From fly ash of forest biomass combustion (FBC) to micro-mesoporous silica adsorbent materials

Abstract According to the EU recommendations on solid residue management, fly ashes derived from biomass combustion and other solid wastes from energy production must be recycled since their disposal in dumps and landfills, etc., leads to environmental and space availability problems. This study is focused on minimization and beneficiation of an industrial waste, fly ash, derived from the combustion of forest biomass in a fluidized bed combustor for subsequent use as a precursor of porous silica materials for environmental applications. The predominant component of fly ashes is silica, which comes from both the original composition of the forest biomass and from the bed of the fluidized combustor. The fly ashes were activated with KOH, at a temperature of 750 °C using soaking time of 60 min. The porosity in these materials is mainly due to the activation of silica and, to a lesser extent, unburned carbons. These materials, that have a surface area, S BET , of up to 654 m 2 /g, are mainly mesoporous (0.186–0.258 cm 3 /g) with a significant proportion of micropores (0.116–0.142 cm 3 /g). Mesoporosity developed mainly in the inorganic part of the fly ash. Fly ash from forest biomass combustion can be used as a precursor of adsorbent materials or as catalyst support.