By means of an EPR investigation of Mo ions introduced into NaY zeolites by solid-state reactions, the location and coordination of Mo in zeolites were investigated. Two different locations, free and distorted tetrahedral, were found. The molecular orbital coefficient, ß, and the effective charge, Q, for the MO ions in a distorted tetrahedral structure were calculated and interpreted.

Fluoride in drinking water has a profound effect on teeth and bones. Up to a small level (1-1.5mg/L) this strengthens the enamel. Concentrations in the range of 1.5-4 mg/L result in dental fluorosis whereas with prolonged exposure at still higher fluoride concentrations (4-10mg/L) dental fluorosis progresses to skeletal fluorosis. High fluoride concentrations in groundwater, up to more than 30 ...

This study investigated whether zeolites of different size (Y30 (nano-sized) and H-Beta(OH)-III (forming large aggregates/agglomerates composed of 50 nm small primary particles)) exerted acute toxicity on larvae of the non-biting midge, Chironomus riparius, and whether such zeolites are able to modulate the toxicity of a common insecticide, thiacloprid, by means of adsorption of a dissolved tox...

Nearly all atoms contributing to the local structure of Bransted acid sites in zeolites exhibit isotopes accessible for multinuclear solid-state nuclear magnetic resonance (NMR) investigations. Therefore, in the last 15 years, NMR spectroscopy has found numerous applications for the determination of the types of hydroxyl proton in zeolites, of their concentration, accessibility, and mobility, a...

zeolites due to their structures can be used as molecular sieves for purification of materials and solutions. zeolites with phi and sod structure are so common and applicable for this purpose. hydroxy sodalite and phillipsite are the more abundant members of zeolites which display good selectivity for very small molecules and some ions such as sr, pb, zn, cu and rb. there is not any pure natura...

In this study, Response Surface Methodology (RSM) using Central Composite Design (CCD) was employed to optimize the conditions of independent variables (adsorption time and ion solution concentration) for the removal of Zinc (II) and Ag ions from the aqueous solutions using analcime and modified analcime zeolites (Fe-ANA and Ni-ANA) as efficient and low cost adsor...

South African fly ash has been shown to be a useful feedstock for the synthesis of some zeolites. The present study focuses on the effect of impeller design and agitation rates on the synthesis of zeolite Na-P1 which are critical to the commercialization of this product. The effects of three impeller designs (4-flat blade, Anchor and Archimedes screw impellers) and three agitation speeds (150, ...

nay zeolites with different framework si/al ratios were synthesized via hydrothermal technique. structural characteristics of the synthesized zeolites were determined by using xrd, xrf, sem, bet analyses. the effects of operating conditions of hydrothermal dealumination, i.e. time, temperature and partial pressure of water vapor on dealumination of the y zeolites framework and their structure w...

Four naturally occurring zeolites were examined to verify their assignments as chabazites AZLB-Ca and AZLB-Na (Bowie, Arizona) clinoptilolites NM-Ca (Winston, New Mexico) NV-Na (Ash Meadows, Nevada). Based on powder X-ray diffraction, was discovered be mostly quartz with some clinoptilolite residues. Treatment concentrated HCl (12.1 M) acid resulted in AZLB-Na, the chabazite-like species, becom...