Development of a non-conventional sorbent from fly ash and its potential use in acid wastewater neutralization and heavy metal removal

This work focuses on the development, characterization and use of a non-conventional sorbent (NCS) using a blend of petroleum coke fluidized bed combustion fly ash and the organic waste fraction from a Kraft cellulose wastewater facility. In addition to an increase in specific surface area and particle size distribution, NCS showed a similar chemical composition as petroleum coke fly ashes. Leaching tests revealed the non-hazardous character of all NCSs obtained according to the European standards for landfill disposal of waste materials, being Na, S, Ca, V, Ni, Zn and As detected as mobile major and trace elements. With these results, the sample NCS3 was selected for a further application in experiments of neutralization and heavy metal removal from acid wastewater. Neutralization and heavy metal fixed-bed removal tests showed that NCS3 is a suitable sorbent material (maximum removal capacities of 8.1 and 28.3 mg/g for Cu2+ and Pb2+, respectively) that can be used at pH 4, showing greater buffering and Cu2+ and Pb2+ removal capacities.