REMOVING SELENIUM(IV) AND ARSENIC(V) OXYANIONS WITH TAILORED CHELATING POLYMERS

The need for selective sorption of trace concentrations of toxic Se(IV) and As(V) oxyanions, especially in the presence of competing high concentrations of sulfate ions, is well recognized. In this regard, previous investigators have shown the advantages as well as shortcomings of the fixed-bed sorption process when activated alumina or strong-base polymeric anion exchangers are used as sorbents. The present study reports the sorption behaviors of a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites. Experimental results with the new sorbent show higher selenite and arsenate selectivities over competing sulfate ions. Anion exchange accompanied by Lewis acid-base interactions are the underlying reasons for the new sorbent's enhanced affinities toward arsenates and selenites. In several ways, the new sorbent can complement the shortcomings of activated alumina and other strong-base anion exchangers.