Hydrothermal synthesis of ammonium illite

Abstract

Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illitesmectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300 ЊC. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH 4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

High-temperature ammonium white mica from the Betic Cordillera (Spain)

“…5), which appear at positions similar to those described for tobelite (Higashi 1982), synthetic tobelite (Sucha et al 1998;Harlov et al 2001b), and synthetic NH 4 -phlogopite (Harlov et al 2001a). This method permits the identification of NH 4 -bearing mica even in samples with little present.…”

“…Nevertheless, the available DTA curves (e.g., Higashi 1982) indicate that loss of NH 4 begins at approximately 550 °C, and tobelite must be, theoretically, stable in metamorphic rocks below this temperature. Indeed, tobelite and its analogous trioctahedral mica have been synthesized at relatively high temperatures (up to 550 °C) (Eugster and Munoz 1966;Boss et al 1988;Sucha et al 1998;Harlov et al 2001aHarlov et al , 2001b. Surprisingly, high-temperature, ammonium-rich white mica had not been previously described, this in spite the fact that high NH 4 contents (up to 3000 ppm) have been measured in micas of various metamorphic grades (Honna and Itihara 1981;Itihara and Suwa 1985;Duit et al 1986;Visser 1992;Boyd and Philippot 1998;Mingram and Braüer 2001).…”

Ammonium loss and nitrogen isotopic fractionation in biotite as a function of metamorphic grade in metapelites from western Maine, USA

“…NH þ 4 released from organic matter during diagenesis may be incorporated into clay minerals and substitute for K + on the interlayer site in illite (e.g. Hallam and Eugster, 1976;Baxby et al, 1994;Williams et al, 1989;Sucha et al, 1998). Consequently, the concentration of ammonium depends on the availability and the fixing capacity of minerals (Williams et al, 1992;Schroeder and Ingall, 1994).…”

Illite-supported nanoscale zero-valent iron for removal of 238U from aqueous solution: characterization, reactivity and mechanism

“…6b. For instance, the characteristic absorption peaks of I-nZVI at 881, 726, 582 and 515 cm -1 , corresponding to Al-O-Si, Al-O, Si-O-Al and Si-O vibration, are significantly reduced [41,42]. The strong band at 1078 cm -1 assign to Si-O-R stretching vibration are also reduced, which is due to cation R on illite of I-nZVI replaced by UO 2 2?…”