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Osmosis

From Wikipedia, in a visual modern way
For other uses, see Osmosis (disambiguation).
The process of osmosis over a semi-permeable membrane. The blue dots represent particles driving the osmotic gradient.
The process of osmosis over a semi-permeable membrane. The blue dots represent particles driving the osmotic gradient.

Osmosis (/ɒzˈmoʊsɪs/, US also /ɒs-/)[1] is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region of higher solute concentration),[2] in the direction that tends to equalize the solute concentrations on the two sides.[3][4][5] It may also be used to describe a physical process in which any solvent moves across a selectively permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations.[6][7] Osmosis can be made to do work.[8] Osmotic pressure is defined as the external pressure required to be applied so that there is no net movement of solvent across the membrane. Osmotic pressure is a colligative property, meaning that the osmotic pressure depends on the molar concentration of the solute but not on its identity.

Osmosis is a vital process in biological systems, as biological membranes are semipermeable. In general, these membranes are impermeable to large and polar molecules, such as ions, proteins, and polysaccharides, while being permeable to non-polar or hydrophobic molecules like lipids as well as to small molecules like oxygen, carbon dioxide, nitrogen, and nitric oxide. Permeability depends on solubility, charge, or chemistry, as well as solute size. Water molecules travel through the plasma membrane, tonoplast membrane (vacuole) or organelle membranes by diffusing across the phospholipid bilayer via aquaporins (small transmembrane proteins similar to those responsible for facilitated diffusion and ion channels). Osmosis provides the primary means by which water is transported into and out of cells. The turgor pressure of a cell is largely maintained by osmosis across the cell membrane between the cell interior and its relatively hypotonic environment.

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American English

American English

American English, sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. English is the most widely spoken language in the United States and in most circumstances is the de facto common language used in government, education and commerce. Since the 20th century, American English has become the most influential form of English worldwide.

Diffusion

Diffusion

Diffusion is the net movement of anything generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential. It is possible to diffuse "uphill" from a region of lower concentration to a region of higher concentration, like in spinodal decomposition. Diffusion is a stochastic process due to the inherent randomness of the diffusing entity and can be used to model many real-life stochastic scenarios. Therefore, diffusion and the corresponding mathematical models has applications in several fields, beyond physics, such as statistics, probability theory, information theory, neural networks, finance and marketing etc.

Solvent

Solvent

A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell.

Osmotic pressure

Osmotic pressure

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane.

Pressure

Pressure

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.

Colligative properties

Colligative properties

In chemistry, colligative properties are those properties of solutions that depend on the ratio of the number of solute particles to the number of solvent particles in a solution, and not on the nature of the chemical species present. The number ratio can be related to the various units for concentration of a solution such as molarity, molality, normality (chemistry), etc. The assumption that solution properties are independent of nature of solute particles is exact only for ideal solutions, which are solutions that exhibit thermodynamic properties analogous to those of an ideal gas, and is approximate for dilute real solutions. In other words, colligative properties are a set of solution properties that can be reasonably approximated by the assumption that the solution is ideal.

Molar concentration

Molar concentration

Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol/dm3 in SI unit. A solution with a concentration of 1 mol/L is said to be 1 molar, commonly designated as 1 M.

Biology

Biology

Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.

Biological membrane

Biological membrane

A biological membrane, biomembrane or cell membrane is a selectively permeable membrane that separates the interior of a cell from the external environment or creates intracellular compartments by serving as a boundary between one part of the cell and another. Biological membranes, in the form of eukaryotic cell membranes, consist of a phospholipid bilayer with embedded, integral and peripheral proteins used in communication and transportation of chemicals and ions. The bulk of lipids in a cell membrane provides a fluid matrix for proteins to rotate and laterally diffuse for physiological functioning. Proteins are adapted to high membrane fluidity environment of the lipid bilayer with the presence of an annular lipid shell, consisting of lipid molecules bound tightly to the surface of integral membrane proteins. The cell membranes are different from the isolating tissues formed by layers of cells, such as mucous membranes, basement membranes, and serous membranes.

Chemical polarity

Chemical polarity

In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end.

Aquaporin

Aquaporin

Aquaporins, also called water channels, are channel proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells. The cell membranes of a variety of different bacteria, fungi, animal and plant cells contain aquaporins through which water can flow more rapidly into and out of the cell than by diffusing through the phospholipid bilayer. Aquaporins have six membrane-spanning alpha helical domains with both carboxylic and amino terminals on the cytoplasmic side. Two hydrophobic loops contain conserved asparagine-proline-alanine which form a barrel surrounding a central pore-like region that contains additional protein density. Because aquaporins are usually always open and are prevalent in just about every cell type, this leads to a misconception that water readily passes through the cell membrane down its concentration gradient. Water can pass through the cell membrane through simple diffusion because it is a small molecule, and through osmosis, in cases where the concentration of water outside of the cell is greater than that of the inside. However, because water is a polar molecule this process of simple diffusion is relatively slow, and in tissues with high water permeability the majority of water passes through aquaporin.

Cell (biology)

Cell (biology)

The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites. The term comes from the Latin word cellula meaning 'small room'.

History

The "endosmometer" invented by Dutrochet
The "endosmometer" invented by Dutrochet

Some kinds of osmotic flow have been observed since ancient times, e.g., on the construction of Egyptian pyramids.[9] Jean-Antoine Nollet first documented observation of osmosis in 1748.[10] The word "osmosis" descends from the words "endosmose" and "exosmose", which were coined by French physician René Joachim Henri Dutrochet (1776–1847) from the Greek words ἔνδον (éndon "within"), ἔξω (éxō "outer, external"), and ὠσμός (ōsmós "push, impulsion").[11] In 1867, Moritz Traube invented highly selective precipitation membranes, advancing the art and technique of measurement of osmotic flow.[9]

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Osmometer

Osmometer

An osmometer is a device for measuring the osmotic strength of a solution, colloid, or compound.

Jean-Antoine Nollet

Jean-Antoine Nollet

Jean-Antoine Nollet was a French clergyman and physicist who did a number of experiments with electricity and discovered osmosis. As a deacon in the Catholic Church, he was also known as Abbé Nollet.

Henri Dutrochet

Henri Dutrochet

René Joachim Henri Dutrochet was a French physician, botanist and physiologist. He is best known for his investigation into osmosis.

Moritz Traube

Moritz Traube

Moritz Traube was a German chemist and universal private scholar.

Description

Osmosis is the movement of a solvent across a semipermeable membrane toward a higher concentration of solute. In biological systems, the solvent is typically water, but osmosis can occur in other liquids, supercritical liquids, and even gases.[12][13]

When a cell is submerged in water, the water molecules pass through the cell membrane from an area of low solute concentration to high solute concentration. For example, if the cell is submerged in saltwater, water molecules move out of the cell. If a cell is submerged in freshwater, water molecules move into the cell.

Water passing through a semi-permeable membrane
Water passing through a semi-permeable membrane

When the membrane has a volume of pure water on both sides, water molecules pass in and out in each direction at exactly the same rate. There is no net flow of water through the membrane.

Osmosis can be demonstrated when potato slices are added to a high salt solution. The water from inside the potato moves out to the solution, causing the potato to shrink and to lose its 'turgor pressure'. The more concentrated the salt solution, the bigger the loss in size and weight of the potato slice.

Chemical gardens demonstrate the effect of osmosis in inorganic chemistry.

Mechanism

The mechanism responsible for driving osmosis has commonly been represented in biology and chemistry texts as either the dilution of water by solute (resulting in lower concentration of water on the higher solute concentration side of the membrane and therefore a diffusion of water along a concentration gradient) or by a solute's attraction to water (resulting in less free water on the higher solute concentration side of the membrane and therefore net movement of water toward the solute). Both of these notions have been conclusively refuted.

The diffusion model of osmosis is rendered untenable by the fact that osmosis can drive water across a membrane toward a higher concentration of water.[14] The "bound water" model is refuted by the fact that osmosis is independent of the size of the solute molecules—a colligative property[15]—or how hydrophilic they are.

It is difficult to describe osmosis without a mechanical or thermodynamic explanation, but essentially there is an interaction between the solute and water that counteracts the pressure that otherwise free solute molecules would exert. One fact to take note of is that heat from the surroundings is able to be converted into mechanical energy (water rising).

Many thermodynamic explanations go into the concept of chemical potential and how the function of the water on the solution side differs from that of pure water due to the higher pressure and the presence of the solute counteracting such that the chemical potential remains unchanged. The virial theorem demonstrates that attraction between the molecules (water and solute) reduces the pressure, and thus the pressure exerted by water molecules on each other in solution is less than in pure water, allowing pure water to "force" the solution until the pressure reaches equilibrium.[15]

Role in living things

Effect of different solutions on blood cellsMicrographs of osmotic pressure on red blood cells (RBC)Plant cell in different environments.
Effect of different solutions on blood cells
Effect of different solutions on blood cellsMicrographs of osmotic pressure on red blood cells (RBC)Plant cell in different environments.
Micrographs of osmotic pressure on red blood cells (RBC)
Effect of different solutions on blood cellsMicrographs of osmotic pressure on red blood cells (RBC)Plant cell in different environments.
Plant cell in different environments.

Osmotic pressure is the main agent of support in many plants. The osmotic entry of water raises the turgor pressure exerted against the cell wall, until it equals the osmotic pressure, creating a steady state.

When a plant cell is placed in a solution that is hypertonic relative to the cytoplasm, water moves out of the cell and the cell shrinks. In doing so, the cell becomes flaccid. In extreme cases, the cell becomes plasmolyzed – the cell membrane disengages with the cell wall due to lack of water pressure on it.

When a plant cell is placed in a solution that is hypotonic relative to the cytoplasm, water moves into the cell and the cell swells to become turgid.

Osmosis is responsible for the ability of plant roots to draw water from the soil. Plants concentrate solutes in their root cells by active transport, and water enters the roots by osmosis. Osmosis is also responsible for controlling the movement of guard cells.

In unusual environments, osmosis can be very harmful to organisms. For example, freshwater and saltwater aquarium fish placed in water of a different salinity than that to which they are adapted to will die quickly, and in the case of saltwater fish, dramatically. Another example of a harmful osmotic effect is the use of table salt to kill leeches and slugs.

Suppose an animal or a plant cell is placed in a solution of sugar or salt in water.

  • If the medium is hypotonic relative to the cell cytoplasm, the cell will gain water through osmosis.
  • If the medium is isotonic, there will be no net movement of water across the cell membrane.
  • If the medium is hypertonic relative to the cell cytoplasm, the cell will lose water by osmosis.

This means that if a cell is put in a solution which has a solute concentration higher than its own, it will shrivel, and if it is put in a solution with a lower solute concentration than its own, the cell will swell and may even burst.

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Osmotic pressure

Osmotic pressure

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane.

Cell wall

Cell wall

A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes. A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.

Steady state (biochemistry)

Steady state (biochemistry)

In biochemistry, steady state refers to the maintenance of constant internal concentrations of molecules and ions in the cells and organs of living systems. Living organisms remain at a dynamic steady state where their internal composition at both cellular and gross levels are relatively constant, but different from equilibrium concentrations. A continuous flux of mass and energy results in the constant synthesis and breakdown of molecules via chemical reactions of biochemical pathways. Essentially, steady state can be thought of as homeostasis at a cellular level.

Plasmolysis

Plasmolysis

Plasmolysis is the process in which cells lose water in a hypertonic solution. The reverse process, deplasmolysis or cytolysis, can occur if the cell is in a hypotonic solution resulting in a lower external osmotic pressure and a net flow of water into the cell. Through observation of plasmolysis and deplasmolysis, it is possible to determine the tonicity of the cell's environment as well as the rate solute molecules cross the cellular membrane.

Cell membrane

Cell membrane

The cell membrane is a biological membrane that separates and protects the interior of all cells from the outside environment. The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of cells and organelles, being selectively permeable to ions and organic molecules. In addition, cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity, and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall and the carbohydrate layer called the glycocalyx, as well as the intracellular network of protein fibers called the cytoskeleton. In the field of synthetic biology, cell membranes can be artificially reassembled.

Active transport

Active transport

In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient.

Guard cell

Guard cell

Guard cells are specialized plant cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore. The stomatal pores are largest when water is freely available and the guard cells turgid, and closed when water availability is critically low and the guard cells become flaccid. Photosynthesis depends on the diffusion of carbon dioxide (CO2) from the air through the stomata into the mesophyll tissues. Oxygen (O2), produced as a byproduct of photosynthesis, exits the plant via the stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Plants must balance the amount of CO2 absorbed from the air with the water loss through the stomatal pores, and this is achieved by both active and passive control of guard cell turgor pressure and stomatal pore size.

Leech

Leech

Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and in having ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid, and the coelom, the spacious body cavity found in other annelids, is reduced to small channels.

Slug

Slug

Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semislugs.

Factors

Osmotic pressure

Main article: Osmotic pressure

Osmosis may be opposed by increasing the pressure in the region of high solute concentration with respect to that in the low solute concentration region. The force per unit area, or pressure, required to prevent the passage of water (or any other high-liquidity solution) through a selectively permeable membrane and into a solution of greater concentration is equivalent to the osmotic pressure of the solution, or turgor. Osmotic pressure is a colligative property, meaning that the property depends on the concentration of the solute, but not on its content or chemical identity.

Osmotic gradient

The osmotic gradient is the difference in concentration between two solutions on either side of a semipermeable membrane, and is used to tell the difference in percentages of the concentration of a specific particle dissolved in a solution.

Usually the osmotic gradient is used while comparing solutions that have a semipermeable membrane between them allowing water to diffuse between the two solutions, toward the hypertonic solution (the solution with the higher concentration). Eventually, the force of the column of water on the hypertonic side of the semipermeable membrane will equal the force of diffusion on the hypotonic (the side with a lesser concentration) side, creating equilibrium. When equilibrium is reached, water continues to flow, but it flows both ways in equal amounts as well as force, therefore stabilizing the solution.

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Osmotic pressure

Osmotic pressure

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane.

Force

Force

In physics, a force is an influence that causes the motion of an object with mass to change its velocity, i.e., to accelerate. It can be a push or a pull, always with magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N) and represented by the symbol F.

Water

Water

Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless, and nearly colorless chemical substance, and it is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure.

Liquidity

Liquidity

Liquidity is a concept in economics involving the convertibility of assets and obligations. It can include:Market liquidity, the ease with which an asset can be sold Accounting liquidity, the ability to meet cash obligations when due Liquid capital, the amount of money that a firm holds Liquidity risk, the risk that an asset will have impaired market liquidity

Solution (chemistry)

Solution (chemistry)

In chemistry, a solution is a special type of homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. If the attractive forces between the solvent and solute particles are greater than the attractive forces holding the solute particles together, the solvent particles pull the solute particles apart and surround them. These surrounded solute particles then move away from the solid solute and out into the solution. The mixing process of a solution happens at a scale where the effects of chemical polarity are involved, resulting in interactions that are specific to solvation. The solution usually has the state of the solvent when the solvent is the larger fraction of the mixture, as is commonly the case. One important parameter of a solution is the concentration, which is a measure of the amount of solute in a given amount of solution or solvent. The term "aqueous solution" is used when one of the solvents is water.

Colligative properties

Colligative properties

In chemistry, colligative properties are those properties of solutions that depend on the ratio of the number of solute particles to the number of solvent particles in a solution, and not on the nature of the chemical species present. The number ratio can be related to the various units for concentration of a solution such as molarity, molality, normality (chemistry), etc. The assumption that solution properties are independent of nature of solute particles is exact only for ideal solutions, which are solutions that exhibit thermodynamic properties analogous to those of an ideal gas, and is approximate for dilute real solutions. In other words, colligative properties are a set of solution properties that can be reasonably approximated by the assumption that the solution is ideal.

Semipermeable membrane

Semipermeable membrane

Semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by osmosis. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry. How the membrane is constructed to be selective in its permeability will determine the rate and the permeability. Many natural and synthetic materials which are rather thick are also semipermeable. One example of this is the thin film on the inside of the egg.

Variation

Reverse osmosis

Main article: Reverse osmosis

Reverse osmosis is a separation process that uses pressure to force a solvent through a semi-permeable membrane that retains the solute on one side and allows the pure solvent to pass to the other side, forcing it from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.

Forward osmosis

Main article: Forward osmosis

Osmosis may be used directly to achieve separation of water from a solution containing unwanted solutes. A "draw" solution of higher osmotic pressure than the feed solution is used to induce a net flow of water through a semi-permeable membrane, such that the feed solution becomes concentrated as the draw solution becomes dilute. The diluted draw solution may then be used directly (as with an ingestible solute like glucose), or sent to a secondary separation process for the removal of the draw solute. This secondary separation can be more efficient than a reverse osmosis process would be alone, depending on the draw solute used and the feedwater treated. Forward osmosis is an area of ongoing research, focusing on applications in desalination, water purification, water treatment, food processing, and other areas of study.

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Reverse osmosis

Reverse osmosis

Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property that is driven by chemical potential differences of the solvent, a thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be "selective", this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as solvent molecules, e.g., water, H2O) to pass freely.

Osmotic pressure

Osmotic pressure

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane.

Forward osmosis

Forward osmosis

Forward osmosis (FO) is an osmotic process that, like reverse osmosis (RO), uses a semi-permeable membrane to effect separation of water from dissolved solutes. The driving force for this separation is an osmotic pressure gradient, such that a "draw" solution of high concentration, is used to induce a net flow of water through the membrane into the draw solution, thus effectively separating the feed water from its solutes. In contrast, the reverse osmosis process uses hydraulic pressure as the driving force for separation, which serves to counteract the osmotic pressure gradient that would otherwise favor water flux from the permeate to the feed. Hence significantly more energy is required for reverse osmosis compared to forward osmosis.

Desalination

Desalination

Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture. Saltwater is desalinated to produce water suitable for human consumption or irrigation. The by-product of the desalination process is brine. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on cost-effective provision of fresh water for human use. Along with recycled wastewater, it is one of the few rainfall-independent water resources.

Water purification

Water purification

Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption, but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.

Water treatment

Water treatment

Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.

Food processing

Food processing

Food processing is the transformation of agricultural products into food, or of one form of food into other forms. Food processing includes many forms of processing foods, from grinding grain to make raw flour to home cooking to complex industrial methods used to make convenience foods. Some food processing methods play important roles in reducing food waste and improving food preservation, thus reducing the total environmental impact of agriculture and improving food security.

Source: "Osmosis", Wikipedia, Wikimedia Foundation, (2022, November 28th), https://en.wikipedia.org/wiki/Osmosis.

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Further Reading

Osmotic pressure

Plasmolysis

Semipermeable membrane

Passive transport

Dialysis (chemistry)

Forward osmosis

Contractile vacuole

Tonicity

Osmotic concentration

Osmotic shock

History of cell membrane theory
See also
References
  1. ^ Jones, Daniel (2011). Roach, Peter; Setter, Jane; Esling, John (eds.). Cambridge English Pronouncing Dictionary (18th ed.). Cambridge University Press. ISBN 978-0-521-15255-6.
  2. ^ "Osmosis | A Level Notes".{{cite web}}: CS1 maint: url-status (link)
  3. ^ "Osmosis". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  4. ^ Osmosis, Encyclopædia Britannica on-line
  5. ^ Haynie, Donald T. (2001). Biological Thermodynamics. Cambridge: Cambridge University Press. pp. 130–136. ISBN 978-0-521-79549-4.
  6. ^ Waugh, A.; Grant, A. (2007). Anatomy and Physiology in Health and Illness. Edinburgh: Elsevier. pp. 25–26. ISBN 978-0-443-10101-4.
  7. ^ Osmosis Archived 22 February 2008 at the Wayback Machine. University of Hamburg. last change: 31 July 2003
  8. ^ "Statkraft to build the world's first prototype osmotic power plant". Statkraft. 3 October 2007. Archived from the original on 27 February 2009.
  9. ^ a b Hammel, H.T.; Scholander, P.F. (1976). Perspectives on the Mechanism of Osmosis and Imbibition In: Osmosis and tensile solvent. Springer-Verlag, Berlin, Heidelberg, New York. link.
  10. ^ L’Abbé Nollet (June 1748) "Recherches sur les causes du bouillonnement des liquides" (Researches on the causes of the boiling of liquids) Mémoires de Mathématique et de Physique, tirés des registres de l’Académie Royale des Sciences de l’année 1748, pp. 57–104; especially pp. 101–103. The Mémoires (1748) were printed in: Histoire de l’Académie Royale des Sciences Année 1748, which was published in 1752 and which contains a condensed version of Nollet's article on pages 10–19.

    Original text : Avant que de finir ce Mémoire, je crois devoir rendre compte d'un fait que je dois au hasard, & qui me parut d'abord … singulier … j'en avois rempli une fiole cylindrique, longue de cinq pouces, & d'un pouce de diamètre ou environ ; & l'ayant couverte d'un morceau de vessie mouillée & ficelée au col du vaisseau, je l'avois plongée dans un grand vase plein d'eau, afin d'être sûr qu'il ne rentrât aucun air dans l'esprit de vin. Au bout de cinq ou six heures, je fus tout surpris de voir que la fiole étoit plus pleine qu'au moment de son immersion, quoiqu'elle le fût alors autant que ses bords pouvoient le permettre ; la vessie qui lui servoit de bouchon, étoit devenue convexe & si tendue, qu’en la piquant avec une épingle, il en sortit un jet de liqueur qui s'éleva à plus d'un pied de hauteur.

    Translation : Before finishing this memoir, I think I should report an event that I owe to chance and which at first seemed to me … strange … I filled [with alcohol] a cylindrical vial, five inches long and about one inch in diameter; and [after] having covered it with piece of damp bladder [which was] tied to the neck of the vial, I immersed it in a large bowl full of water, in order to be sure that no air re-entered the alcohol. At the end of 5 or 6 hours, I was very surprised to see that the vial was fuller than at the moment of its immersion, although it [had been filled] as far as its sides would allow ; the bladder that served as its cap, bulged and had become so stretched that on pricking it with a needle, there came from it a jet of alcohol that rose more than a foot high.
  11. ^ Etymology of "osmosis" :
    • Henri Dutrochet, L'Agent Immédiat du Movement Vital Dévoilé dans sa Nature et dans son Mode d'Action chez les Végétaux et chez les Animaux [The immediate agent of living movement, its nature and mode of action revealed in plants and animals] (Paris, France: Dentu, 1826), pp. 115 and 126.
    • The intermediate word "osmose" and the word "osmotic" were coined by Scottish chemist Thomas Graham. See: Thomas Graham (1854) "VII. The Bakerian Lecture – On Osmotic Force," Philosophical Transactions of the Royal Society (London), vol. 144, pp. 177–288; see especially pp. 177, 178, and 227. See also: Thomas Graham and Henry Watts, Elements of Chemistry: Including the Applications of the Sciences in the Arts, 2nd ed. (London, England: Hippolyte Bailliere, 1858), vol. 2, p. 616.
    • The word "osmosis" first appeared in: Jabez Hogg, The Microscope: Its History, Construction, and Application..., 6th ed. (London, England: George Routledge and Sons, 1867), p. 226.
    • The etymology of the word "osmosis" is discussed in: Homer W. Smith (1960). "I. Theory of Solutions: A knowledge of the laws of solutions". Circulation. 21 (5): 808–817 (810). doi:10.1161/01.CIR.21.5.808. PMID 13831991.
  12. ^ Kramer, Eric; David Myers (2013). "Osmosis is not driven by water dilution". Trends in Plant Science. 18 (4): 195–197. doi:10.1016/j.tplants.2012.12.001. PMID 23298880.
  13. ^ Kramer, Eric; David Myers (2012). "Five popular misconceptions of osmosis". American Journal of Physics. 80 (694): 694–699. Bibcode:2012AmJPh..80..694K. doi:10.1119/1.4722325.
  14. ^ Kosinski, R. J.; C. K. Morlok (2008). "Challenging misconceptions about osmosis". Association for Biology Laboratory Education. 30: 63–87.
  15. ^ a b Borg, Frank (2003). "What is osmosis? Explanation and understanding of a physical phenomenon". arXiv:physics/0305011.
External links
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