Iron, Copper, and Nickel Removal with Calcium Hydrogen Phosphate and Calcium Pyrophosphates in Solution

Abstract

Calcium phosphate is an important material used in ion exchangers and adsorbents. In this work, calcium hydrogen phosphate dihydrate, CaHPO 4 •2H 2 O, was prepared from calcium nitrate solution and phosphoric acid. This phosphate transformed to calcium hydrogen phosphate un-hydrate, CaHPO 4 , by heating at 200ºC, and calcium pyrophosphate, Ca 2 P 2 O 7 , by heating at 400 and 700ºC. These calcium phosphates were used to remove trivalent iron cation, Fe 3+ in solution. Samples without heating and those heated at 200ºC 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, Cu 2+ and Ni 2+. The removal ratios of copper and nickel cations were lower than those of iron cation.

Marine-Derived Biowaste Conversion into Bioceramic Membrane Materials: Contrasting of Hydroxyapatite Synthesis Methods

“…The existence of calcium iron hydrogen phosphate or Ca 9 FeH(PO 4 ) 7 is also another advantage, although its benefit for bioceramic ultrafiltration membranes is still unknown. The compound has a high capability as an absorber from, e.g., in UV light, as cosmeceutical, or used in water or wastewater treatment [76][77][78][79].…”