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Water Treatment Operations
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Oxidation filtration technologies may be effective in arsenic removal technologies. Research of oxidation filtration technologies has primarily focused on greensand filtration. As a result, the following discussion focuses on the effectiveness of greensand filtration as an arsenic removal technology. Substantial arsenic removal has been seen using greensand filtration (Subramanian et al., 1997). The active material in “greensand” is glauconite, a green, iron-rich, clay-like mineral that has ion exchange properties. Glauconite often occurs in nature as small pellets mixed with other sand particles, giving a green color to the sand. The glauconite sand is treated with KMnO4 until the sand grains are coated with a layer of manganese oxides, particularly manganese dioxide. The principle behind this arsenic removal treatment is multi-faceted and includes oxidation, ion exchange, and adsorption. Arsenic compounds displace species from the manganese oxide (presumably OH− and H2O), becoming bound to the greensand surface—in effect an exchange of ions. The oxidative nature of the manganese surface converts arsenite to arsenate and arsenate is adsorbed to the surface. As a result of the transfer of electrons and adsorption of arsenate, reduced manganese (Mn) is released from the surface.
Sedimentary rocks
Published in W.S. MacKenzie, A.E. Adams, K.H. Brodie, Rocks and Minerals in Thin Section, 2017
W.S. MacKenzie, A.E. Adams, K.H. Brodie
Glauconite is a potassium iron alumino-silicate which forms in shallow marine environments and is widespread in sandstones and limestones. Figure 148 and Figure 149 show a glauconitic sandstone cemented by calcite. The glauconite occurs as rounded aggregates of very small crystals with a characteristic green colour. This colour masks the interference colours. Quartz is rounded, clear in plane-polarized light (Figure 148) and showing shades of grey with crossed polars (Figure 149). The calcite cement with its high relief shows high-order interference colours.
Latest Miocene (Kapitean/Messinian) glauconite and the central Chatham Rise greensand: an enigmatic, highly condensed, relict/palimpsest deposit on the modern seafloor
Published in New Zealand Journal of Geology and Geophysics, 2022
Campbell S. Nelson, Anna S. Lawless, Scott D. Nodder, Horst Zwingmann
Glauconite, a product of seafloor authigenesis and typically found as distinctive green pelletal grains in many marine sedimentary deposits, is an iron and potassium-rich, hydrous aluminium phyllosilicate mineral with a general formula of (K,Na,Ca)(Fe,Al,Mg,Mn)2(Si,Al)4O10(OH)2 (Velde 2004; Banerjee et al. 2016). In terms of mineral structure, the name glauconite includes a wide spectrum of types (referred to as ‘glaucony’ by Odin and Létolle 1980) from smectitic glauconite, with a variable mix of expandable layers, to end-member non-expandable micaceous glauconite (McRae 1972; Thompson and Hower 1975; Odin and Matter 1981).
Studying glauconite of the bakchar deposit (Western Siberia) as a prospective sorbent for heavy metals
Published in Journal of Environmental Science and Health, Part A, 2020
Dmitrii Martemianov, Evgenii Plotnikov, Maxim Rudmin, Andrey Tyabayev, Anton Artamonov, Partha Kundu
The content of glauconite in the initial samples was 66% (Figure 2). The glauconite pellets (grains, granules) have isometric, rounded (globular) morphological forms (Figure 3a) with sizes 0.4–0.1 mm, greenish in color. The internal structure of the globules reveals randomly distributed plates and flakes with jagged contours (Figure 3b). This structure is an important feature that determines the high sorption properties of the mineral. Sometimes, aggregates of pyrite appear on glauconite grains (Figure 3c,d). A wide range of mineral micro inclusions in glauconites of the Bakchar deposit was described earlier,[38] which indicates a high sorption ability of the natural mineral. The detailed chemical composition of glauconitolite and glauconite concentrate is presented in Table 1. The content of K2O and Fe2O3 increases in glauconite concentrate relative to glauconitolite, while decreasing SiO2 and Al2O3. It is explained by removal of quartz and aluminosilicate rock cement during enrichment. The crystal-chemical formula for glauconite used in this study has the following averaged formula K0.54 (Fe1.19Mg0.27Ca0.03)1.49[Si3.38Al0.56O10](OH)2∗nH2O. This glauconite belongs to the evolved type according to Odin's classification[17,44] and unaltered within the deposit. The test samples contain oxide forms of iron and aluminum, which are effective sorbents themselves. In turn, glauconite concentrate contains less impurity elements and more Fe2O3, which is used for the production of sorbents. X-Ray diffractograms of natural and ethylene glycol-saturated glauconite preparations show five basal maxima, of which the reflections 001 and 003 are the most intense (Figure 4). Natural samples (Figure 4a) of glauconite show basal reflection (001) peaks at 10.8 Å, (020) reflections at 4.6 Å and (003) reflections at 3.4 Å. On samples impregnated with glycerin (001), the reflection is shifted from 10.8 to 9.6 Å, (020) – from 4.6 to 4.5 Å, and (003) reflections practically do not change (Figure 4b).