Synthetic hydrotalcite-type and hydrocalumite-type layered double hydroxides for arsenate uptake

Grover, Kanchan; Komarneni, Sridhar; Katsuki, Hiroaki

doi:10.1016/j.clay.2010.03.017

Cited by 79 publications

(28 citation statements)

References 25 publications

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“…The calculated basal spacings (i.e., 9.10 Å and 8.90 Å for H2AsO4 − and HAsO4 2− , respectively) are consistent with some of the reported experiments [31,80] that are conducted under initial pH around 7 and 8 (range from 8.71 Å to 9.21 Å, Figure 3) at a Mg/Al ratio of 2:1, while large differences are found between our simulations and the other experiments [8,76] conducted under pH of 5 or higher than 9 (<8.48 Å, Figure 3 [47]. This agreement validates our simulation set up.…”

Section: Basal Spacingsupporting

confidence: 90%

“…H 2 AsO 4 − and HAsO 4 2− co-exist at near-neutral pH conditions and they both occurred in the experimental systems [31], so the basal spacings for As(V) are presented together in Figure 3. The calculated basal spacings (i.e., 9.10 Å and 8.90 Å for H 2 AsO 4 − and HAsO 4 2− , respectively) are consistent with some of the reported experiments [31,80] that are conducted under initial pH around 7 and 8 (range from 8.71 Å to 9.21 Å, Figure 3) at a Mg/Al ratio of 2:1, while large differences are found between our simulations and the other experiments [8,76] conducted under pH of 5 or higher than 9 (<8.48 Å, Figure 3 The basal spacing values of As LDHs with low layer charge densities from experiments are significantly smaller than those from our simulations, but they coincide with those of NO3 − -LDHs (~8.0 Å at 4:1 and 8.04 Å-9.0 Å at 3:1 [47]). This implies that these species may not enter the gallery spaces of LDHs in some experiments, that is, the systems measured by those experiments are in fact still NO3 − -LDHs.…”

Section: Basal Spacingsupporting

confidence: 90%

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Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

Zhang¹,

Liu²,

Zhang³

et al. 2017

Minerals

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Abstract:In this study, by using first principles simulation techniques, we explored the basal spacings, interlayer structures, and dynamics of arsenite and arsenate intercalated Layered double hydroxides (LDHs). Our results confirm that the basal spacings of NO 3 − -LDHs increase with layer charge densities. It is found that Arsenic (As) species can enter the gallery spaces of LDHs with a Mg/Al ratio of 2:1 but they cannot enter those with lower charge densities. Interlayer species show layering distributions. All anions form a single layer distribution while water molecules form a single layer distribution at low layer charge density and a double layer distribution at high layer charge densities. H 2 AsO 4 − has two orientations in the interlayer regions (i.e., one with its three folds axis normal to the layer sheets and another with its two folds axis normal to the layer sheets), and only the latter is observed for HAsO 4 2− . H 2 AsO 3 − orientates in a tilt-lying way. The mobility of water and NO 3 − increases with the layer charge densities while As species have very low mobility.Our simulations provide microscopic information of As intercalated LDHs, which can be used for further understanding of the structures of oxy-anion intercalated LDHs.

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Section: Basal Spacingsupporting

confidence: 90%

Section: Basal Spacingsupporting

confidence: 90%

Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

Zhang¹,

Liu²,

Zhang³

et al. 2017

Minerals

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“…In general, Mg, Ca, and Al sources in raw GGBFS lead to the formation of hydrotalcite (Mg-Al LDH) and hydrocalumite (Ca-Al LDH) in alkali-activated GGBFS [39]. Both hydrotalcite and hydrocalumite have LDH structures with interlayered anions, which can be exchanged with chloride ions [40,49]. In the present study, Figure 4b illustrates the formation of Cl-exchanged hydrotalcite (i.e., Cl-hydrotalcite) and Cl-exchanged hydrocalumite (i.e., Cl-hydrocalumite) in the SSW sample.…”

Section: Xrd For the Ssw Samplementioning

confidence: 99%

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Jun

Yoon

2017

Applied Sciences

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Featured Application: The results of this study can be applied to the production of cementless concrete using seawater.Abstract: This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This study also examined the progressive changes in the pore structures of the FSW and SSW samples over time. The results show that the SSW sample is significantly more effective in the uptake of chloride ions compared to the FSW sample at 28 days of curing. While the FSW sample forms Cl-bearing zeolites (Cl-chabazite and Cl-sodalite) (possibly with similar types of geopolymeric gels), the SSW sample synthesizes Cl-bearing, layered double hydroxides (LDH) (Cl-hydrocalumite and Cl-hydrotalcite). Although both samples involve Cl-binding phases, the FSW sample is likely to be less efficient because it largely produces zeolites (or similar geopolymeric gels) with no Cl-binding capability (i.e., zeolites X and Y). Meanwhile, the SSW sample produces Cl-bearing LDH phases as well as C-S-H(I), which can physically adsorb chloride. The SSW sample exhibits both pore-size refinement and porosity reduction over time, while the FSW sample only exhibits pore-size refinement. Therefore, the SSW system is more advantageous in the use of seawater because it more effectively prevents Cl ingression due to greater impermeability.

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“…The low intensity of hydrotalcite and hydrocalumite reflections indicates not only low abundance but also the low degree of crystallization of these mineral phases [49]. These LDH mineral phases are formed as a result of the slaking process and identification and characterization is crucial due to their very high ability to fix carbonate anions [68]. During the rehydration process, CO 3 2− from the partial washing of unburnt fragments of limestone is fixed in the crystalline structure of HT-like minerals.…”

Section: Resultsmentioning

confidence: 99%

Hydrotalcite and Hydrocalumite in Mortar Binders from the Medieval Castle of Portilla (Álava, North Spain): Accurate Mineralogical Control to Achieve More Reliable Chronological Ages

et al. 2018

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Abstract:Mortars from different stratigraphic units at Portilla Castle (Alava, North Spain) have been analyzed for mineralogical characterization before radiocarbon dating. The mortar binder at Portilla Castle is composed not only of neoformation calcite but also of double-layered hydroxide (LDH) minerals such as hydrotalcite and hydrocalumite. The mineralogy of several fractions of the binder has been analyzed to determine the granulometric distribution of minerals in the binder. The continuous monitoring of mineralogy during the extraction of different grain size fractions has been performed by using a scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analyses (TGA). Hydrotalcite and hydrocalumite-bearing mortar binders give older ages than expected since they introduce dead carbon into the system.

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Synthetic hydrotalcite-type and hydrocalumite-type layered double hydroxides for arsenate uptake

Cited by 79 publications

References 25 publications

Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Hydrotalcite and Hydrocalumite in Mortar Binders from the Medieval Castle of Portilla (Álava, North Spain): Accurate Mineralogical Control to Achieve More Reliable Chronological Ages

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