Regulation Of Pore Structure Of Formed Activated Carbon Prepared From Used Powdered Activated Carbon For Its Regeneration

In order to regenerate used powered activated carbon and regulate for pore structure of formed activated carbon, shaped activated carbons have been prepared by mixing used powered activated carbon(UPAC), high temperature coal tar followed by molding, carbonizing and activating. The adsorption capacity of the activated carbons to iodine and methylene blue was measured according to the test method described as China national standards. Also, the specific surface area and pore volume of the activated carbons were determined and analyzed by nitrogen adsorption. The effect of the types and dosage of coal tar, the activation temperature and time were investigated on the adsorption capacity and pore structure of the activated carbons.The results showed that the formed activated carbon could be prepared from UPAC and high temperature coal tar. It has better molding performance and more developed pore structure compared with low temperature coal tar. The resulted carbon originates from three components: high temperature coal tar, UPAC and organic substance adsorbed in UPAC adsorbate in the preparation process. The major formation of the pore structure in the formed activated carbon came from the reaction of steam and UPAC.The dosage of high temperature coal tar has great influence on the adsorption capacity and pore structure of the activated carbons. The less dosage of coal tar used, the better the adsorption performance. The mixture of powdered activated carbon and coal tar according to 1:1.6 exhibited better molding performance and resulted into more developed pore structure. The resulted shaped activated carbon reached to the specific surface area of 1802m2.g-1 and iodine adsorption capacity of 1458 mg.g-1 when the regeneration process was carried out under the condition that the mass ratio of UPAC and coal tar was 1:2.5, the activation temperature was 900? and the activation time was 2h.In order to develop the type of granular activated carbon for caramel decolorization during the regeneration process of UPAC, shaped activated carbons have been prepared by mixing UPAC, coal tar and polyethylene glycol(PEG) followed by molding, carbonizing and activating. The iodine adsorption value, methylene blue adsorption value and caramel decolorization rate of the activated carbon were measured according to the test method described as China national standards. Also, the specific surface area and pore volume of the activated carbons were determined and analyzed by nitrogen adsorption. Thermal decomposition of polyethylene glycol, UPAC, coal tar and their mixtures were demonstrated by thermogravimetric analyzer. The effect of the content and molecular weight of PEG, the activation temperature and time were investigated on the adsorption capacity and pore structure of the activated carbons.The results showed that the formed activated carbon for decolorizing sugar solution could be prepared from UPAC; the addition of the PEG could significantly promote the caramel decolorization rate and methylene blue adsorption value of the shaped activated carbons and the formation of mesoporous. While with a negligible influence of the molecular weight of PEG. The caramel decolorization rate and methylene blue adsorption value of the shaped activated carbon reached to 110% and 205 m L.g-1, respectively, when the regeneration process was carried out under the condition that the mass ratio of coal tar and PEG-4000 was 6:1, meanwhile powdered activated carbon and coal tar was 1:1.6, the activation temperature was 900? and the activation time was 2h.