Solid-state transformations of Zn-clinoptilolite through heating

Cerri, Guido; Brundu, Antonio

doi:10.1016/j.jssc.2019.121165

Cited by 4 publications

(3 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The result attained for M-Na is slightly lower and amounts 1.85 meq/g of Na + . On the other hand, the influence of pretreatment on capacity and selectivity of zeolites for metal ions is known (Semmens and Martin 1988 ; Pabalan and Bertetti 2001 ), and a preliminary exchange with sodium proved to be an effective procedure for obtaining homoionic Zn-clinoptilolite (Cerri et al 2004 ; Cerri and Brundu 2020 ). According to Pabalan and Bertetti ( 2001 ) and Colella ( 2005 ), the CEC of mordenite is comparable to that of clinoptilolite, therefore in M (as well as in M-Na and M-Zn ) most exchangeable cations are hosted by clinoptilolite since it is more abundant than mordenite.…”

Section: Resultsmentioning

confidence: 99%

Antibacterial activity of Zn-loaded Cuban zeolite against Helicobacter pylori in comparison to its Na-loaded and unmodified counterparts

Cerri

Farina

Brundu

et al. 2020

Environ Geochem Health

Self Cite

View full text Add to dashboard Cite

Helicobacter pylori can be found in the stomach of about half of the humans, and a large population can be associated with serious diseases. To survive in the stomach H. pylori increases the pH locally by producing ammonia which binds to H+ becoming ammonium. This work investigated the effects on the in-vitro growth of H. pylori of a natural cation-exchanger mainly composed (≈70%) of clinoptilolite and mordenite. The zeolitized material from Cuba was evaluated in its original form (M), as well as in its Na- (M-Na) and Zn-exchanged (M-Zn) counterparts. In the preliminary agar cup diffusion test, H. pylori revealed susceptibility only to M-Zn, with a direct relationship between concentration and width of inhibition halo. Further experiments evidenced that bacterium replication increases when ammonium is supplied to the growth medium and decreases when zeolites subtract NH4+ via ion exchange. Due to the multi-cationic population of its zeolites M was not effective enough in removing ammonium and, in the Minimum Inhibitory Concentration (MIC) test, allowed bacterial growth even at a concentration of 50 mg/mL. Inhibition was achieved with M-Na because it contained sodium zeolites capable of maximizing NH4+ subtraction, although the MIC was high (30 mg/mL). M-Zn evidenced a more effective inhibitory capacity, with a MIC of 4 mg/mL. Zinc has antimicrobial properties and H. pylori growth was affected by Zn2+ released from clinoptilolite and mordenite. These zeolites, being more selective towards NH4+ than Zn2+, can also subtract ammonium to the bacterium, thus enhancing the efficacy of M-Zn.

show abstract

Section: Resultsmentioning

confidence: 99%

Antibacterial activity of Zn-loaded Cuban zeolite against Helicobacter pylori in comparison to its Na-loaded and unmodified counterparts

Cerri

Farina

Brundu

et al. 2020

Environ Geochem Health

Self Cite

View full text Add to dashboard Cite

show abstract

“…Sometimes, the AmP obtained from a thermally treated clinoptilolite still shows a limited re-hydration ability, which is due to the remains of the zeolite channel system. Through this residual open microporosity, water molecules can diffuse; however, in this case, the weight gain—although limited—is fast (e.g., 1.57% in 24 h for amorphized Zn-clinoptilolite kept at room temperature and 50% RH [ 42 ]). The LoI values of Cs-C2 and Cs-C8 two days after preparation were 0.87 and 0.44% ( Table 2 ), which corresponded to the 44.6 and 27.5% of the hydration that was reached after almost six years (1.95 and 1.60%, respectively).…”

Section: Discussionmentioning

confidence: 99%

A Six-Year Hydration Evaluation of Cs-Bearing Materials at Room Temperature and 55% Relative Humidity Simulating Radioactive Waste with Different Crystallinities

Cerri,

Brundu

2024

Molecules

Self Cite

View full text Add to dashboard Cite

Radioactive wastes often contain amorphous and crystalline phases, and vapor hydration can affect their durability. In this study, Cs-clinoptilolite was heated (at 1100 °C and for 2–36 h) to prepare the samples that were composed mainly of an amorphous phase (AmP) and CsAlSi5O12 (≥94%) with minor CsAlSi2O6. Six samples with an AmP/CsAlSi5O12 ratio from 26.5 to 0.1 were kept at 21 °C and 55% relative humidity, and their hydration was measured via thermogravimetry (TG) over a period of almost six years. The hydration that resulted was directly related to the AmP quantity. The increase in water content followed a logarithmic trend over time. It reached 1.95% in the AmP-richest material, while it attained only 0.07% in the most crystalline sample. The hydrolysis of the AmP led to an increase over time in the tightly bound water. Samples with an AmP of ≤19% demonstrated slightly higher durability due to the lower Cs content in the AmP.

show abstract

“…In addition, the external area was characterized by a rounded edge and presented a more uniform appearance of a rusty red color, probably due to iron oxides. If the metal undergoes annealing after plastic deformation, the internal structural tensions are removed, and new grains grow with regular shape [41]. If the metallic sample is produced through melting and casting processes, during the cooling phase, micro-crystals form inside the liquid mass and around these, by growth, other atoms are added that involve the formation of large crystal grains [42].…”

Section: Iron Samplesmentioning

confidence: 99%

Microstructure, Chemistry and Mineralogy Approach for the Diagnostics of Metallic Finds of the Tomba della Biga (Adria, Italy)

et al. 2022

View full text Add to dashboard Cite

This work is focused on the characterization of metallic finds that are part of an ancient war biga from the Tomba della Biga, using different approaches for the diagnostics and also the conservation of this important cultural heritage. The materials analyzed were brought to light in the necropolis of Canal Bianco (Adria, Italy). The samples were analyzed using Optical Reflected Light Microscopy (ORLM), Scanning Electron Microscopy (SEM) and micro-Raman Spectroscopy (µ-RS). The results highlighted the occurrence of two different alloys (Fe and Cu-Sn-bronze) showing important structural and textural variations. These results, along with µ-RS, gave details on the surface and subsurface morphology, as well as the microstructures and the chemical and mineralogical composition of the finds. In particular, µ-RS highlighted the presence of magnetite and goethite as the main mineralogical phases for Fe-samples and malachite, azurite and Cu-oxide for bronze samples. In addition, an attempt was made to trace the manufacturing process, the purity of the alloys and the degree of slagging. Results of analytical studies show corrosion products of the samples which could be evidence of metallurgical aspects. The good state of conservation due to favorable conditions in the burial environment preserved the metal finds from intense corrosion, supporting the hypothesis that the samples reached equilibrium with soil during their life in the burial environment. This proposed methodology based on the microstructure, chemistry and mineral microanalysis allows the diagnostic and evaluation of the state of conservation of metallic finds.

show abstract

Solid-state transformations of Zn-clinoptilolite through heating

Cited by 4 publications

References 37 publications

Antibacterial activity of Zn-loaded Cuban zeolite against Helicobacter pylori in comparison to its Na-loaded and unmodified counterparts

Antibacterial activity of Zn-loaded Cuban zeolite against Helicobacter pylori in comparison to its Na-loaded and unmodified counterparts

A Six-Year Hydration Evaluation of Cs-Bearing Materials at Room Temperature and 55% Relative Humidity Simulating Radioactive Waste with Different Crystallinities

Microstructure, Chemistry and Mineralogy Approach for the Diagnostics of Metallic Finds of the Tomba della Biga (Adria, Italy)

Contact Info

Product

Resources

About