With the new macroporous anion exchange resin Lewatit MonoPlus TP109, the specialty chemicals company LANXESS is expanding its selective resins for the removal of contaminants such as per- and polyfluoroalkyl substances (PFAS) from water. The resin will be presented for the first time at the international trade show Aquatech, which will take place in Amsterdam, the Netherlands, from 6-9 Nov 2023.
“Ion exchange resins have proved as a reliable means of removing contaminants from water. Ion exchange and adsorption processes sometimes even have a cooperative effect,” said Dr Dirk Steinhilber, technical marketing manager in the liquid purification technologies business unit at LANXESS.
He added that the Lewatit MonoPlus TP109 is “especially suitable for the purification and remediation of water with PFAS concentrations exceeding 10 parts per billion (ppb)”. “As an integral part of our range of resins, it helps us to develop custom solutions for removing PFAS,” Dr Dirk said.
In addition to its high selectivity, the macroporous resin reportedly exhibits good kinetics and high fouling resistance. The uniform bead size ensures improved hydraulics. It can be regenerated with tried-and-tested regeneration chemicals such as methanol and sodium chloride. “With higher PFAS concentrations in water, this is a benefit — because it allows the resin to be used sustainably,” Dr Dirk added.
Lewatit MonoPlus TP109 binds different PFAS and complex anions such as nitrate, bromate, chlorate and perchlorate so that they can then be removed from water. It can remove chlorate from concentrated sodium hydroxide. LANXESS also offers other selective resins for removing PFAS and that can also be combined for pre-cleaning and final polishing. The heterodisperse, gel-type, strong base anion exchange resin Lewatit TP108 DW is said to help remove PFAS — especially short-chain members of this substance class —in concentration ranges of less than 10ppb and, due to its extremely high selectivity, into the one part per trillion (ppt) range.
At a fire service training site in Australia, for example, up to 200ppb of PFAS were removed from more than 50 million litres of groundwater over many months. Due to the high usable capacity and correspondingly long service lives even in the presence of chlorides and sulfates, regeneration is not recommended for this resin. Lewatit TP108 DW is certified to Standard 61 of the NSF/ANSI/CAN and meets US requirements for contact with drinking water.
As a weak base, macroporous anion exchange resin, another selective resin — Lewatit MP62 WS — offers medium selectivity for PFAS. Due to its total capacity of more than 1.7eq/L and its high operating capacity, it pre-treats heavily contaminated leachate, such as those close to the source of contamination. This resin, too, can be regenerated, with sodium hydroxide. Finally, Lewatit K6362 is a strong base anion exchange resin that can be used for final polishing in a two-stage process, with Lewatit MonoPlus TP109 or Lewatit MP62 WS being used in the first purification stage.
