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Application of Molecular Sieve Zeolites to Pollution Abatement
Published in Calvin Calmon, Harris Gold, Richard Prober, Ion Exchange for Pollution Control, 2018
During the same time period, exploratory tests were made of other zeolites. It was discovered16 that zeolites of the LINDE W-phillipsite-gismondine group provide superior NH4+ exchange characteristics in tests in simulated secondary effluents, even though these zeolites have lower maximum cation exchange capacities compared to the LINDE F zeolite.
Mechanical and microscopic properties of alkali-activated fly-ash-stabilised construction and demolition waste
Published in European Journal of Environmental and Civil Engineering, 2023
Lihua Li, Haoqi Zhang, Henglin Xiao, Yaoyao Pei, Jinzhong Wang
The diffraction pattern of FA appears broad and wide ‘drum peak’ within the range of 15°–35° (2θ), signifying the existence of a typical amorphous phase. The ‘drum peak’ of the diffraction pattern of the mixture reduces after the alkaline activation occurs, probably caused by two reasons. The first reason could be the dilution of the construction waste soil, whereas the second reason could be the occurrence of alkaline activation reaction, which consumes the amorphous phase. The activation reaction also causes the peaks of these ridges to shift to the right, roughly between 20° and 40° (2θ), which represents the formation of hydrated calcium aluminosilicate (C-A-S-H) and hydrated sodium aluminosilicate (N-A-S-H) in the amorphous phase (Kamilla et al., 2010). At the same time, the XRD analysis detected the presence of orthorhombic calcium zeolite (Gismondine; chemical formula is CaAl2Si2O8H2O; structural formula is CaOAl2O32SiO24H2O). However, hydrated aluminosilicate was not detected; the reason may be that its amount was too small to be detected. It is mentioned in the literature (Hui et al., 2005; Wang et al., 2008; Williams & Roberts, 2009) that the zeolite phase is converted from the C, N-A-S-H gel of the amorphous phase.
Analysis of particle size distribution of landfill contaminated soils and their mineralogical composition
Published in Particulate Science and Technology, 2020
Joan Nyika, Ednah Onyari, Megersa Dinka, Shivani Mishra
XRD results of various minerals in soils, their compound name, and chemical formula are shown in Table 3. All sampled soils had quartz. Mineral phases of anorthite, mica, halloysite, tosudite, rutile, ilmenite, albite, clinochrysotile-2Mc1, goethite gismondine, kalonite-A, despujolsite, and faujasite were also identified. The majority of sampling sites had primary minerals containing silicates, oxides of Fe, P, and Ti such as quartz, halloysite, goethite, ilmenite, and anorthite, which are ubiquitous minerals, resistant to weathering, thereby promoting the dissolution of other minerals (Kamau 2009). Secondary minerals containing aluminosilicate oxides, hydroxides and carbonates were also identified. Some soil samples contained goethite (L100–100) and rutile (Blank 100, East 1–60, L50–60, and L100–30) phases, showing the accumulation of Fe-and Ti-containing compounds, respectively. The presence of these minerals suggests that the soils of the area are at an advanced weathering stage. A mineralogical assay of clayey soils from hardsetting horizons of Brazilian soils revealed the occurrence of minerals containing Si, Al, Fe, and Ti due to advanced weathering (Giarola et al. 2009). Anorthite and albite that are endmembers of the feldspar group of minerals were common in many soil samples where the former mineral was enriched with Na making it sodic. This trend associated area soils with mafic igneous rock that has high weathering potential. The results agreed with a survey by Norman (2013) that reported the dominance of mafic rocks enriched with Si, Al, Ca, Mg, and Na in the area and the larger Eastern Cape Province.
Ground granulated blast furnace slag to control alkali induced swell in kaolinitic soils
Published in International Journal of Geotechnical Engineering, 2019
Sai Kumar Vindula, Rama Vara Prasad Chavali, P. Hari Prasad Reddy, T. Srinivas
XRD patterns of CC mixed with 10% GGBS inundated with 4N NaOH in comparison with CC inundated with water and 4N NaOH are shown in Figure 8. CC, which predominantly contains kaolinite along with calcite and ankerite, has shown more intense peaks pertaining to sodalite (6.33, 3.65 and 2.58 Å) upon interaction with 4N NaOH. These sodalite peaks are mainly due to dissolution of aluminasilicate nucleus of clay mineral (Chavali et al. 2017). Addition of 10% GGBS to the 4N NaOH CC, enhanced formations of gismondine (calcium alumina silicate hydrate-CASH) mineral. These CASH formations are the indicators of reaction between calcium predominant GGBS and silica and alumina from kaolinite. Peaks pertaining to gismondine (2.45 and 2.03 Å) are well identified in the XRD patterns.