The removal of Cr(VI) from aqueous solutions using zinc extraction residue

This study deals with the removal of Cr(VI) from aqueous solutions by using filter cake known as zinc extraction residue (ZER) generated as a by product in a zinc production plant located in Kayseri-TURKEY. It was found that ZER, which is rich in lead compounds, has a great affinity for chromate ions. The Cr(VI) removal yield decreased with increasing initial concentration of Cr(VI) solution. An increase in the dosage of ZER caused an increase in the removal yield and the concentration of Pb, Cd and Zn released from ZER into the treated solution. The effect of temperature showed the removal process is endothermic. The removal process was highly pH dependent. 100 % removal of Cr(VI) was obtained at initial pH about 5.0 and 11.0 for the initial Cr(VI) concentration of 100 mg l−1 at 25 °C and 5 mg l−1 ZER dosage for contact time of 60 min. The removal percentage of Cr(VI) declined at pHs other than those mentioned above. Minimum removal (26.5 %) was observed at initial pH value of 3.05. XRD analysis showed that low-solubility lead chromates were formed in the removal process