Clarifying agent


Clarifying agent

Clarifying agents are used to remove suspended solids from liquids during flocculation.

Contents

Process

Particles finer than 0.1 µm (10-7m) in water remain continuously in motion due to electrostatic charge (often negative) which causes them to repel each other. Once their electrostatic charge is neutralized by the use of coagulant chemical, the finer particles start to collide and agglomerate (combine together) under the influence of Van der Waals's forces. These larger and heavier particles are called flocs.

Flocculants, or flocculating agents (also known as flocking agents), are chemicals that promote flocculation by causing colloids and other suspended particles in liquids to aggregate, forming a floc. Flocculants are used in water treatment processes to improve the sedimentation or filterability of small particles. For example, a flocculant may be used in swimming pool or drinking water filtration to aid removal of microscopic particles which would otherwise cause the water to be turbid (cloudy) and which would be difficult or impossible to remove by filtration alone.

Many flocculants are multivalent cations such as aluminium, iron, calcium or magnesium.[1] These positively charged molecules interact with negatively charged particles and molecules to reduce the barriers to aggregation. In addition, many of these chemicals, under appropriate pH and other conditions such as temperature and salinity, react with water to form insoluble hydroxides which, upon precipitating, link together to form long chains or meshes, physically trapping small particles into the larger floc.

Long-chain polymer flocculants, such as modified polyacrylamides, are manufactured and sold by the flocculant producing business. These can be supplied in dry or liquid form for use in the flocculation process. The most common liquid polyacrylamide is supplied as an emulsion with 10-40% actives and the rest is a carrier fluid, surfactants and latex. Emulsion polymers require activation to invert the emulsion and allow the electrolyte groups to be exposed.

Agents

The following natural products are used as flocculants:[2]

See also

References

  1. ^ Global Health and Education Foundation (2007). "Conventional Coagulation-Flocculation-Sedimentation". Safe Drinking Water is Essential. National Academy of Sciences. http://drinking-water.org/html/en/Treatment/Coagulation-Flocculation-technologies.html. Retrieved 2007-12-01. 
  2. ^ P. Somasundaran "Encyclopedia of surface and colloid science, Volume 7, pp 4980-4982."

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • clarifying agent — skaidriklis statusas T sritis chemija apibrėžtis Medžiaga, mažinanti sistemos drumstumą. atitikmenys: angl. clarificant; clarifying agent rus. осветлитель …   Chemijos terminų aiškinamasis žodynas

  • Beer — This article is about the alcoholic beverage. For other uses, see Beer (disambiguation). Schlenkerla Rauchbier straight from the cask …   Wikipedia

  • Brewing — Brewer redirects here. For other uses, see Brewer (disambiguation). This article is about the commercial brewing of beer. For making tea, see Steeping. For homebrewing, see Homebrewing. A 16th century brewery Brewing is the production of beer… …   Wikipedia

  • isinglass — SYN: ichthyocolla. [Old Ger. huysenblas, sturgeon s bladder] * * * isin·glass īz ən .glas, ī ziŋ n 1) a semitransparent whitish very pure gelatin prepared from the air bladders of fishes (as sturgeons) and used esp. as a clarifying agent and in… …   Medical dictionary

  • Liquid silicon dioxide — is commonly used as a clarifying agent in the production of wine or other fermented beverages. Commercial names for the substance include Kieselsol, Siligel and others. Often the liquid silicon dioxide is used in conjunction with gelatin to… …   Wikipedia

  • Tannic acid — IUPAC name 2,3 dihydroxy 5 ({[(2R,3R,4S,5R,6R) 3,4,5,6 tetrakis({3,4 dihydroxy 5 [(3,4,5 trihydroxyphenyl)carbonyloxy]phenyl}carbonylox …   Wikipedia

  • agar — /ah gahr, ag euhr/, n. 1. Also, agar agar. Also called Chinese gelatin, Chinese isinglass, Japanese gelatin, Japanese isinglass. a gelatinlike product of certain seaweeds, used for solidifying certain culture media, as a thickening agent for ice… …   Universalium

  • carrageenan — car·ra·geen·an or car·ra·geen·in .kar ə gē nən n a colloid extracted from various red algae and esp. Irish moss and used esp. as a suspending agent (as in foods) and as a clarifying agent (as for beverages) and in controlling crystal growth in… …   Medical dictionary

  • Agar — or agar agar is a gelatinous substance derived from seaweed. Historically and in a modern context, it is chiefly used as an ingredient in desserts throughout Japan, but in the past century has found extensive use as a solid substrate to contain… …   Wikipedia

  • Tannin — For other uses, see Tannin (demon). Tannic acid …   Wikipedia


We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.