Quantum chemical study of the electronic structure of NA-X and NA-Y zeolites

Beran, S.; Dubský, J. V.

doi:10.1021/j100482a023

Cited by 68 publications

(12 citation statements)

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“…At longer times (stage II) and due to the Na + ion release, zeolite frameworks might have become unstable, especially in such high acidic solution, and suffered structural alteration with partial decay in the form of some silicon and aluminum cation evolution into the media. Under such conditions, the combined interaction of released Na + ions with the dissociated Si and Al were likely to precipitate an amorphous layer of sodium aluminosilicate on zeolite surfaces to protect and prevent more Na + ion release from zeolite assemblies and reached the steady-state release (Munthali et al 2015 ; Nagy et al 2011 ; Beran and Dubsky 1979 ). The whole zeolite dissolution profile can be seen in the light of the instability of their aluminosilicate structure in acidic media (Kuronen et al 2000 ; Wilkin and Barnes 1998 ).…”

Section: Resultsmentioning

confidence: 99%

Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

et al. 2019

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Three types of oral administrated micronized zeolites [ZSM-5, zeolite A and Faujasite NaX (ZSM-5, ZA and ZX, respectively)] were prepared as anticancer 5-fluorouracil (5-Fu) delivery systems for colon cancer treatment. They were prepared by economically widespread and cheap natural resource, kaolin, at low temperatures, using microwave advanced tool. The obtained powders were characterized by XRD, SEM/EDX and BET; meanwhile, their degradation was investigated in two gastric fluids; FaSSGF (pH 1.6) and FeSSGF (pH 5), through concentration measurement of their solution disintegrated elemental constituents of Na + , Al 3+ and Si 4+ ions. Also, the processes of drug release and mechanism in both solutions were investigated. Moreover, the inhibition action of 5-Fu-free and 5-Fu-conjugated zeolites on colon cancer cells (CaCo-2) was estimated. The results showed that, the prepared zeolites possessed high surface areas of 526, 250, and 578 m 2 /g for ZSM-5, ZA and ZX, respectively. Although, zeolite structures seemed significantly stable, their frameworks seemed more likely reactive with time. The ions and drug release for zeolites occurred in successively two stages and found to be pH dependent, where the drug and zeolite ions were significantly of higher values in the more acidic media of the gastric solution (pH 1.6) than those of the mild acidic one (pH 5). The obtained activity indicated no cytotoxic affinity for all the prepared zeolite types. Accordingly, the synthesized zeolite frameworks are proposed to be of strong potential drug delivery vehicle for the treatment of gastrointestinal cancer. Graphical abstract

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Section: Resultsmentioning

confidence: 99%

Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

et al. 2019

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“…The strong adsorption selectivity of mordenite for Cs + and Lindetype A for Sr 2+ can be explained by looking at the differences in their ionic diameters, the CEC values of the zeolites [36], and apertures (pore opening size) of the zeolites (Linde-type A: 11.4Å, 6.6Å, 4.1Å and 2.2Å; mordenite: 7.0Å, 4.2Å and 3.6Å [20,35,42,43]. The adsorption selectivity of Sr 2+ by the zeolites had positive correlation to the CEC.…”

Section: Cs + Adsorptionmentioning

confidence: 99%

Cs⁺and Sr²⁺adsorption selectivity of zeolites in relation to radioactive decontamination

Munthali

Johan

Aono

et al. 2015

Journal of Asian Ceramic Societies

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Zeolites are used as adsorbents of cationic elements in the radioactive decontamination process of water, soil and others. We determined Cs + and Sr 2+ adsorption selectivity of some zeolites to know effective zeolite species for the decontamination of radioactive Cs and Sr. A 30 mL mixed solution containing up to 15 mg L −1 of non-radioactive Cs + or Sr + and up to 0.50 M of Na + or K + was mixed with 0.5 g of Lindetype A, Na-P1, faujasite X, faujasite Y and mordenite. Among the zeolites, mordenite had the highest Cs + adsorption selectivity, and the selectivity had no correlation to the cation exchange capacity (CEC) of the zeolites. In contrast, Sr 2+ adsorption selectivity of the zeolites positively correlated with the CEC of the zeolites; Linde-type A with the highest CEC showed the highest adsorption selectivity, and its adsorption rate was more than 99.9% even in the presence of 0.5 M K +. A simulated soil decontamination experiment of Cs from a Cs-retaining vermiculite by using mordenite and that of Sr from a Sr-retaining vermiculite by using Linde-type A showed decontamination rates of more than 90%.

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“…Short separation distances means that two cations are located close to each other, which is unfavorable because of their electrostatic repulsion. Protons are not really bound like a cation, but are in covalent form [27] and do, therefore, not undergo such a strong electrostatic repulsion with neighbouring cations.…”

Section: Resultsmentioning

confidence: 99%

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

et al. 2014

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In addition to their well-known uses as catalysts, zeolites are utilized to adsorb and remove various cations from aqueous system. The adsorption of the cations is ascribed to the negative charge of zeolites derived from isomorphous substitution of Si by Al. The amount of Na+ adsorption on 4A, X, Y, Na-P1 and mordenite type zeolites were determined in aqueous media, in a two-cation (Na+ and H+) system. Although each zeolite has a constant amount of negative charge, the amount of Na+ adsorption of each zeolite decreased drastically at low pH-pNa values, where pH-pNa is equal to log{(Na+)/(H+)}. By using the plot of the amount of Na+ adsorption versus pH-pNa, an index of the H+ selectivity, which is similar to the pKa of acids, of each zeolite was estimated, and the index tended to increase with decreasing Si/Al ratio of zeolites. These indicate that zeolites with lower Si/Al and higher negative charge density have higher H+ adsorption selectivity, and in fact, such a zeolite species (4A and X) adsorbed considerable amount of H+ even at weakly alkaline pH region. The adsorption of H+ results in the decrease of cation adsorption ability, and may lead to the dissolution of zeolites in aqueous media.

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Quantum chemical study of the electronic structure of NA-X and NA-Y zeolites

Cited by 68 publications

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Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

Cs⁺and Sr²⁺adsorption selectivity of zeolites in relation to radioactive decontamination

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

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Quantum chemical study of the electronic structure of NA-X and NA-Y zeolites

Cited by 68 publications

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Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

Different zeolite systems for colon cancer therapy: monitoring of ion release, cytotoxicity and drug release behavior

Cs+and Sr2+adsorption selectivity of zeolites in relation to radioactive decontamination

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

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Cs⁺and Sr²⁺adsorption selectivity of zeolites in relation to radioactive decontamination