Chemical stability of geopolymers containing municipal solid waste incinerator fly ash.
Municipal solid waste incinerators every year produce tons of fly ashes which, differently from coal fly ashes, contain large amounts of toxic substances (heavy metals, dioxins, furans). The stabilization/solidification (S/S) technology known as geopolymerization is proposed with the purpose to bond physically and chemically incinerator fly ashes (IFA) in a solid matrix, in order to reduce pollutant mobility. The chemical stability of geopolymers with Si/Al ratio of 1.8-1.9 and Na/Al ratio of 1.0, synthesized by alkali activation of metakaolin and the addition of 20wt% of two different kinds of IFA, is presented. The concentration of the alkaline solution, water to solid ratio and curing process have been optimized. The room temperature consolidation of IFA containing geopolymers has been tested for leachability in water for 1day, accordingly to EN 12457 regulation and extended to 7days to increase the water attack on solid granules. Leachable metals in the test solution, determined by ICP_AES, fall within limit values set by regulation for non-dangerous waste landfill disposal. Geopolymeric matrix evolution with leaching time has been also evaluated in terms of pH and electrical conductivity increase in solution.
Lancellotti
Isabella
I
Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Università di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. isabella.lancellotti@unimore.it
Kamseu
Elie
E
Michelazzi
Marco
M
Barbieri
Luisa
L
Corradi
Anna
A
Leonelli
Cristina
C
D000535:Aluminum / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002947:Cities; D060729:Coal Ash; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D007616:Kaolin; D019216:Metals, Heavy / Q000737:chemistry; D052638:Particulate Matter / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D012037:Refuse Disposal; D012822:Silicon Dioxide / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013054:Spectrophotometry, Atomic; D013696:Temperature
D060729:Coal Ash; D019216:Metals, Heavy; D052638:Particulate Matter; D011108:Polymers; D012996:Solutions; D007616:Kaolin; D002244:Carbon; D012822:Silicon Dioxide; D012964:Sodium; D000535:Aluminum