H. Onoda, K. Sasaki
Jul 1, 2017
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Abstract
Calcium phosphate is an important material used in ion exchangers and adsorbents. In this work, calcium hydrogen phosphate dihydrate, , was prepared from calcium nitrate solution and phosphoric acid. This phosphate transformed to calcium hydrogen phosphate un-hydrate, CaHPO4, by heating at 200℃, and calcium pyrophosphate, Ca2 P2 O7, by heating at 400 and 700℃. These calcium phosphates were used to remove trivalent iron cation, Fe3+ in solution. Samples without heating and those heated at 200℃ indicated a high iron removal ratio. By the addition of these calcium phosphates and stirring for 5 minutes, a high ratio of iron cation was removed from the solution. This removal depended not only on the substitution of calcium to iron, but also on the precipitation of iron hydroxide. Calcium phosphates were also used to remove copper and nickel cations, Cu2+ and Ni2+. The removal ratios of copper and nickel cations were lower than those of iron cation.