Study On The Preparation Of Processing And Properties Of Granular Activated Carbon Separated From Fly Ash

In this thesis,in order to resolve the problem of the fly ash of Tianjin PipeReduction Plant, the carbon separated from the fly ash was reasonably developed togranular activated carbons, which were of great practical values. In this way theindustrial waste was recycled and the environment was also protected.The optimal preparation process of GACs was decided by an orthogonal design.Under the optimal preparation process GACs could be obtained by physical activationwith a pretreatment in ammonium-salt solution. GACs could also be prepared byphysical activation with KOH pretreatmen. The activation process of GACs from thefly ash was investigated. The influences of the activation process on the pore structureand adsorption capacity of GACs were systematically studied.The results show that GACs with the SBET of 582.7m2/g and yield rate of 21.46%can be obtained from the fly ash in physical activation. The specific surface area andthe yield rate of GACs were enhanced to 743.6m2/g and 40.8% by a pretreatment inammonium-salt solution (the volume ratio of ammonium-salt solution to carbonpowder (ml:g) is 4:1). GACs with the SBET of 820.9m2/g and yield rate of 30.35% canbe obtained from the fly ash by the pretreatment with KOH. The pretreatment withKOH can affect the carbonization and KOH can also react with SiO2, Al2O3, etc, thatwould decrease the ash content of GACs in the HCl washing and improve theadsorption capability of GACs.The results of X-ray diffraction (XRD) reveale that GACs made by variousactivation methods have different micro-crystal structures. The micro-crystal size andthe layer distance of GACs were calculated according to the equation of Bragg andthe formula of Sherry. The results show that the degree of graphitization decrease andthe content of the amorphous carbon increase with enhancing the specific surface areaof GACs. The irregular degree of micro-crystal structure increase.