Synthesis of zeolite-geopolymer composites via in-situ geopolymerization

Reference Presenter Authors
(Institution)
Abstract
04-092 ANDREIA DE ROSSI DE ROSSI, A.(Universidade Federal de Santa Catarina); Simão, L.(Universidade Federal de Santa Catarina); Ribeiro, M.J.(Instituto Politécnico de Viana do Castelo); Montedo, O.K.(Universidade do Extremo Sul Catarinense); Raupp-Pereira, F.(Universidade Federal de Santa Catarina); Novais, R.M.(Universidade de Aveiro); Labrincha, J.A.(Universidade de Aveiro); Hotza, D.(Universidade Federal de Santa Catarina); Moreira, R.d.(Universidade Federal de Santa Catarina); Geopolymers were initially idealized and extensively studied as building materials to replace Portland cement. Chemical composition and characteristics similar to zeolites boosted alternative applications. Zeolites are hydrated aluminosilicates of alkaline and alkaline earth metals with a porous crystalline structure and surface properties suitable for environmental applications. The synthesis of geopolymer matrix composites with zeolite crystals in their structure increases the potential for use in filtration membranes, combining the geopolymers’ mechanical strength and the high adsorption of the zeolites. In the present work, biomass ashes (75 wt%) and metakaolin (25 wt%) were alkali activated and cured for 28 days in a hermetic container at 60 oC to obtain zeolite-based geopolymers. Hydrogen peroxide (H2O2) was used as a porogenic agent (0.00, 0.15 and 0.30 wt%). The used activators were 10 M NaOH and sodium silicate (SiO2/Na2O = 3.15) in a 1:1 ratio. The solid/liquid ratio was 1.93 with SiO2/Al2O3 molar ratio of 4.54. X-ray diffractograms showed the presence of Faujasite zeolites independent of the added H2O2 content. Zeolite P was found in the formulation without porogenic agent. The composition with 0.15 wt% of H2O2 showed Faujasite diffraction peaks with higher intensity, with total porosity of 60 ± 2% and compressive strength of 7.2 ± 0.8 MPa. The identified zeolites suggest different applications, from the treatment of atmospheric emissions (adsorption of volatile organic compounds, CO2 capture) to the treatment of effluents (adsorption of toxic metals).
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