Adobe

Durable, sun-dried, hardened bricks made from mixtures of water, clay, silt, sand and straw, or other fibrous organic materials

Adsorbate

Any substance which, in molecular, atomic, or ionic form, will penetrate into and be retained by another (liquid, solid, gel, etc.) material.
Cf., Solid-state diffusion, adsorbent

Adsorbed water

H2O molecules attracted to and adhered to by atomic forces at internal or external surfaces of a phyllosilicate or other material in thicknesses of one or more molecules. The term “water” (rather than “H2O”) is not precisely used here because “water” is a (liquid) phase.

Adsorption

The process of attraction and adherence of atoms, ions, or molecules from a (gas, liquid, etc.) solution to a surface.

Adsorption edge, surface characterization

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

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

Adsorption isotherm

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.

Adsorption, anion

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).

Adsorption, cation

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).