the capacity of natural zeolites to absorb anionic pollutants from water is limited. this limitation can be overcome by modifying the surface of the minerals with organic cations. in this research, natural zeolite, analcime was used for removing the nitrate and nitrite impurities from aqueous solutions. the surface of the zeolite was modified by tetramethylammonium and tetraethylammonium ions t...

Zeolites have been increasingly used in various application areas such as industry, agriculture, environmental protection, and even medicine. Although, there are no certain figures on the total amount of these minerals the world, some countries e.g. Cuba, USA, Russia, Japan, Italy, South Africa, Hungary and Bulgaria, have important reserves and production potentials. According to reports of 200...

Hierarchical clinoptilolite and L zeolites are prepared using optimized tandem dealumination-desilication treatments. The main challenge in the post-synthetic modification of these zeolites is the high Al content, requiring a tailored dealumination prior to the desilication step. For natural clinoptilolite sequential acid treatments using aqueous HCl solutions were applied, while for L a contro...

Chromatographic properties of different types of synthetic zeolites and samples of natural mordenite, modified by ion-exchange have been studied. The influence of degree of replacement and character of cations of alkali and alkaline-earth metals and also of silver and copper on chromatographic retainment of constant components of air and its most spread pollutants have been shown. Recommendatio...

The photochemistry of dibenzyl ketone and its derivatives has been employed to investigate the ability of zeolite molecular sieves to modify and to control the reaction channels available to organic molecules adsorbed on the internal and external zeolite surfaces. It is found that the observed photochemistry is very sensitive to the size/shape characteristics of the substrate ketones and of the...

Zeolites have been increasingly used in various application areas such as industry, agriculture, environmental protection, and even medicine. Although, there are no certain figures on the total amount of these minerals the world, some countries e.g. Cuba, USA, Russia, Japan, Italy, South Africa, Hungary and Bulgaria, have important reserves and production potentials. According to reports of 200...

We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their ...

We study the background associated with phenomena observed in zeolites using combinatorial and geometric techniques. We define combinatorial d-dimensional zeolites and show that not all combinatorial zeolites have a unit distance realization inR , and of those that have a unit distance realization, not all have non-overlapping unit-distance realizations. Only few classes of finite 2-d zeolites ...

The direct experimental evidence shows that ethylbenzene disproportionation is a transition state shape selective reaction on zeolites: a bimolecular reaction mechanism via diphenylethane-mediated pathway on large-pore zeolites X and Y (ca. 0.74 nm) and a monomolecular reaction mechanism on medium-pore zeolites ZSM-5 (ca. 0.56 nm) via the ethoxy-mediated intermolecular ethyl group transfer. The...