A hydrophile, from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 (hydros) "water" and φιλια (philia) "love," is a molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 or other molecular entity
Molecular entity
According to the IUPAC Gold Book a molecular entity is "any constitutionally or isotopically distinct atom, molecule, ion, ion pair, radical, radical ion, complex, conformer, etc., identifiable as a separately distinguishable entity"....

 that is attracted to, and tends to be dissolved by water. A hydrophilic molecule or portion of a molecule is one that has a tendency to interact with or be dissolved by, water and other polar substances. This is thermodynamic
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...

ally favorable, and makes these molecules soluble not only in water, but also in other polar solvents. There are hydrophilic and hydrophobic parts of the cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...


A hydrophilic molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 or portion of a molecule is one that is typically charge-polarized and capable of hydrogen bond
Hydrogen bond
A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...

ing, enabling it to dissolve more readily in water than in oil or other hydrophobic solvents. Hydrophilic and hydrophobic molecules are also known as polar molecules and nonpolar molecules, respectively. Some hydrophilic substances do not dissolve. This type of mixture is called a colloid
A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...

. Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...

,,,which is amphipathic, has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both waters and oils.

An approximate rule of thumb for hydrophilicity of organic compounds is that solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...

 of a molecule in water is more than 1 mass % if there is at least one neutral hydrophile group per 5 carbons, or at least one electrically charged hydrophile group per 7 carbons.

Hydrophilic membrane filtration

Hydrophilic membrane filtration
Membrane technology
The membrane technology covers all process engineering measures for the transport of substances between two fractions with the help of permeable membranes...

is used in several industries to filter various liquids. These hydrophilic filters are used in the medical, industrial, and biochemical fields to filter such elements as bacteria, viruses, proteins, particulates, drugs, and other contaminates.

Unlike other membranes, hydrophilic membranes do not require pre-wetting. Hydrophilic membrane fabric can filter liquids and water in its dry state. Although most hydrophilic membranes are used in low heat filtration processes, many new hydrophilic membrane fabrics are used to filter hot liquids and fluids.
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