ADSORPTION PROPERTIES OF HYDROXYAPATITE PRODUCED FROM FISH BONES FOR FLUORINE

Fluorine is contained in most rocks in the earth's crust, and the occurrence of groundwater contamination by fluorine is most likely of natural origin. More than 200 million people worldwide are estimated to be forced to use drinking water with fluorine levels exceeding the WHO guideline value, and 60 to 70 million people are reported to suffer from fluorosis in 25 countries worldwide. In Asian countries, groundwater is the main source of drinking water. The removal of fluorine from groundwater is urgently needed to enable us to drink it safely. General fluorine removal technologies include chemical precipitation and adsorption methods. However, there are problems in terms of treatment capacity and cost. On the other hand, bone charcoal made by carbonizing animal bones such as cattle bones, which are food waste, is widely used as a fluorine adsorbent. This is because hydroxyapatite, the main component of bones and teeth, easily absorbs fluorine. Thus, in this study, fish bones, which are fishery waste, are focused on. The reason is that hydroxyapatite produced by calcining fish bones may have the capacity to adsorb fluorine. Therefore, immersion and shaking tests are conducted by using the hydroxyapatite produced from fish bones as an adsorbent, and its adsorption performance for fluorine is examined. The test results indicated that fluorine adsorption was dependent on pH and that the hydroxyapatite produced from fish bones could adsorb more fluorine by maintaining the pH at 3.