SeF4 and SF4 fluorination of BPL activated carbon surfaces

Fluorination of the surfaces of activated carbons has been proposed as a method to enhance the resistance of the activated carbon to the unwanted adsorption of water. In addition, the fluorination would increase the efficiency of the activated carbon to adsorb hydrophobic compounds. This study details the fluorination of BPL activated carbon with two selective fluorinating agents, selenium tetrafluoride (SeF4) and sulfur tetrafluoride (SF4). SeF4 and SF4 have been used previously to replace oxygen atoms with fluorine atoms. The BPL activated carbon was oxidized with nitric acid to increase the number of surface oxides present on the activated carbon. These surface oxides were the intended targets for the SeF4 and SF4 fluorinations. Results presented in this report include the reaction procedures used and the elemental chemical analysis of the products. Total fluorine content of the products and changes in the atomic percentages of carbon and oxygen from before the fluorination reactions to after reactions were completed are reported. Also, results of water uptake, surface acidity and surface area analysis studies are provided. (C) 1997. Published by Elsevier Science Ltd.