Lewatit TP 260 is a weakly acidic, macroporous cation exchange resin chelatingwith  aminomethylphosphonic acid functional groups. It has a high operating capacity and very good mechanical and chemical stability in acid and alkaline media.

Business Unit
Ion Exchange Resins

Properties and benefits
Primary areas of application are :

• Secondary brine purification e.g. for the removal of alkaline earths from brine used in the alkali chloride membrane electrolysis process.  Lewatit TP 260 eliminates residual amounts of calcium and magnesium, particularlydownstream the conventional purification processes (precipitation byhydroxides and carbonates) in the pH range of 8 - 11.  Lewatit TP 260 can be used to purify brine at pH 8 - 11 and 60 - 80 °C. The operating capacity depends greatly on the pH of the brine. At pH 10 it is about twice as high as at pH 8. At pH 10 and 1 - 5 ppm calcium, a capacity up to 14 g Ca/l Lewatit TP 260  (calculated on the volume of the resin in the total sodium form) is obtained. The residual calcium values are well below 10 ppb, even at specific flow rates up to 40 bed volumes/hour. The use of two columns in series provides greater security. Chlorine (Cl2) levels in the feed brine should be kept below 0.1 ppm. Otherwise the life time expectation will be significantly decreased.
  

• Extraction / Recycling of heavy metal ions from leaching solutions, e.g. uranium from crude phosporic acid, from pickling and surface treatment baths e.g., iron, nickel and zinc from concentrated sodium gluconate solutions,from waste waters of the metals finishing industry e.g. tin and lead from rinse water of the printed circuit manufacturing.
  
  

The adsorption of heavy metal cations from aqueous solutions is in accordance with the following selectivity sequence: UO22+ > Pb2+ > Cu2+ > Ni2+ > Cd2+ > Co2+ > Ca2+ > Mg2+ > Sr2+ > Ba2+ > alkalimetals.

For the extraction of heavy metals from copper onwards in the selectivity sequence shown above, Lewatit  TP 260 has to be conditioned with caustic soda solution after every regeneration cycle / prior to every exhaustion cycle.

For this purpose approx. 50 % of the resins total capacity needs to be converted into the sodium form.