Using organic contaminant adsorption isotherms and sorptive behavior, organophilic-type organoclays (which produce simple, linear isotherms) are defined as having large exchanged organic-cation alkyl groups. These groups seem to act as a solvent phase (e.g. partitioning phase, i.e., solubilized), but are located in the interlayer, to absorb organic contaminants (Jaynes and Boyd, 1991b).

a) Synthetic systems. These clays are prepared from smectite or vermiculite by using large quaternary (> C-10) organic cations, such as hexadecyltrimethylammonium (C-16) or dioctadecyltrimethylammonium (C-18). These higher charge clay minerals (e.g., vermiculite, illite, high-charge smectite) adsorb greater numbers of large organic cations and yield organoclays that are more effective in absorbing organic contaminants compared to the unmodified clay. See also Boyd and Jaynes (1994).
b) Natural systems. Soil organic matter and organic compounds adsorbed to (internal or external) clay- mineral surfaces can act as a solvent phase for organic contaminants dissolved in water. Organic compounds (e.g., benzene, toluene, xylenes in gasoline) are more soluble in soil organic matter or the organic phase derived from organic compounds adsorbed to mineral particles than in water. Nonionic organic compounds may be partitioned (i.e. solubilized) into soil organic matter; see Chiou et al. (1979).
Cf., organoclay, adsorptive; organoclay

A characteristic property of a clay whereby the clay can sorb an organic solvent. These clays are usually surface modified, commonly by sorbing various quaternary ammonium compounds, which allow the clay to swell in organic liquids.
See organoclay.
Cf., organophobic

See organophilic, organoclay.

A characteristic property of a clay whereby the clay repels an organic liquid. Most naturally occurring clays are organophobic and are not wetted by nonpolar organic liquids.
See organoclay
Cf., organophilic

A trioctahedral member of the true mica group. The end-member, ideal formula is KLi₂Ti⁴⁺Si₄O₁₀(O,F), and orlovite occurs as the 1M polytype. Orlovite is from the Darai-Pioz alkaline massif of the Garmskii district, northern Tajikistan. Ti occurs in two positions in what is normally the M1 site in a mica (the M1 site is typically on a center of symmetry, but in orlovite each of the positions is displaced along the m plane away from the center) separated by 0.432 Å, indicating short range order where Ti is occupied in one domain in one of these positions and in the other domain by the other (Sokolova et al., 2018). Charge balance to offset the 4+ charge of the Ti cation occurs by the substitution of an oxygen anion for fluorine.

See reyerite group.

See alkali feldspar.

A pyroxene subgroup of Mg-Fe pyroxenes in the enstatite-ferrosilite solid-solution series with orthorhombic (Pbca, Pbcn) symmetry. See pyroxene group for additional details.
Cf., enstatite

See crystal system.

A physical process by which a solvent (typically, water) diffuses through a semi-permeable membrane (a porous material which is permeable to the solvent, but not the solute), owing to differences in solvent activity of two solutions which are separated by the membrane.