The removal of zinc ions by natural and conditioned clinoptilolites

Investigation on natural and pretreated Bulgarian clinoptilolite for ammonium ions removal from aqueous solutions

“…The exposure of the natural clinoptilolite to a NaCl solution leads to the production of the sodium-rich sample. Na-rich forms of clinoptilolite are known to have an enhanced exchange capacity, because also a part of the more tightly bound K and Ca cations are exchanged when treated with Na solutions [17,24]. It is clear that as the temperature of treatment with NaCl increases, the sodium content of the clinoptilolite increases in parallel and this increase is mainly attributed to the exchange of K + and Ca 2+ [24].…”

Adsorption of Ba2+ by Ca-exchange clinoptilolite tuff and montmorillonite clay

“…In the zeolite minerals the structural arrangements develop channels through which ions pass through or are adsorbed, retained or exchanged according with the characteristics and dimensions of channels and ions, hence defining the suitability of the zeolite for specific adsorptions [7]. Among the most common zeolites is clinoptilolite, which has been applied in its natural state or modified by HCl and NaCl treatments to the removal of Cr 3+ , Cu 2+ , Cd 2+ , Hg 2+ , Zn 2+ , Ni 2+ and Pb 2+ [8][9][10][11][12][13][14][15][16]. In the clay minerals, rings of SiO 4 and AlO 4 tetrahedra share oxygen atoms with Al(OH)O 4 octahedra to develop layered structures with internal active surfaces and edges on which ions are adsorbed.…”

Ni2+ removal from aqueous solutions using conditioned clinoptilolites: Kinetic and isotherm studies

“…The crystalline phase composition of the natural clinoptilolite used in this work was characterized by X-ray diffractometry (XRD; Rigaku, D/Max-IIIC) with Cu Ka radiation. As it can be seen from Figure 1, X-ray diffraction analysis showed that this material was almost 95% clinoptilolite (CaSi 7 Figure 1, the inner shards exhibit drusy textures. The size of the clinoptilolite crystals are generally 1-100 lm.…”