The present study aims to examine a selective crystallization method for boric acid (H{sub}3BO{sub}3) and sodium tetra borate decahydrate (Na{sub}2B{sub}4O{sub}7·10H{sub}2O, borax) from the boric acid solution. The substances formed from the boric acid solutions at different pH were identified. Consequently, boric acid crystals were formed from boric acid solutions adjusted to pH{sub}0=1-7, whereas borax crystals were formed from the boric acid solutions adjusted to pH{sub}0=8-12. To evaluate both crystal amounts the concentration change of the boric acid solutions at different pH were also examined. In the range of pH{sub}0=8-12 the boric acid solution adjusted to pH{sub}0=9.5 showed the maximum concentration change, therefore the crystal amount and crystal formation rate was at a maximum. Moreover, in the range of pH{sub}0=1-7 the concentration change increased as the pH decreased.
展开▼
