Preparation And Adsorption Behavior Of Silica Gel Loaded With ZrO₂ Towards Removal Of Fluoride From Water

Fluoride is the necessary element for human health. Drinking water with certain concentration of fluoride can prevent dental caries, but drinking water with excessive fluoride in the long run may affect human health. It is important to investigate the cost-effective methods of defluoridation from drinking water. In this paper, the silica gel loaded with ZrO₂ is prepared, and its adsorption performance for fluoride removal is evaluated. Experimental results show that it is a new high-effective and relatively low-cost adsorption material. It will have a bright application foreground, not only because of its great affinity to fluoride and its rapid speed of defluoridation, but also because of its higher removal capacity .In this paper, the silica gel loaded with ZrO₂ is prepared by dipping-filtrating-baking process. The conditions of preparing adsorbent such as temperature of baking, the granularity of silica gel, the ratio of solid to liquid, concentration of ZrO₂ solution, and so on are investigated. Orthogonal experiment is exerted on the basis of many single factor experiments, and the best condition of preparation is obtained. In addition, the silica gel loaded with ZrO₂ is also prepared by dipping-evaporating-baking, and experimental results show that removal capacity of the second adsorbent excels the first adsorbent's capacity.The behavior of adsorbent for removing fluoride is studied by static method. The factors influencing the adsorption capacity are discussed. Experimental results show that the inference of pH is significant on adsorption capacity. The optimum pH for adsorption is 3⁴ . The adsorption capacity decreases rapidly with pH increasing from 4 to 9. When pH value is higher than 10 the adsorbent can hardly adsorb. The results show that the silica gel loaded with ZrO₂ is suitable for disposal of acidity solution. When the temperature of adsorption changes from 20℃ to 50℃, the adsorption capacity keeps stabilization, which shows that the influence of temperature is very little on adsorption capacity. Largest adsorption capacity is obtained within half an hour contact-time, which shows that the adsorbent has great affinity to fluoride and rapid speed of defluoridation within a short contact-time . We use 0.3g adsorbent to deal with 100mL of fluoride...