Synthesis and Characterization of Zeolites in the System Na₂O-K₂O-Al₂O₃-SiO₂-H₂O

Abstract

Abstraet--Zeolites having the structures of phillipsite, merlinoite, and gobbinsite were synthesized from clear solutions at 80~ in the system Na20-K20-Ai203-SiO2-H20 and their morphologies, cell parameters, and compositions determined. At 3.5 M silica concentration, the formation of merlinoite (synthetic zeolite W) is favored over the formation of phillipsite (synthetic zeolite ZK-19) by solution conditions of high pH (> 13.6) and low Na/(Na + K) ratios (<0.5).Using the information obtained from the synthesis experiments, the presence ofmerlinoite was predicted in sediments from Searles Lake, a saline, alkaline lake in California with ideal physiochemical conditions for its formation. Merlinoite was subsequently discovered to occur in tuffaceous sediments as part of an authigenic silicate zonation pattern from phillipsite -phillipsite + merlinoite ~ merlinoite ~ K-feldspar with increasing depth. Because of the close similarities in the physical properties of phillipsite and merlinoite, merlinoite may be much more common as an authigenic mineral than is currently realized.

Low Temperature Experimental Investigation of the Effect of High pH Naoh Solutions on the Opalinus Shale, Switzerland

“…Both zeolite and clay minerals have been synthesized using different starting materials and over a range of temperatures, solution compositions and pHs. Under high solution pH conditions similar to those expected in the cement-shale system, varying types of zeolites have been observed to grow and precipitate (Donahoe et al, 1984;Donahoe and Liou, 1985;Hawkins, 1981;van Aardt and Visser, 1977). Especially applicable to this study are those experiments conducted in the Na hydroxide systems (Barth-Wirshing and H/511er, 1989), where the starting material used was rhyolitic glass and the precipitation of analcime was observed.…”

Low Temperature Experimental Investigation of the Effect of High pH Koh Solutions on the Opalinus Shale, Switzerland

“…To further characterize the zeolite phase, a Guinier type camera was used. Distinguishing different types ofzeolites in mineral mixtures can be very difficult, and Donahoe et al (1984) describe in detail how to distinguish phillipsite from merlinoite using XRD. Results from observation with a Guinier type camera showed a characteristic phillipsite peak at ~4.15/k as well as the absence of a sharp 4.5/k zeolite peak indicative of merlinoite.…”

“…Focusing on the K dominant system, varying types of zeolites have been observed to grow and precipitate (Donahoe et aL, 1984;Donahoe and Liou, 1985;Hawkins, 1981;Hawkins et aL, 1978). Especially applicable to this study are those experiments conducted by Barth-Wirshing and H611er (1989) where their starting material was rhyolitic glass and Present address: Department of Geology, Georgia State University, 340 Kell Hall, Atlanta, Georgia 30303.…”

NPK Fertilizer With Slow Release Fly Ash

“…Both zeolite and fly ash contain Al 2 O 3 , SiO 2 , Fe 2 O 3 , CaO, and MgO which can be as super-absorbent with low cost of production. Zeolite usually used as fertilizer carrier and also fly ash according to the theory [6].…”