For graphs in which the concentration of adsorbate per unit adsorbent is on the y axis and pH is on the x axis (adsorption vs pH plot), an adsorption edge (sharp increase in adsorption at a specific pH) for an oxide or phyllosilicate surface occurs when the plotted curve shows an “S-shape”. An adsorption edge is commonly encountered for many cations adsorbed from a fluid onto the surface of a mineral or other solid substance (e.g., biological matter, glass).
Cf., adsorption envelope
For graphs in which the concentration of adsorbate per unit adsorbent is on the y axis and pH is on the x axis (adsorption vs pH plot), an adsorption envelope occurs if adsorbed concentration decreases with pH, which is commonly encountered for many anions adsorbed from a fluid on an oxide or phyllosilicate surface.
Cf., adsorption edge
A plot of the amount of a substance adsorbed per unit surface area (or in less rigorous terminology as per unit mass) of a solid or liquid as a function of the equilibrium concentration of the adsorbate, at a specific temperature and pressure.
The adsorption of anions on basal OH surfaces of a phase where structural hydroxyl groups are replaced by other anions, or on particle edges where unsatisfied positive bonds occur; exchange of edge hydroxyls also may occur (modified from O’Bannon, 1984).
The adsorption of cations on basal surfaces where negative charges occur, possibly as a result of isomorphous replacement within the structure, and/or adsorption on mineral surfaces where unsatisfied charges may occur often where there are incomplete coordination units. Surface adsorption is common on the basal oxygen atom plane of the 2:1 layer of phyllosilicates. Edge adsorption predominates in kaolin-type phyllosilicates having 1:1 layers (modified from O’Bannon, 1984).
Aesthetic medicine is a discipline involving all medical methods, including the application of materials such as some clays, to skin for cosmetic purposes (e.g., to tighten skin, add/change color, stimulate circulation, or reduce a scar ). Such procedures are generally non-invasive or minimally invasive. Procedures that are non-invasive or minimally invasive are typical.
Cf., active principle, antibacterial clay, geotherapy, healing clay, medicinal clay, pelotherapy
An obsolete, local term for a fibrous talc from New York State, USA; or for pyrophyllite from China (also obsolete).
An obsolete term for pyrophyllite or a mixture with dominant pyrophyllite.
Ageing refers to a) a process where the physical properties, for example the rheology, of wet clay are improved by allowing the clay to sit undisturbed for a period, sometimes for years but more often for days or months, to allow the water to become more homogeneously distributed or to promote the growth of microorganisms. An improvement in plasticity by ageing is important for pressing and drawing of the clay for commercial production of ceramics.
Syn., aging, maturation; b) in soil mechanics, aging is also referred to the process of secondary consolidation or drained creep.
Cf., drained creep, secondary compression