Removal of tetrafluoroborate ion from aqueous solution using magnesium–aluminum oxide produced by the thermal decomposition of a hydrotalcite-like compound

Magnesium–aluminum oxide (Mg–Al oxide) prepared by the thermal decomposition of a hydrotalcite-like compound was found to have potential for treating NaBF4 wastewater. The Mg–Al oxide removed the BF4- and F− and H3BO3 from the NaBF4 solution. With increasing Mg–Al oxide quantity and time, the BF4- concentration decreased and the degree of BF4-, F−, and boron removal increased. The decrease in the BF4- concentration resulted from uptake by the Mg–Al oxide and not hydrolysis. The Mg–Al oxide took up F− from the solution preferentially. The Mg–Al oxide also converted the H3BO3 in the aqueous solution into H2BO3-, which it took up.