부산대학교 도서관

In-situ crystallization of Cs-bearing zeolites (especially pollucite) is an efficient way to enhance Cs immobilization in geopolymers. This study investigated the amounts of in-situ pollucite crystallized at different curing times (up to 7 days) in the fly ash geopolymer (FA-GP) systems containing 20 wt.% cesium dosage and cured at 90 °C. Pollucite content was then associated with the degree of Cs immobilization (expressed through the leachability index LX) and other FA-GP properties, not previously reported. Investigation of the kinetics of in-situ pollucite crystallization was conducted at three temperatures (56, 73, and 90 °C) for varying curing times of up to 14 days, with an aim to determine the activation energy of the pollucite crystallization using JMAK model and Arrhenius equation. The results suggested a linear correlation of in-situ pollucite content with the Cs immobilization. Significantly high leachability index (LX) value ≥ 12 was achieved within 6 h of curing at 90 °C, implying effective Cs immobilization. Relatively low activation energy (Ea) of ~ 25 kJ/mol, not reported hitherto, for in-situ pollucite crystallization was found in our system, suggesting feasible crystallization of pollucite via one-step synthesis process, at relatively low temperatures. [ABSTRACT FROM AUTHOR]