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Article

Mercury Removal from Aqueous Solution Using ETS-4 in the Presence of Cations of Distinct Sizes

1
CICECO, Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
2
QOPNA & LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
*
Authors to whom correspondence should be addressed.
Materials 2021, 14(1), 11; https://doi.org/10.3390/ma14010011
Received: 18 November 2020 / Revised: 15 December 2020 / Accepted: 18 December 2020 / Published: 22 December 2020
The removal of the hazardous Hg2+ from aqueous solutions was studied by ion exchange using titanosilicate in sodium form (Na-ETS-4). Isothermal batch experiments at fixed pH were performed to measure equilibrium and kinetic data, considering two very distinct situations to assess the influence of competition effects: (i) the counter ions initially in solution are Na+ and Hg2+ (both are exchangeable); (ii) the initial counter ions in solution are tetrapropylammonium (TPA+) and Hg2+ (only Hg2+ is exchangeable, since TPA+ is larger than the ETS-4 micropores). The results confirmed that ETS-4 is highly selective for Hg2+, with more than 90% of the mercury being exchanged from the fluid phase. The final equilibrium attained under the presence of TPA+ or Na+ in solution was very similar, however, the Hg2+/Na+/ETS-4 system in the presence of Na+ required more 100 h to reach equilibrium than in the presence of TPA+. The Hg2+/Na+/ETS-4 system was modelled and analyzed in terms of equilibrium (mass action law) and mass transfer (Maxwell–Stefan (MS) formalism). Concerning equilibrium, no major deviations from ideality were found in the range of studied concentrations. On the other hand, the MS based model described successfully (average deviation of 5.81%) all kinetic curves of mercury removal. View Full-Text
Keywords: ETS-4; ion exchange; kinetics; mercury; tetrapropylammonium hydroxide ETS-4; ion exchange; kinetics; mercury; tetrapropylammonium hydroxide
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MDPI and ACS Style

Cardoso, S.P.; Faria, T.L.; Pereira, E.; Portugal, I.; Lopes, C.B.; Silva, C.M. Mercury Removal from Aqueous Solution Using ETS-4 in the Presence of Cations of Distinct Sizes. Materials 2021, 14, 11. https://doi.org/10.3390/ma14010011

AMA Style

Cardoso SP, Faria TL, Pereira E, Portugal I, Lopes CB, Silva CM. Mercury Removal from Aqueous Solution Using ETS-4 in the Presence of Cations of Distinct Sizes. Materials. 2021; 14(1):11. https://doi.org/10.3390/ma14010011

Chicago/Turabian Style

Cardoso, Simão P., Tiago L. Faria, Eduarda Pereira, Inês Portugal, Cláudia B. Lopes, and Carlos M. Silva 2021. "Mercury Removal from Aqueous Solution Using ETS-4 in the Presence of Cations of Distinct Sizes" Materials 14, no. 1: 11. https://doi.org/10.3390/ma14010011

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