Ceramic Materials
The isoelectric points (IEP) of metal oxide ceramics are used extensively in material science in various aqueous processing steps (synthesis, modification, etc.). In the absence of chemisorbed or physisorbed species particle surfaces in aqueous suspension are generally assumed to be covered with surface hydroxyl species, M-OH (where M is a metal such as Al, Si, etc.). At pH values above the IEP, the predominate surface species is M-O-, while at pH values below the IEP, M-OH2+ species predominate. Some approximate values of common ceramics are listed below (Haruta and Brunelle, except where noted). The exact value can vary widely, depending on material factors such as purity and phase as well as physical parameters such as temperature. In addition, precise measurement of isoelectric points is difficult and requires careful techniques, even with modern methods. Thus, many sources often cite differing values for isoelectric points of these materials.
Read more about this topic: Isoelectric Point
Famous quotes containing the words ceramic and/or materials:
“He had first discovered a propensity for savagery in the acrid lavatories of a minor English public school where he used to press the heads of the new boys into the ceramic bowl and pull the flush upon them to drown their gurgling protests.”
—Angela Carter (1940–1992)
“In how few words, for instance, the Greeks would have told the story of Abelard and Heloise, making but a sentence of our classical dictionary.... We moderns, on the other hand, collect only the raw materials of biography and history, “memoirs to serve for a history,” which is but materials to serve for a mythology.”
—Henry David Thoreau (1817–1862)