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natural Zeolite ”, International Journal of Recycling ofOrganic Waste in Agriculture 1 ( 2012 ) 2 [9] S. Hassanpour Aslania , H. Ghafourianb

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some physical properties of soil and plant root growth 1998 Ayan, S. (2001): Utilization of zeolite as plant growing media

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Abstract  

The paper presents research results on dehydration properties and thermal behaviour of zeolites synthesized from fly ash, applying TG (thermogravimetry), DTG (derivative thermogravimetry) and SDTA (simultaneous differential thermal analysis) methods. In result of the analysis conducted water contents in zeolite samples were defined. On the basis of the data obtained from the thermogravimetric analysis, thermal behaviour of zeolites was assessed.

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Acta Veterinaria Hungarica
Authors:
Benjámin Kövesi
,
Szabina Kulcsár
,
Mátyás Cserháti
,
Márta Erdélyi
,
Zsolt Ancsin
,
Erika Zándoki
,
Miklós Mézes
, and
Krisztián Balogh

aflatoxin B 1 ( Fouad et al., 2019 ). Among them, mycotoxin absorbents, such as charcoal ( Yamauchi et al., 2014 ), zeolite and bentonite ( Prasai et al., 2018 ) and calcium aluminosilicates ( Chen et al., 2014 ) can prevent the absorption of aflatoxins

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Journal of Thermal Analysis and Calorimetry
Authors:
M. Földesová
,
P. Lukáč
,
P. Dillinger
,
V. Balek
, and
S. Svetík

Abstract  

Zeolites chemically modified with 1, 4 or 6 M aqueous solutions of NaOH were studied by DTA, TG and ETA (emanation thermal analysis) in the temperature range 201–200°C. The structural changes in the modified zeolites at room temperature and in the modified zeolites annealed at 1000°C were studied by XRD analysis. Thermal analysis demonstrated dehydration, dehydroxylation, structural changes and a glass transition. A gradual loss in crystallinity of the chemically modified zeolites was also observed. XRD analysis revealed structural changes caused by chemical treatment and also by annealing.

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A new zeolite derivative has been prepared by interacting Th(IV) and complexone in HCl medium and neutralising with aqueous ammonia. The amorphous and siliceous derivative showed a total mass loss of 29.25% in TG for stepwise dehydration, dehydroxylation and decomposition. Heats of reaction were 1167.6 J g−1 at 88.7°C and 75.167 J g−1 at 492.5°C for loss of volatile components and decomposition respectively.29Si and27Al MAS NMR spectra as well as XRD data of the derivative before and after calcination indicate presence of both four-coordinated and six-coordinated Al in varying ratios and the total loss of crystallinity.

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Summary  

The pozzolanic reactivity of thermally treated zeolites was studied on the basis of the Chapelle test combined with X-ray diffraction (XRD) and Fourier Transform (FTIR) spectroscopy, as well as thermogravimetric analysis (TG/DTG) and differential thermal analysis (DTA). The raw zeolite samples are from the Pentalofos area, Thrace, NE Greece. Their main mineral constituent is 'heulandite type-II', an intermediate type of the heulandite-clinoptilolite isomorphous series. Calcination of the samples was carried out up to 400, 500, 600, 700 and 1000C for 15 h. The changes were recorded using the above methods. The deformation of the zeolite crystal lattice starts at about 400C and proceeds as the temperature of thermal treatment rises. The thermal treatment of zeolite at 400C improves its pozzolanic reactivity and accelerates the reaction with Ca(OH)2.

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Journal of Thermal Analysis and Calorimetry
Authors:
D. Sternik
,
P. Staszczuk
,
M. Majdan
,
A. Gładysz-Płaska
,
E. Dąbrowska
, and
K. Bigda

Abstract  

The paper presents physico-chemical properties of mixed adsorbents in the clinoptylolite (mordenite)/SiO2 system containing 30, 50, 80 mass% zeolite. Adsorption capacity towards polar (water, butanol) and non-polar (n-octane) substances as well as total surface heterogeneity (energetic and geometrical) were determined. Desorption energy distribution functions as well as fractal dimensions were also determined and compared with the low-temperature nitrogen adsorption data. Irregular shapes of the curves q=f(E d) as well as large values of volumetric fractal dimensions (D f~2.6) revealed heterogeneous properties of the zeolite/SiO2 system surfaces. Addition of zeolite increases total heterogeneity of the material.

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Abstract  

Zeolite-4A is a hydrated aluminosilicate which becomes more hydrated when exchanged with transition metals. In this work, the dehydration kinetics of cobalt, nickel and copper(II)-exchanged zeolite-4A were studied by means of TG and DTA over the temperature range from 20 to 500C, and the numbers of water molecules in the metal-exchanged zeolite samples were calculated. It was observed that, as the ionic radius of the hydrated metal increased, the number of water molecules also increased. The loss of water from the zeolite samples generally occurred in the temperature range 100–300C and was manifested in the DTA graphs by an extended endothermic effect. The DTA curves demonstrated that the peak position shifted towards lower temperatures as the metal concentration increased or, in other words, the water of hydration increased. The kinetic parameters (order of reaction and activation energy) were calculated via the Coats and Redfern method. The process of dehydration was found to follow first-order kinetics.

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Abstract  

Sulphate resistance and passivation ability of the mortars made from pozzolan cement of CEM IV/A (P) type according to European Standard EN 197-1 (zeolite blended cement with 60.82 mass% of PC clinker, 35.09 mass% of zeolite and 4.09 mass% of gypsum abbreviated as ZBC) and ordinary Portland cement (abbreviated as PC) are introduced. Resistance tests were performed in water and 5% sodium sulphate solution (both 20°C) for 720 days. The increased sulphate resistance of pozzolan cement relative to that of PC was found. The key quantitative insight into the hydrate phase behaviour is given by thermal analysis. This is due to pozzolanic reaction of zeolite with PC resulting in reduction of the formed Ca(OH)2 opposite to the reference PC. Ability of pozzolan cements with 15 to 50 mass% of zeolite to protect steel against corrosion was verified in 20°C/85% RH-wet air within 180-day cure. Steel was not corroded in the mortars made with pozzolan cement containing up to 35 mass% of zeolite. Pozzolan cement of CEM IV/A (P) type containing 35 mass% of zeolite is a suitable cementitious material for concrete structures exposed to sulphate attack. Steel is protected against corrosion by this pozzolan cement in the same measure as the reference PC.

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