The Effect of Accompanying Anions on Arsenate Sorption onto Selective Sorbents

Abstract

Arsenate sorption onto inorganic and composite inorganic/organic selective sorbents based on ferric oxide/oxohydroxide was tested under varying concentration of accompanying anions (chlorides, sulfates, phosphates, and silicates). Among the studied anions, phosphates showed the strongest influence on arsenic removal. Ferric oxide based sorbents were also compared to weak and strong base anion exchangers and other metal oxide (ceric oxide, zirconium oxide) based composites under the presence of accompanying anions (chlorides and sulfates). Their performance was comparable to ferric oxide composites. Ferric oxide/oxohydroxide based composites are able to take up arsenates (with capacity of tens of mmol·L−1) even at the presence of 100 mg·L−1 of chlorides and sulfates where the breakthrough capacities of weak and strong base anion exchangers dropped to less than 2% (units of mmol·L−1) of the values obtained in the absence of accompanying anions (hundreds of mmol·L−1).