This study investigated the adsorption capacities and photocatalytic activities of geopolymer-zeolite composite materials by incorporating different amounts of zeolite and TiO 2 in a geopolymer matrix for dye removal. Geopolymers with SiO 2 /Al 2 O 3 molar ratio of 2.5 were synthesized from metakaolin. The geopolymers containing zeolite and TiO 2 -doped zeolite exhibited similar behavior in terms of mineral compositions, microstructures and chemical frameworks. The compressive strength of geopolymer-zeolite composite materials decreased with increasing amount of zeolite and TiO 2 -doped zeolite (0–40 wt%) because of the increase in the porosity of composite materials. The maximum methylene blue adsorption capacity and photocatalytic efficiency of the powdered geopolymer composites with 40 wt% TiO 2 -doped zeolite was 99.1% and was higher than that of the composites with 40 wt% zeolite without TiO 2 -doping (92.5%). In addition, the geopolymer composites with TiO 2 -doped zeolite exhibited excellent stability after repeated usage as photocatalysts. The adsorption capacity and photocatalytic activity of pelletized geopolymer composites decreased because of the reduction in their specific surface area.

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