Production of granular activated carbons from select agricultural by-products and evaluation of their physical, chemical and adsorption properties

Representative samples of soft, low density, group 1 (rice straw, rice hull s, sugarcane bagasse) and hard, high density, group 2 agricultural by-produ cts (pecan shells) were converted into granular activated carbons (GACs). G ACs were produced from group 1 and 2 materials by physical activation or fr om group 2 materials by chemical activation. Carbons were evaluated for the ir physical (hardness, bulk density), chemical (ash, conductivity, pH), sur face (total surface area), and adsorption properties (molasses color remova l, sugar decolorization) and compared with two commercial reference carbons . The results show that the type of by-product, binder, and activation meth od determine the properties of GACs. Regardless of the binder, sugarcane ba gasse showed a better potential than rice straw or rice hulls as precursor of GACs with the desirable properties of a sugar decolorizing carbon. Pecan shells produced GACs that were closest to the reference carbons in terms o f all the properties investigated. (C) 1999 Elsevier Science Ltd. All right s reserved.