AFM imaging of the surface of natural heulandite

Exchange and reduction of Cu2+ ions in clinoptilolite

“…This led to the conclusion that besides ion exchange, other processes take place, such as copper precipitation in the form of a low-solubility phase and/or salt adsorption, that increase the amount of removed copper. Numerous studies are available in the literature on the occurrence of these processes during ion exchange, mainly the precipitation of low-solubility phases [19,21,[31][32][33]. In our case, the precipitation can be explained by the presence of OH − groups retained (adsorbed or occluded) on the zeolitic phase, which are liberated during the ion exchange so that their reaction with Cu 2+ ions take place, producing copper precipitation, probably as copper(II) hydroxide.…”

Crystal Growth Study of Nano-Zeolite by Atomic Force Microscopy

“…The outer surface of this zeolite investigated by AFM (Binder et al 1996) has also revealed growth spiral at screw dislocation with the pitch of ~9 Å (sometimes double), which is consistent with the bdimension of the zeolite. Further AFM works on heulandite (Yamamoto et al 1998) crystals has revealed the presence of steps, suggesting a possible birth-and-spread mechanism. The precipitated sodium aluminosilicate hydrogel has also been analyzed by AFM (Kosanovic et al 2008).…”

Iron Modified Natural Zeolite as Sustainable Environmental Catalysts: Correlation between Iron Speciation and Catalytic Activity in NO-Reduction

“…This could be explained by a reaction of exchanged iron cations with atmospheric oxygen and OHgroups retained (adsorbed or occluded) in the zeolite pores, which are liberated during the ion exchange. Numerous studies are available in the literature on the occurrence of these processes, mainly during ion exchange [32][33][34][35][36]. Also, Fe 3+ hydrolysis is expected to occur to a greater extent than that of Fe 2+ [37,38].…”