Separation of Halogens from Liquids or Gases
The Group VIIA elements (fluorine, chlorine, bromine, iodine, astatine) are commonly referred to as halogens. Halogen atoms are characterized by an electronic structure where they are missing one electron so they readily form the anion X2. Halogens also form complexes like iodide (I3-) that are strongly anionic. Halogens form oxo-acids and oxides such as chlorite (ClO2-) and perchlorate (ClO4-) that are also anionic.
F
Fluorine
Cl
Chlorine
Br
Bromine
I
Iodine
At
Astatine
Fluoride is a very low-selectivity anion so it cannot be removed from water without first removing all of the higher-selectivity anions like chloride or sulfate. Anions are removed according to their selectivity as described in the table of selectivity data.
Fluoride can be selectively removed with activated alumina. There are many suppliers available for this media.
Under acidic conditions, fluoride is present as HF and can be removed from solution with an acid absorber like AmberLyst™ A21 Resin. Under neutral to basic conditions, AmberSep™ 21K XLT Resin has the strong base functionality needed to split the salt. For streams that have a high content of organic material and are prone to surface fouling, AmberLite™ HPR9200 Cl Strong Base Anion Exchange Resin is recommended. Anions are removed according to their selectivity as described in the table of selectivity data.
Halogen acid gases cause corrosion problems in a wide variety of applications. AmberLyst™ A21 Macroporous Weak Base Anion Resin can be used to remove the corrosive compounds.
The family of synthetic compounds known as per- and polyfluoroalkyl substances (PFAS) have been in use in various applications since the 1940’s. These compounds have been used in multiple industries including textile coverings for oil and water repellency, cookware coating, formulation of firefighting foams, and in materials used in the automotive and electronics industries. More recently, detection of PFAS in groundwater sources and the issuance of a health advisory level by the U.S. Environmental Protection agency for PFAS has spurred development of treatment technologies for PFAS containing waters. Use of ion exchange resins has emerged as one of the demonstrated technologies for removal of PFAS from water. For both drinking water or groundwater treatment, AmberLite™ PSR2 Plus Ion Exchange Resin can be used as a single-use resin for PFAS removal.
Perchlorates (ClO4-) are man-made chemicals used in munitions and rocket propellants. They are highly soluble in water so they can be widely found in groundwater due to their high mobility. Once dispersed ClO4- can remain in the environment for decades as it does not readily degrade. AmberLite™ PSR2 Plus Resin can be used to bind and remove ClO4- at the ppb levels as a non-regenerated media.
Selective iodine removal from salt solutions has been described using a metal hydroxide loaded ion exchange resin.1 AmberSep™ G26 H Strong Acid Cation Exchange Resin is a tough and versatile cation resin for this application.
Under acidic conditions, halogens, and their complex oxides are acids and can be removed from solution with an acid absorber like AmberLyst™ A21 Resin. Under neutral to basic conditions, AmberSep™ 21K XLT Resin has the strong base functionality needed to split the salt. For streams that have a high organic content and are prone to surface fouling, AmberLite™ HPR9200 Cl Strong Base Anion Exchange Resin is recommended. Anions are removed according to their selectivity as described in the table of selectivity data.
Halogen acid gases cause corrosion problems in a wide variety of applications. AmberLyst™ A21 Macroporous Weak Base Anion Resin can be used to remove the corrosive compounds.
Since halogen gases (X2) are often used in a compressed form, they may be contaminated with compressor lubricants.
AmberSep™ Optipore™ V493 Polymeric Adsorbent has been shown to work well to remove these compressor lubricants from compressed gas streams2 and AmberSep™ Optipore™ V503 Polymeric Adsorbent could also be tested for comparison.