Simultaneous removal of metals Cu2+, Fe3+ and Cr3+ with anions SO42- and HPO42- using clinoptilolite

In the present study the effect of SO42- and HPO42- on ion exchange of Cu2+, Fe3+ and Cr3+, on natural clinoptilolite is examined under normality of 0.01 N, temperature of 25 +/- 2 degreesC and pH 2-2.5 after four days of equilibration. It is observed that Cu2+ uptake is significantly decreased in the presence of HPO42- and SO42. The observed effect is less significant for Fe3+ and Cr3+ in the presence of SO42- and HPO42- respectively. This could possibly be due to the metal- anion complex formation and the nature and charges of the complex species present. Blank solutions show precipitation in the case of Fe3+/HPO42- solution, leading in complete removal of Fe3+ from solutions. Precipitation along with ion exchange is resulting in higher removal of Fe3+ from the solution than ion exchange or precipitation alone. Finally, anion co-removal is significant, reaching 80% for HPO42- ions. (C) 2003 Elsevier Inc. All rights reserved.