 12 kV, precursor solution was mixed by 10 mL PVP alcohol solution and 2 mL tetrabutyl titanate solution, spinning distance was 15 cm, angle was 15°. The optimum spinning conditions of PVP/cobalt acetate were as follows:spinning voltage was 12 kV, precursor solution was mixed by 10 mL PVP alcohol solution and 1.5 g cobalt acetate, spinning distance was 15 cm, angle was 15°. Through thermo gravimetry analysis we conclude the preoxidation temperature and the carbonization temperature rage of the two kinds composite fibers. We select temperature of preoxidation and carbonation as follows,:preoxidation temperature was 250℃, carbonation temperature were 500℃,600℃,700℃,800℃; PVP/cobalt acetate composite fibers: preoxidation temperature was 260℃, carbonation temperature were 400℃,500℃,600℃, 700℃. Through x-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) analysis, we found that the anatase TiO2 was appearance in the PVP/TBT composite fibers at 500℃. When the temperature was over 600℃, there were not only anatase TiO2 but also rutile TiO2. We choose 500℃as the carbonation temperature of PVP/TBT composite fibers. We also found Co3O4 was appearance in the PVP/cobalt acetate composite fibers at all the carbonation temperature. But when the temperature was over 500℃, the mechanical strength of the fibers was not good and fragile. So we choose 400℃as the carbonation temperature of the PVP/cobalt acetate composite fibers. The two kinds of carbon fibers were impregnated in the 1 mol/L HNO3 solution for 12 h, then dry and activated at 600℃. The obtained activated carbon fibers were characterized by BET analysis. The results were that the specific surface area of TiO2-ACF and Co3O4-ACF were 1146.7 m2/g and 1238.5 m2/g. The micropore volume proportion was 98% in both of the two kinds ACF.Through experiment of adsorbing low concentration SO2 we conclude that the adsorption rate of SO2 by Co3O4-ACF was higher than TiO2-ACF; The adsorption rate of SO2 was increasing with the increase of SO2 concentration in both of the two kinds ACF; The adsorption rate of SO2 was the highest at 20℃in both of the two kinds ACF; The adsorption rate of SO2 was increasing with the increase of the adsorption time, but the increase of the adsorption rate was slow because of that the concentration of SO2 is low and the driving force is not enough.