Geopolymer beads and 3d printed lattices containing activated carbon and hydrotalcite for anionic dye removal
Oliveira, Karine G.; Botti, Renata; Kavun, Vitalii; Gafiullina, Anastasiia; Franchin, Giorgia; Repo, Eveliina; Colombo, Paolo (2021-12-08)
Sisältö avataan julkiseksi: 09.12.2023
Post-print / Final draft
School of Engineering Science
In this work, the performance of geopolymer composites with the addition of activated carbon and hydrotalcite for the removal of an organic anionic dye (Orange II) from water was investigated. Beads produced by freeze-drying were compared with lattices produced by Direct Ink Writing. For both beads and lattices, the geopolymer matrix had the following molar ratios: SiO2/Al2O3 = 3.8; Na2O/Al2O3 = 1. H2O/Al2O3 ratio was adjusted to the different process. The different fillers were added to the slurries up to an amount of 27%wt (dry basis).
Beads were produced by dripping the slurries into a liquid nitrogen bath and by freeze-drying the resulting beads for two days; the geopolymerization was finally completed at 75 ºC and 100% relative humidity. The slurries prepared for Direct Ink Writing contained also sodium bentonite as a rheological agent to enhance the pseudoplasticity of the ink. The lattices were printed with a nozzle with a diameter of 840 µm and consisted of a 0º–90º stacking of layers of filaments with 0.8 mm spacing, which resulted in a design porosity of 50 vol%; the geopolymerization was completed at 75 ºC for 2 days and 100% relative humidity.
Physical and chemical characterizations were performed on both beads and lattices (porosity, morphology and crystallinity, compressive strength); the removal efficiency of Orange II dye was evaluated focusing on the adsorption capacity and kinetics.
Oliveira, K.G., Botti, R., Kavun, V., Gafiullina, A., Franchin, G., Repo, E., Colombo, P. (2021). Geopolymer beads and 3d printed lattices containing activated carbon and hydrotalcite for anionic dye removal. Catalysis Today. DOI: 10.1016/j.cattod.2021.12.002
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