Bone char

[…] bone chars differ greatly in surface area. It has also been shown that the various nitrogen adsorption isotherms for bone chars could be plotted on a single curve. When the volume of gas adsorbed per unit area was plotted against[…]

A drawback for the use of bone char was discovered by Bellack (40). During an investigation on the removal of fluoride with bone char on an arsenic-bearing water, Bellack observed that arsenic could also be removed by this material but that the arsenic-removal process was irreversible. Because arsenic competes with fluoride and because it cannot be stripped off by the normal caustic regeneration process, the fluoride capacity of bone char decreases with use and eventually the bone char has to be replaced. Bone char, therefore, would not be very practical for fluoride waters that also contain arsenic.

[…] bone chars. In the case of fluoridesaturated bone chars, no surface fluoride was identified and this may be due to the fact that the amount of fluorides adhering to the surface of the bone chars is below the detection limit.