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Percorrer por autor "Chalghmi, Alia Balkis"

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  • Production of geopolymers from diatomaceous earth for wastewater treatment
    Publication . Chalghmi, Alia Balkis; Gomes, Helder; Triviño, Jose Luis Díaz de Tuesta; Zaghdoudi, Zaghdoudi
    Geopolymers (GPs) are inorganic binders created by adding an alkaline solution (e.g., NaOH) to silicates, such as furnace slags, fly ashes or clays, to dissolve Si and Al that polymerizes and precipitates to form an inorganic binder material while hardening. GP properties are similar to ordinary Portland cement, since it presents high compressive strength or low shrinkage, but they are particularly notable for a high resistance to acid and fire. For this reason, GP has been widely studied in its application in civil engineering. However, GPs presents other interesting properties that make it an excellent material to be used as adsorbent. The aim of this study is to investigate the suitability of commercial diatomaceous earth as a cheaper alternative to kaolin and to determine the necessary preparation steps required to produce effective geopolymer adsorbent materials. Geopolymerization is a multi-parameter system strongly influenced by the degree of activation, Si:Al ratio, amount of 5-fold coordinated Al and curing mode. Bearing this in mind, different formulations to yield geopolymeric solid samples were examined. Important parameters for the production, such as temperature, time, and heating rate are determined and discussed. Additionally, geopolymers were assessed in the removal of gallic acid and phenol, used as model pollutants, from aqueous solutions by adsorption. The results presented in this thesis indicate that commercial diatomaceous earth is a suitable raw material for geopolymer production. Proxies used to evaluate the optimal conditions for making geopolymers are determined including the Si/Al ratio as a key relationship that determines its ultimate hardness and curing mode as key factor that controls the geopolymerization process.
    2023Dissertação de mestrado Acesso aberto Ver mais