Simultaneous removal of metals Cu 2+, Fe 3+ and Cr 3+ with anions SO 42− and HPO 42− using clinoptilolite

Abstract

In the present study the effect of SO 4 2− and HPO 4 2− on ion exchange of Cu 2+, Fe 3+ and Cr 3+ on natural clinoptilolite is examined under normality of 0.01 N, temperature of 25 ± 2 °C and pH 2–2.5 after four days of equilibration. It is observed that Cu 2+ uptake is significantly decreased in the presence of HPO 4 2− and SO 4 2. The observed effect is less significant for Fe 3+ and Cr 3+ in the presence of SO 4 2− and HPO 4 2− 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 Fe 3+/HPO 4 2− solution, leading in complete removal of Fe 3+ from solutions. Precipitation along with ion exchange is resulting in higher removal of Fe 3+ from the solution than ion exchange or precipitation alone. Finally, anion co-removal is significant, reaching 80% for HPO 4 2− ions.