Defluoridation from aqueous solution using stone dust and activated alumina at a fixed ratio

Easily available stone dust and alumina were acid activated, mixed in the ratio of 9:1 and studied for fluoride removal capacity. Batch and continuous studies were performed to test the efficiency of the adsorbents. Batch study revealed that the mixed adsorbents can remove up to 19.30 mg fluoride per gram of mixed adsorbent and is best removed at pH 6.5. Adsorption studies showed that the mechanism of adsorption is physical sorption. Flow rate plays a significant role in removing fluoride. Breakthrough study of a continuous operated unit tested at three different flow rates showed that decreasing efficiency took place at higher flow rate. The regeneration study shows that this adsorbent can be desorbed following a simple base–acid rinsing procedure.