The Simultaneous Removal of Zinc and Cadmium from Multicomponent Aqueous Solutions by Their Sorption onto Selected Natural and Synthetic Zeolites

Natural and synthetic aluminosilicate minerals, in particular zeolites, are considered to be very useful in remediation processes, such as purification of waters polluted with heavy metals. That is due to their unique and outstanding physico-chemical properties, rendering them highly efficient, low-cost, and environmentally friendly sorbents of various environmental pollutants. The aim of this study was to examine the sorption capacity of four selected zeolites: A natural zeolite and three synthetic zeolites (3A, 10A, and 13X), towards zinc and cadmium present in multicomponent aqueous solutions, in relation to identified sorption mechanisms. It was stated that synthetic zeolites 3A and 10A were the most efficient in simultaneous removal of zinc and cadmium from aqueous solutions. Additionally, zeolite 10A was demonstrated to be the mineral best coping with prolonged pollution of water with those elements. The mechanism of sorption identified for tested minerals was physisorption.

Phase evolution of Na2O–Al2O3–SiO2–H2O gels in synthetic aluminosilicate binders

Nanostructural evolution of Na2O–Al2O3–SiO2–H2O gels in synthetic aluminosilicate binders investigated by solid state 29Si, 27Al and 23Na MAS NMR spectroscopy.

Thin section microanalysis of zeolite Y

Zeolite Y, a remarkably stable zeolite widely used in catalyst formulations, is a synthetic aluminosilicate with the faujaslte structure. It is distinguished from zeolite X by having fewer Al atoms per unit cell and greater stability. Y can be made even more stable by further reducing the number of Al atoms per unit cell to form ultrastable Y (U.S.Y). Because the Al/Si ratio of a zeolite is an important parameter affecting its properties, knowledge of the Al and Si distribution across individual particles is also important. A study of that distribution was therefore undertaken by electron microscopy. A catalyst preparation of 40% U.S.Y and 60% alumina was also analyzed.The samples were prepared for electron microscopy by embedding the particles in epoxy and cutting thin sections using an ultramicrotome. The thin section microanalysis was performed on a Philips 400T electron microscope equipped with a Tracor Northern TN2000 x-ray analyzer with digital beam control.