Preparation, Modification And Application In Enviromental Treatment Of Geopolymer

The preparation, properties and microstructure of fly ash-based geopolymer modified by mineral materials and the application of geopolymers with cage-like structure in solidification of heavy metal ions and purification of formaldehyde vapor were investigated. The results showed that appropriate α-Al2O3addition favored the geopolymerisation and therefore increased the compressive strength; alkali-activating the mixture of fly ash and slag could obtain the composite cementitious material with excellent mechanical properties at ambient temperature; Ca-bentonite and5A zeolite addition could decrease the efflorescence extent while red mud addition had a negative effect on compressive strength. Fly ash-based geopolymer had a good effect for immobilizing heavy metal and zeolite addition improved the long term stability of immobilization; physical encapsulation was the main mechanism of immobilizing heavy metal with fly ash-based geopolymer. Geopolymers exhibited a certain ability for purifying formaldehyde and lower Si/Al ratio geopolymers had larger formaldehyde adsorption capacity. Increasing water/solid ratio, NaOH concentration, curing time and curing temperature promoted the conversion from geopolymer to zeolite. Zeolite-contained metakaolin-based geopolymers exhibited excellent ability of formaldehyde adsorption and it was characterized by low cost and wide adaptablity.