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Polycarboxylates are
Polycarboxylates are used as
Polycarboxylates are organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
s with several carboxylic acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...
groups. Butane-1,2,3,4-tetracarboxylate is one example. Often, polycarboxylate refers to linear polymer
A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
s with a high molecular mass
The molecular mass () is the mass of a given molecule, often expressed in units of daltons (Da). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quan ...
(Mr ≤ 100 000) and with many carboxylate
In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge.
Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,... ...
groups. They are polymers of acrylic acid or copolymers
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are som ...
of acrylic acid
Acrylic acid (IUPAC: prop-2-enoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has ...
and maleic acid
Maleic acid or ''cis''-butenedioic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO2CCH=CHCO2H. Maleic acid is the ''cis'' Cis–trans isomerism, isomer of butenedioic acid, ...
. The polymer
A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
is used as the sodium salt
Sodium salts are salt (chemistry), salts composed of a sodium cation and any anion. The anion may be the conjugate base of some Inorganic compound, inorganic or organic acids, or any monatomic or polyatomic anion. They can be formed by the Neutra ...
(see: sodium polyacrylate
Sodium polyacrylate (ACR, ASAP, or PAAS), also known as waterlock, is a sodium salt of polyacrylic acid with the chemical formula ��CH2−CH(CO2Na)− and has broad applications in consumer products. This Superabsorbent polymer, super-absorb ...
).
Use
Polycarboxylates are used as builders
Builder may refer to:
Construction
* Construction worker, who specializes in building work
* Carpenter, a skilled craftsman who works with wood
* General contractor, that specializes in building work
** Subcontractor
* Real estate developer, who ...
in detergents. Their high chelating
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These l ...
power, even at low concentrations, lowers deposits
A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, current accounts or any of several other types of accounts explained below.
...
on the laundry and inhibits the growth of calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
crystals.
As applied to concrete, PCE-based superplasticizers can reduce water content by up to 40% at low dosages of around 0.12% to 0.22% without compromising fluidity. Polycarboxylate superplasticizers accelerate the early strength development of concrete and mortar. They also help with slump retention, ensuring concrete consistency and workability. With a higher slump rating, concrete can be more fluid and pumpable, especially for projects involving long-distance pumping and bulk construction.
Environmental considerations
Polycarboxylates are poorlybiodegradable
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...
but have a low ecotoxicity
Ecotoxicity, the subject of study in the field of ecotoxicology (a portmanteau of ecology and toxicology), refers to the biological, chemical or physical stressors that affect ecosystems. Such stressors can occur in the natural environment at de ...
. In the sewage treatment plant
Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water p ...
, the polymer remains largely in the sludge and is separated from the wastewater
Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...
.
Polyamino acids like polyaspartic acid and polyglutamic acid
Polyglutamic acid (PGA) is a polymer of the amino acid glutamic acid (GA). Depending on where the individual monomers connect, PGA can be gamma PGA (poly-γ-glutamic acid, γ-PGA), the form where the peptide bonds are between the amino group of G ...
have better biodegradability
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...
but lower chelating performance than polyacrylates. They are also less stable towards heat and alkali. Since they contain nitrogen, they can contribute to eutrophication
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...
.
See also
*tricarboxylic acid
A tricarboxylic acid is an organic carboxylic acid that contain three carboxyl functional groups (−COOH). A well-known example is citric acid.
Promient examples
Some prominent substituted tricarboxylic acids
Citric acid, is used in the c ...
s
References
{{reflist Polymers Salts and esters of carboxylic acids