Topic
Ettringite
About: Ettringite is a research topic. Over the lifetime, 2702 publications have been published within this topic receiving 67056 citations. The topic is also known as: woodfordite.
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TL;DR: In this article, the sorption of selenite and selenate to ettringite (3CaO x Al2O3 x 3CaSO4 x 32H2O), "monosulfate", and calcium silicate hydrate (C-S-H) was investigated in order to understand Se immobilization by cement in hazardous wastes.
Abstract: The sorption of selenite and selenate to ettringite (3CaO x Al2O3 x 3CaSO4 x 32H2O), "monosulfate" (3CaO x Al2O3 x CaSO4 x 12H2O), and calcium silicate hydrate (C-S-H) was investigated in order to understand Se immobilization by cement in hazardous wastes. Sorption kinetics were fast with equilibrium between the minerals and Se species reached within 1 d. Selenite is suggested to sorb by surface reactions, and for ettringite, a sorption maximum of 0.03 mol kg(-1) was determined. Distribution ratios (Rd) for selenite were 0.18, 0.38, and 0.21 m3 kg(-1) for ettringite, monosulfate, and C-S-H, respectively. At high selenite additions, CaSeO3 was precipitated with a solubility product of Kso = 10(-7.27) (I = 0, 25 degrees C). Selenate sorbed only weakly to ettringite (Rd = 0.03), and no significant sorption to C-S-H was found. In contrast, sorption to monosulfate was strong (Rd = 2.06). With increasing selenate addition, XRD analyses revealed changes in the interlayer distance of monosulfate, in parallel with an increase of the ettringite fraction. Substitution of sulfate is suggested to be the relevant process. This indicates that selenate is sorbed more efficiently by monosulfate-rich cement, while the cement composition is of minor importance for selenite sorption.
104 citations
TL;DR: Sulfate sorption on limestone seems to be an alternative to treating mine waters with sulfate concentrations below the 1200-2000mg/L range, where lime precipitation is not effective, and this approach does not require alkaline pH values, as in the ettringite process.
104 citations
TL;DR: Given the lack of complex precipitates, and relatively high solubility, gypsum crystallisation cannot practically be used to remove sulfate to very low levels, and gas-sulfide treatment will likely still be required.
104 citations
TL;DR: In this article, the authors investigated the properties of seawater for concrete manufacturing and showed that seawater can promote the early hydration of tricalcium silicate (C3S) during the hydration acceleration period.
104 citations
TL;DR: In this article, the authors investigated a cementitious material by utilizing two industrial wastes, phosphogypsum (PG) and steel slag (SS), combined with another industrial byproduct ground granulated blast-furnace slag and limestone (LS).
103 citations