Clinoptilolite-zeolite

Fig. 23.6. Calculated saturation indices (log Q/K) of aluminum-bearing minerals plotted versus temperature for a hot spring water from Gjogur, Hveravik, Iceland. Lines for most of the minerals are not labeled, due to space limitations. Sampling temperature is 72 °C and predicted equilibrium temperature (arrow) is about 80 °C. Clinoptilolite (zeolite) minerals are the most supersaturated minerals below this temperature and saponite (smectite clay) minerals are the most supersaturated above it.

Physicochemical Properties of High Silica L and Clinoptilolite Zeolites... 

TTigh silica zeolites attract great attention since they are characterized by relatively high thermal stability and considerable acid resistance. Physicochemical properties of high silica zeolites, despite a number of investigations, have not been sufficiently studied. The same is true for L- and clinoptilolite zeolite. The data on synthesis, structure, adsorption properties, decationization, dealuminization, adsorption heats, and other properties of the above-mentioned zeolites have been given (1-15). Results of studies of physicochemical properties of L zeolites and of natural and modified clinoptilolite are given here. 

Zeolites have also proven applicable for removal of nitrogen oxides (NO ) from wet nitric acid plant tail gas (59) by the UOP PURASIV N process (54). The removal of NO from flue gases can also be accomplished by adsorption. The Unitaka process utilizes activated carbon with a catalyst for reaction of NO, with ammonia, and activated carbon has been used to convert NO to N02, which is removed by scrubbing (58). Mercury is another pollutant that can be removed and recovered by TSA. Activated carbon impregnated with elemental sulfur is effective for removing Hg vapor from air and other gas streams the Hg can be recovered by ex situ thermal oxidation in a retort (60). The UOP PURASIV Hg process recovers Hg from clilor-alkali plant vent streams using more conventional TSA regeneration (54). Mordenite and clinoptilolite zeolites are used to remove HQ from Q2, clilorinated hydrocarbons, and reformer catalyst gas streams (61). Activated aluminas are also used for such applications, and for the adsorption of fluorine and boron—fluorine compounds from alkylation (qv) processes (50). 

Clinoptilolite, Zeolite, Unit Cell Na,(AI02),(Si02)so 2413 0... 

In addition, they have potential applications as an additive in soils, for heavy metal adsorption [24] and as carrier in pesticides, herbicides and fungicides. Based on such adsorbing characteristics, zeolites have also been effective as additive in animal feeds to act as a detoxing agent, e.g., Clinoptilolite. Zeolites exhibit possibilities of applications in animal sheds for adsorbing hydrogen sulphides and subsequent odour control in the surrounding environment. 

Figure 4.13 Hydration stack over time of a zeolite-blended portland cement as measured by synchrotron radiation indicated are ettringite (AFt), monosulfate (AFm), clinoptilolite (zeolite Cli), portlandite (CH) and alite (C3S). (Reprinted from Cement and Concrete Research, 40, Snellings, R., G. Mertens, O. Cizer and J. Elsen (2010), Early age hydration and pozzolanic reaction in natural zeolite blended cements Reaction kinetics and products by in situ synchrotron x-ray powder diffraction, 1704-1713, Copyright 2010, with permission from Elsevier.)...

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