Zinc removal from aqueous solution using an industrial by-product phosphogypsum

The removal of zinc(II) ions from aqueous medium by phosphogypsum was examined. The removal capacity of phosphogypsum for zinc(II) ions was studied as a function of solution pH, contact time, adsorbent dosage and adsorbate concentration. Phosphogypsum was pre-conditioned with lime milk before the adsorption studies. The maximum adsorption of the zinc(II) ions on the phosphogypsum was observed at the pH values between 9.0 and 10.0. It was observed that the adsorption equilibrium was reached in 40 min and the adsorption data fitted well to Freundlich model. The adsorption capacity of phosphogypsum for zinc(II) ions was determined to be 2.57 mg g−1. The results showed that the phoshogypsum is a suitable adsorbent for the removal of zinc(II) ions from aqueous solutions.