Encyclopedia of Geochemistry

Living Edition
| Editors: William M. White

Colloids

  • Jean-François BoilyEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-39193-9_91-1

Definition

Colloids are (in)organic (poly)molecular particles in which at least one dimension is of the order ~1–1000 nm in length. They may occur as individually dispersed and/or aggregated particles of a given substance suspended in another substance. They cannot be separated by conventional forms of filtration or centrifugation.

Introduction

Colloidal suspensions consist of particles of one phase (solid, liquid, gas) in a second continuous phase. Particles are ~1–1000 nm (or even ~10 μm) wide in at least one direction, can be amorphous or crystalline, and be composed of inorganic, organic, or biological materials. Colloids of interest to Earth Sciences can be dispersed in solids, liquids, and gases, with representative examples shown in Table 1. Notable examples of colloids of biogeochemical importance include clays, fine silt, condensed Al(III) and Fe(III) (oxyhydr)oxides, as well as humic substances. Biocolloids are of organic nature and can include bacteria, viruses, protozoae,...
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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Department of ChemistryUmeå UniversityUmeåSweden