We
simulate a moving bed temperature swing adsorption (MBTSA) process
to capture CO2 in postcombustion context using zeolite
13X as adsorbent. Experimental adsorption isotherms for CO2 and N2 were performed gravimetrically to obtain the equilibrium
input data for the model. The need of the flue gas drying was demonstrated
by pure water and binary water/CO2 experimental adsorption
isotherms, and the energy penalty of the water removal was accounted
for within the energetic duty of the unit. The model consists of three
sections (adsorption, regeneration, and cooling) each with its own
model and integrated by a composite model that simulates the entire
unit. Given the large number of variables and parameters in a MBTSA
process, which can be arranged in different input data sets, a parametric
study of the effect of several variables (feed gas flow rate, regeneration
temperature, adsorbent residence time in the adsorption section, feed
temperature, solid loading) on the key performance parameters of the
process was performed. The results showed that, under the studied
conditions, values up to 99% and 91% mol of CO2 recovery
and purity could be achieved, respectively. The specific energy consumption,
which included an energy recovery in the cooling section, was found
to be competitive against reported values for commercial amine absorption
separation processes suggesting that the MBTSA process might be a
potential separation process candidate for large-scale postcombustion
CO2 capture by adsorption.
Zeolites are nanoporous alumina silicates in a framework with cations, exhibiting ion-exchange properties with metal ions making them possible antimicrobial materials. The aim of this study was to evaluate the antimicrobial activity of ion-exchanged zeolites and the toxic potential of these materials. Zeolite-Co2+ and Li+ exhibited the most effective inhibition on Staphylococcus aureus growth than in other microorganisms (Escherichia coli and Pseudomonas aeroginosa) in low concentrations. Zeolite-Cu2+ presented higher zone of inhibition when tested against Candida albicans, while Zeolite-Zn2+ showed similar effectiveness among all the microorganisms. When ion-exchanged zeolites were used in effective concentrations to achieve antimicrobial activity, no alterations against bioindicators organisms as Artemia sp. and L. sativa were found and, in addition, they have non-significant result in terms of DNA cleavage activity. Zeolites have advantage of releasing slowly the metals loaded and this characteristic can to be considered promising as potential antimicrobial materials in concentrations safe for use.
Lithium‐based zeolites are the most commonly used materials in PSA (pressure swing adsorption) oxygen concentration from atmospheric air. Synthesizing these adsorbents using mineral raw materials adapts to worldwide environmental requests, as only high‐purity chemical reactants such as aluminates and silicates are usually used. The present work aims to synthesize and characterize zeolites using kaolin as raw material by studying the influence of the metakaolinization temperature and SiO2/Al2O3 and H2O/Na2O molar ratios by experimental design. Ion exchange was used to incorporate lithium into synthesized zeolites. Kaolin was treated thermically and characterized, and zeolites were synthesized by a hydrothermal reaction. After synthesis, ionic exchange of Na+ ions by Li+ was performed. The results indicated the presence of three main phases, zeolites A, X, and P. Using ANOVA, it was found that the factors that contributed significantly to the formation of zeolite X were the H2O/Na2O and SiO2/Al2O3 molar ratios. For zeolite A, the major influence was by the metakaolinization temperature and for zeolite P none of the factors was influential. Zeolites that incorporated higher amounts of lithium showed higher N2 adsorption potential, indicating that even without pure phases formed, it was possible to obtain similar adsorption efficiency to commercial zeolite.
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