Dissolution kinetics of clinoptilolite and heulandite in alkaline conditions

Cotton, Alissa

doi:10.1093/biohorizons/hzn003

Cited by 21 publications

(8 citation statements)

References 14 publications

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“…2 GPa, is reached and the structure undergoes a more substantial pressure induced amorphization. Assuming that the formation of an activated complex involving five-coordinate silicon through attack by an OH− group will be rate-determining (we find attack at aluminum to be more favorable by over 30 kJ mol −1 ), the best theoretical estimate is ∼35−45 kJ mol −1 , , similar to the measured value obtained here and the experimental value of 27.4 kJ mol −1 reported for the dissolution of the mineral heulandite . Measurements of the rate of dissolution made under different pH conditions show that the order of the dissolution process is 0.31 with respect to OH − , which is in close agreement with bulk measurements made on related mineral phases…”

Section: Resultssupporting

confidence: 82%

Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation

et al. 2010

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A molecular-scale understanding of crystal growth is critical to the development of important materials such as pharmaceuticals, semiconductors and catalysts. Only recently has this been possible with the advent of atomic force microscopy that permits observation of nanoscopic features on solid surfaces under a liquid or solution environment. This allows in situ measurement of important chemical transformations such as crystal growth and dissolution. Further, the microscope can access not only an accurate height measurement of surface topography, important to deduce structural elements, but also the forces involved during nanoscopic processes. We have discovered that it is possible to use these features to "illuminate" critical nanoscopic chemical events at crystal surfaces and at the same time extract the associated energies and unstitch the details of the stepwise mechanism of growth and dissolution. This approach has been developed using nanoporous crystals of the heterogeneous catalyst zeolite L; however, in principle the approach could be adapted to many crystal growth problems.

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Section: Resultssupporting

confidence: 82%

Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation

et al. 2010

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“…5 d). Since the pH zpc of CZ is 3, there is a positive charge on the surface of CZ at pHs below 3 43 – 45 . Therefore, at pHs lower than 3, the electrostatic repulsion between the positively charged metal and the positive charge on the adsorbent surface would reduce the lead removal rate.…”

Section: Resultsmentioning

confidence: 99%

RETRACTED ARTICLE: Optimization of dyes and toxic metals removal from environmental water samples by clinoptilolite zeolite using response surface methodology approach

Sun

Abbass²,

Ghoroqi

et al. 2022

Sci Rep

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The present study aimed to remove crystal violet (CV), malachite green (MG), Cd(II), and Pb(II) from an aqueous solution using clinoptilolite zeolite (CZ) as an adsorbent. Response surface methodology (RSM) based on central composite design (CCD) was used to analyze and optimize the process parameters, such as pH, analyte concentration, adsorbent amount, and sonication time. Quadratic models with the coefficient of determination (R2) of 0.99 (p < 0.0001) were compared statistically. The results revealed that the selected models have good precision and a good agreement between the predicted and experimental data. The maximum removal of contaminants was achieved under optimum conditions of pH = 6, sonication time of 22 min, the adsorbent amount of 0.19 g, and analyte concentration of 10 mg L−1. The reusability test of the adsorbent showed that the CZ adsorbent could be used 5 times in water and wastewater treatment processes. According to the results of interference studies, the presence of different ions, even at high concentrations, does not interfere with the removal of contaminants. Applying the CZ adsorbent on environmental water samples revealed that CZ adsorbent could remove CV, MG, Cd(II), and Pb(II) in the range of 84.54% to 99.38% and contaminants present in industrial effluents. As a result, the optimized method in this study can be widely used with high efficiency for removing CV, MG, Cd(II), and Pb(II) from water and wastewater samples.

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“…The framework with hydrolysed bonds becomes unstable. The weak parts detach and enter the solution [10] where they react with Ca 2+ and form hydrated calcium silicate and calcium aluminate compounds, very similar to those formed during the hydration of cement [9]. It is widely known that natural zeolites have a high pozzolanic activity.…”

Section: Introductionmentioning

confidence: 99%

Use of Natural Zeolite and Glass Powder Mixture as Partial Replacement of Portland Cement: The Effect on Hydration, Properties and Porosity

2022

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The study investigates effect of the additive consisting of natural zeolite (clinoptilolite) and soda lime glass powder on the hydration, mechanical properties and porosity of Portland cement concrete. The effect of mineral additive on the technological, physical-mechanical properties and porosity of the mortar was investigated by increasing the content of natural zeolite and glass powder added to the mortar up to 20% by weight of cement in increments of 5% and different particles size of natural zeolite. The mixes with the best technological and mechanical properties were identified and further studies were conducted by replacing 10% and 15% of cement with natural zeolite and soda lime glass with an average grain size of 59.3 μm, 29.0 μm or 3.6 μm of zeolite, and 29.6 μm of glass powder. The hydration process and microstructure of hardened cement paste modified with the aforementioned mineral additives was analysed by microcalorimetry, X-ray diffraction tests and thermogravimetric analysis. The optimal composition of cement paste and particle size distribution of natural zeolite were determined to achieve the higher flexural and compressive strength and lower open porosity. The mixture of mineral additives has the highest effect in terms of flexural and compressive strength and open porosity when added at the proportion 75:15:10 (cement:natural zeolite:soda lime glass) and when zeolite with an average particle size of about 3.6 μm is used

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Dissolution kinetics of clinoptilolite and heulandite in alkaline conditions

Cited by 21 publications

References 14 publications

Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation

Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation

RETRACTED ARTICLE: Optimization of dyes and toxic metals removal from environmental water samples by clinoptilolite zeolite using response surface methodology approach

Use of Natural Zeolite and Glass Powder Mixture as Partial Replacement of Portland Cement: The Effect on Hydration, Properties and Porosity

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