Coal fly ash-slag-based geopolymers: microstructure and metal leaching.
This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilize a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.
Izquierdo
Maria
M
Institute of Earth Sciences Jaume Almera-CSIC, Lluis Solé Sabaris s/n 08028 Barcelona, Spain. mariaizq@ija.csic.es
Querol
Xavier
X
Davidovits
Joseph
J
Antenucci
Diano
D
Nugteren
Henk
H
Fernández-Pereira
Constantino
C
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D003031:Coal; D060729:Coal Ash; D004785:Environmental Pollutants / Q000302:isolation & purification*; D006256:Hazardous Waste / Q000517:prevention & control; D019216:Metals, Heavy / Q000302:isolation & purification*; D052638:Particulate Matter / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D003031:Coal; D060729:Coal Ash; D004785:Environmental Pollutants; D006256:Hazardous Waste; D019216:Metals, Heavy; D052638:Particulate Matter; D011108:Polymers; D002244:Carbon