LAUSR

Abstract The desulfuration of fume gas using ZnO slurry is a cleaner process because the SO 2 from exhaust is transformed to a valuable ZnSO 4 solution, and the ZnSO 4 solution can then be reused in industrial processes. However, the existence of fluoride (F) in the cleaner process severely hinders the reuse of the ZnSO 4 solution. In this study, an innovative, targeted and simple technique using in situ Fe(III) in the actual ZnSO 4 waste liquid for the removal of F was proposed. The results indicated that in situ Fe(III) exhibited a good performance in the removal of F and an increase of Fe concentration is beneficial to the removal of F. The active component in the removal of F was identified as a type of hydroxylation ferric sulfate, schwertmannite, which formed under the strong acidic condition. The removal mechanism of F was recognized as an ionic-exchange with the OH − groups from coordinated FeOH −1/2 and Fe 2 OH 0 and SO 4 2− groups in schwertmannite as well as electrostatic adsorption interactions. Based on above principle, the concentration of F in the actual ZnSO 4 solution was successfully reduced to below 50 mg/L, bringing the ZnSO 4 solution up to the recycling standard. This research can be used to guide the effective removal of F from the waste liquid with high acidity, salinity and heavy metals, in the practice.