Preparation And Properties Of Granular Activated Carbon Activated With H₃PO₄

Granular activated carbons(GACS) with high abrasive resistance were prepared by activation with phosphoric acid using the tar as a binder which generated by its own during pyrolysis at low temperature. The technologcial conditions and plasticizing mechanism during the process were studied to provide scientific data and theoretical basis for the preparation of high abrasive resistance granular activated carbon.The GACS were prepared from the wood by H3P04 activation.The method of factor analysis and the orthogonal design were employed to investigate the preparation factors,which effect GAC'S on the pore structural characteristics and the adsorption properties of iodine number and methylene blue were discussed and the optimum process conditions were determined as follow: concentration of phosphoric acid 70%, impregnation ratio of reactive agent to dried material (weight basis) 180% , temperature of kneading 170℃,time of kneading 60min, activation temperature 350℃and activation time 210min.Under optimum conditions, the obtained granular activated carbon has Iodine number 1020.04 mg/g, methylene blue adsorption 225 mg/g, abrasive resistance 88.73%,BET 1486.48m2/g.Moreover, adsorptive capability of GACS was greatly influenced by impregnation ratio and activation temperature,and abrasive resistance of GACS was greatly influenced by temperature of kneading and impregnation ratio.As abrasive resistance of GACS decreases with the increase of impregnation ratio and the decrease in the larger, complex activator method was implemented. The experiment results indicated that abrasive resistance of GACS were improved by the impregnation ratio was reduced.And adsorptive capability of GACS were improved by complex activator.Therefore,GACS with excellent adsorptive capability and high abrasive resistance were prepared by this method.For prepared GACS, specific surface area and pore size distribution analyzer was employed to determine the N2 adsorption—desorption at 77K.The BET equation and BJH methods were used to estimate the surface area and pore size distribution.The scan electric microscope(SEM) and FT-IR were also used to investigate the morphology and chemical functional groups characteristics,respectively.The results show that specific surface area of GACS by complex activator more than the GACS by H3PO4,and which with predominant microporous structures. Surface functional groups and structural were changed by different complex activator,affecting adsorptive capability of the obtained GACS.Obvious effect of phosphoric acid and complex activator on surface shape of the product.