Technological Study Of Preparing ACF By Using Old And Useless Cellosilk

Activated carbon fiber (ACF) was prepared by using worn-out organic cellosilk as precusor, carbonized in nitrogen, and activated with carbon dioxide and potassium hydroxide in this paper. Selection of raw material, together with carbonization and activation conditions on structure and properties of the ACF were studied. The ACF was characterized by means of Fourier transformation infrared (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), element analyses and auto-adsorption measurement and so on.(1) It was found that adsorption capacities to methylene blue increased with increasing activation temperature, then decreased. By adsorption capacity, the best activation temperature was 900℃for cotton-cloth, 950℃for organic-silk and 850℃for caddice. The activation yield ratio obviously decreased with activating temperature increasing: the yield change of caddice ACF was the fastest; second was organic-silk ACF; the yield ratio of cotton-cloth ACF was relatively lower at a low temperature, but it was little change with activation temperature. The activation shrinkage ratio increased with activation temperature extending change, the shrinkage ratio of cotton-cloth and organic-silk ACF was little change with activation temperature, but caddice ACF was great change. Three kinds of materials were activated by CO2 and H2O as activating agent: under the same activating agent conditions, adsorption capacities of ACF to iodine and methylene-blue increased with activation temperature increasing, then decreased; different activation agent conditions, preparing ACF by using CO2 as activating agent was better than H2O.(2) According to old and useless cotton-cloth, Effects of carbonization condition on the structure and property of cotton-cloth ACF were studied, and the best carbonization conditions were obtained. Influence of carbonization temperature was very obviously for the yield ratio. The yield ratio obviously decreased with carbonization temperature increasing, but the shrinkage ratio increased. Adsorption capacity of cotton-cloth ACF to iodine and methylene blue increased with carbonization temperature and time extending, then decreased. The adsorption capacity reached maximum when carbonization temperature was 750℃and carbonization time was 50min. It was shown that the carbonization temperature was 750℃and the carbonization time was 50min.(3) The properties of preparing cotton-cloth ACF by CO2 as activating agent were studied, and the best activation conditions were chosen. Activation temperature and time were little effect for shrinkage ratio of cotton-cloth ACF. Specific surface area and adsorption capacity reached maximum when activation temperature was 900℃and activation time was 80min.The effect of activation time on the structure and property was also important. Adsorption capacity of cotton-cloth ACF to iodine and methylene-blue increased with flow ratio of activating agent extending, then decreased. It was found that the activation temperature was 900℃, the activation time was 80min, and the flow ratio of activating agent was 200ml/min.(4) The properties of preparing cotton-cloth ACF by KOH as activating agent were studied, and the best activation conditions were obtained. Adsorption capacity of cotton-cloth ACF increased with the KOH solution concentration increasing, then decreased, but yield yatio was descending trend. Variation law of specific surface area and adsorption capacity is identical. The effects of activation temperature on the activation yield ratio and specific surface area were obvious. The specific surface area of cotton-cloth ACF by KOH as activating agent increased with activation temperature extending, and reached maximum when the activation temperature was 850℃, then decreased; the specific surface area increased with activation time extending, then decreased, but the yield ratio shown descending trend. The results shown that the dipping time was 6h, the KOH solution concentration was 20% (wt%), the activation temperature was 850℃,and the activation time was 60min.(5) Compared activation process by using KOH and CO2 as activating agent, it was shown that the specific surface area and adsorption capacity of cotton-cloth ACF with KOH was better than the one with CO2.