Content deleted Content added
Reverted 2 edits by Thesunnypurohit (talk): Spam |
m →Further reading: clean up spacing around commas and other punctuation fixes, replaced: , → , (2) |
||
| (32 intermediate revisions by 22 users not shown) | |||
Line 1:
{{Short description|Organic polymer matrix bearing ion-exchange functional groups}}
[[Image:Ion exchange resin beads.jpg|thumb|right|225px|Ion-exchange resin beads]]
An '''ion-exchange resin''' or '''ion-exchange polymer''' is a [[resin]] or [[polymer]] that acts as a medium for [[ion exchange]]. It is an [[solubility|insoluble]] matrix (or support structure) normally in the form of small (0.25–1.43 mm radius) [[microbead]]s, usually white or yellowish, fabricated from an [[organic chemistry|organic]] [[polymer]] substrate. The beads are typically [[porosity|porous]] (with a specific size distribution that will affect its properties), providing a large [[surface area]] on and inside them where the trapping of [[ion]]s occurs along with the accompanying release of other ions, and thus the process is called ion exchange. There are multiple types of ion-exchange resin, that differ in composition if the target is an anion or a cation. Most commercial resins are made of [[polystyrene sulfonate]]
[[Image:Orange resin.JPG|thumb|right|Ion-exchange resin beads]]
Ion-exchange resins are widely used in different [[separation process|separation]], purification, and decontamination processes. The most common examples are [[water softening]] and [[water purification]]. In many cases, ion-exchange resins were introduced in such processes as a more flexible alternative to the use of natural or artificial [[zeolite]]s. Also, ion-exchange resins are highly effective in the biodiesel filtration process.
==Types of resins==
Line 12:
Four main types of ion-exchange resins differ in their [[functional group]]s:
* strongly acidic cation (SAC), typically featuring [[sulfonic acid]] groups, e.g. [[sodium polystyrene sulfonate]] or [[polyAMPS]], often used for water softening and demineralization operations.
* strongly basic anion (SBA), typically featuring quaternary [[amino]] groups, for example, [[quaternary ammonium|trimethylammonium]] groups, e.g. [[polyAPTAC]]), good for silica, uranium, nitrates removal.
* weakly acidic cation (WAC), typically featuring [[carboxylic acid]] groups
* weakly basic anion (WBA), typically featuring primary, secondary, and/or tertiary [[amino]] groups, e.g. [[polyethylene amine]]. Are effective for demineralization where removal of SiO2 and CO2 are not required. Also effective for acid absorption.
Specialised ion-exchange resins are also known such as [[chelating resins]] ([[iminodiacetic acid]], [[thiourea]]-based resins, and many others).
Line 21:
Anion resins and cation resins are the two most common resins used in the ion-exchange process. While anion resins attract negatively charged ions, cation resins attract positively charged ions.
===Anion-exchange resins===
Formula: R-OH basic
Anion resins may be either strongly or weakly basic. Strongly basic anion resins maintain their negative charge across a wide pH range, whereas weakly basic anion resins are neutralized at higher pH levels.<ref name="Chromatography">[[Wikibooks:Proteomics/Protein Separations - Chromatography/Ion exchange#Anion Exchangers]].</ref> Weakly basic resins do not maintain their charge at a high pH because they undergo deprotonation.<ref name=Chromatography /> They do, however, offer excellent mechanical and chemical stability. This, combined with a high rate of ion exchange, make weakly base anion resins well suited for the organic salts.
Line 33 ⟶ 35:
Reaction:
:R−H + M<sup>+</sup> = R−M + H<sup>+</sup>.
Similar to anion resins, in cation resins the regeneration involves the use of a strongly acidic solution, e.g. aqueous hydrochloric acid. During regeneration, the regenerant chemical passes through the resin and flushes out the trapped positive ions, renewing the resin exchange capacity.
====Anion-exchange resin====
Line 44 ⟶ 48:
[[Anion-exchange chromatography]] makes use of this principle to extract and purify materials from [[mixture]]s or [[Solution (chemistry)|solution]]s.
== Characteristics ==
Ion exchange resins are often described according to some of the following features.<ref name=":1">{{Cite journal |last=Perry |first=John H. |date=September 1950 |title=Chemical engineers' handbook |journal=Journal of Chemical Education |volume=27 |issue=9 |page=533 |doi=10.1021/ed027p533.1 |bibcode=1950JChEd..27..533P |issn=0021-9584}}</ref>
* '''Capacity''': Represents the amount of ions that can be exchanged/stored per unit of mass of the resin. Typically is expressed in miligrams of ion per gram of resin (mg/g).
* '''[[Swelling capacity|Swelling]]''': Into contact with solvent, resins can swell (increase in volume). The swelling behavior of a resin is influenced by its chemical composition, polymer structure, and cross-linking. Resins with a higher degree of cross-linking tend to exhibit lower swelling tendencies compared to those with lower cross-linking. Swelling is typically expressed as the percentage increase in volume or weight of the resin when exposed to a specific solvent.
* '''[[Selectivity factor|Selectivity]]''': Refers to the resin's preference or ability to selectively adsorb or exchange certain ions over others. It is a fundamental property that determines the resin's effectiveness in separating or removing specific ions from a solution.
* '''Stability''': The integrity of the resin can be described in terms of mechanical and chemical resilience of the beads.
== Pores ==
The pore media of the resin particles is one of the most important parameters for the efficiency of the product. These pores make different functions depending on Their sizes and are the main feature responsible for the mass transfer between phases making the whole ion exchange process possible. There are three main types of pore sizes:<ref name=":1" />
* '''[[Microporous material|Micropore]]''': With a Slit width less than 2 nm, they are usually found at the end of larger pores and their main characteristic is to have superimposed wall potentials. This means, the particles inside them feel attracted towards their solid walls so they make contact with the active sites.
* '''[[Mesoporous material|Mesopore]]''': With a Slit width between 2 and 50 nm these mid-size pores have the main objective to withhold [[capillary condensation]] and is usually found before the micropores.
* '''[[Macropore]]''': With a Slit width bigger than 50 nm, these are the biggest size pores with the main purpose of being the main path for the molecules to enter the particle and later on redistribute through the other smaller channels
==Uses==
Line 55 ⟶ 73:
===Water purification===
{{main|Purified water}}
In this application, ion-exchange resins are used to remove [[poison]]ous (e.g. [[copper]]) and hazardous metal (e.g. [[lead]] or [[cadmium]]) ions from solution, replacing them with more innocuous ions, such as [[sodium]] and [[potassium]], in the process cation and anion exchange resins are used to remove dissolved ions from the water.
Few ion-exchange resins remove [[chlorine]] or organic contaminants from water – this is usually done by using an [[activated charcoal]] filter mixed in with the resin. There are some ion-exchange resins that do remove organic ions, such as MIEX (magnetic ion-exchange) resins. Domestic water purification resin is not usually recharged – the resin is discarded when it can no longer be used.
Line 72 ⟶ 90:
===Catalysis===
Ion exchange resins are used in [[organic synthesis]], e.g. for [[esterification]] and [[hydrolysis]]. Being high surface area and insoluble, they are suitable for vapor-phase and liquid-phase reactions. Examples can be found where basic (OH<sup>−</sup>-form) of ion exchange resins are used to neutralize of ammonium salts<ref>{{cite journal|title=ε-Aminocaproic Acid|
===Juice purification===
Line 86 ⟶ 104:
Ion-exchange resins are also used as [[excipient]]s in pharmaceutical formulations such as tablets, capsules, gums, and suspensions. In these uses the ion-exchange resin can have several different functions, including taste-masking, extended release, tablet disintegration, increased [[bioavailability]], and improving the chemical stability of the [[active ingredient]]s.
Selective [[chelating resin|polymeric chelators]] have been proposed for [[maintenance therapy]] of some pathologies, where chronic ion [[Bioaccumulation|accumulation]] occurs, such as [[Wilson disease]] (where [[copper]] accumulation occurs)<ref name="MattováPoučková2014">{{cite journal |last1=Mattová |first1=Jana |last2=Poučková |first2=Pavla |last3=Kučka |first3=Jan |last4=Škodová |first4=Michaela |last5=Vetrík |first5=Miroslav |last6=Štěpánek |first6=Petr |last7=Urbánek |first7=Petr |last8=Petřík |first8=Miloš|last9=Nový|first9=Zbyněk|last10=Hrubý|first10=Martin|title=Chelating polymeric beads as potential therapeutics for Wilson's disease|journal=European Journal of Pharmaceutical Sciences|volume=62|year=2014|pages=1–7|issn=0928-0987|doi=10.1016/j.ejps.2014.05.002|pmid=24815561 }}</ref> or [[hereditary hemochromatosis]] ([[iron overload]], where [[iron]] accumulation occurs)<ref name="Polomoscanik2005">{{cite journal|last1=Polomoscanik|first1=Steven C.|last2=Cannon|first2=C. Pat|last3=Neenan|first3=Thomas X.|last4=Holmes-Farley|first4=S. Randall|last5=Mandeville|first5=W. Harry|last6=Dhal|first6=Pradeep K.|title=Hydroxamic Acid-Containing Hydrogels for Nonabsorbed Iron Chelation Therapy: Synthesis, Characterization, and Biological Evaluation|journal=Biomacromolecules|volume=6|issue=6|year=2005|pages=2946–2953|issn=1525-7797|doi=10.1021/bm050036p|pmid=16283713}}</ref><ref name="QianSullivan2017">{{cite journal|last1=Qian|first1=Jian|last2=Sullivan|first2=Bradley P.|last3=Peterson|first3=Samuel J.|last4=Berkland|first4=Cory|title=Nonabsorbable Iron Binding Polymers Prevent Dietary Iron Absorption for the Treatment of Iron Overload|journal=ACS Macro Letters|volume=6|issue=4|year=2017|pages=350–353|issn=2161-1653|doi=10.1021/acsmacrolett.6b00945|pmid=35610854 }}</ref><ref name="Groborz2020">{{cite journal|last1=Groborz|first1=Ondřej|last2=Poláková|first2=Lenka|last3=Kolouchová|first3=Kristýna|last4=Švec|first4=Pavel|last5=Loukotová|first5=Lenka|last6=Miriyala|first6=Vijay Madhav|last7=Francová|first7=Pavla|last8=Kučka|first8=Jan|last9=Krijt|first9=Jan|last10=Páral|first10=Petr|last11=Báječný|first11=Martin|last12=Heizer|first12=Tomáš|last13=Pohl|first13=Radek|last14=Dunlop|first14=David|last15=Czernek|first15=Jiří|last16=Šefc|first16=Luděk|last17=Beneš|first17=Jiří|last18=Štěpánek|first18=Petr|last19=Hobza|first19=Pavel|last20=Hrubý|first20=Martin|title=Chelating Polymers for Hereditary Hemochromatosis Treatment|journal=Macromolecular Bioscience|year=2020|volume=20 |issue=12 |
===CO<sub>2</sub> Capture from Ambient Air===
Anion exchange resins readily absorb CO<sub>2</sub> when dry and release it again when exposed to moisture.<ref name="wang1">{{cite journal | last1=Wang|first1=Tao|last2=Liu|first2=Jun|last3=Fang|first3=Mengxiang|last4=Luo|first4=Zhongyang|title=A Moisture Swing Sorbent for Direct Air Capture of Carbon Dioxide: Thermodynamic and Kinetic analysis | journal=Energy Procedia | volume=37 | date=2013-01-01 | issn=1876-6102 | doi=10.1016/j.egypro.2013.06.538 | pages=6096–6104 | doi-access=free|bibcode=2013EnPro..37.6096W }}</ref> This makes them one of the most promising materials for direct carbon capture from ambient air,<ref name="wang2">{{cite journal | last1=Wang | first1=Xueru | last2=Song | first2=Juzheng | last3=Chen | first3=Yan | last4=Xiao | first4=Hang | last5=Shi | first5=Xiaoyang | last6=Liu | first6=Yilun | last7=Zhu | first7=Liangliang | last8=He | first8=Ya-Ling | last9=Chen | first9=Xi | title=CO2 Absorption over Ion Exchange Resins: The Effect of Amine Functional Groups and Microporous Structures | journal=Industrial & Engineering Chemistry Research | publisher=American Chemical Society (ACS) | volume=59 | issue=38 | date=2020-08-27 | issn=0888-5885 | doi=10.1021/acs.iecr.0c03189 | pages=16507–16515| s2cid=225232043 }}</ref> or [[direct air capture]], since the moisture swing replaces the more energy-intensive temperature swing or pressure swing used with other sorbents. A prototype demonstrating this process has been developed by [[Klaus Lackner]] at the [[Center for Negative Carbon Emissions]].
==See also==
Line 99 ⟶ 117:
==Further reading==
* {{cite web | title = Ion Exchange Chemistry and Operation | url = http://www.remco.com/ix.htm | publisher = Remco Engineering | access-date = 2014-05-16 | archive-url = https://web.archive.org/web/20140220030234/http://www.remco.com/ix.htm | archive-date = 2014-02-20
* {{cite book|author=Friedrich G. Helfferich|title=Ion Exchange|url=https://books.google.com/books?id=F9OQMEA88CAC|year=1962|publisher=Courier Dover Publications|isbn=978-0-486-68784-1}}
* Ion Exchangers (K. Dorfner, ed.), Walter de Gruyter, Berlin, 1991.
Line 106 ⟶ 124:
* [https://web.archive.org/web/20071024135619/http://ionexchange.books.kth.se/ A. A. Zagorodni, Ion Exchange Materials: Properties and Applications, Elsevier, Amsterdam, 2006.]
* Alexandratos S D . Ion-Exchange Resins: A Retrospective from Industrial and Engineering Chemistry Research. Industrial & Engineering Chemistry Research, 2009.
* Catalyst system comprising an ion exchange resin and a dimethyl thiazolidine promoter, Hasyagar U K
{{Authority control}}
| |||
