Preparation of Calcium and Magnesium Hydrogen Phosphates from Natural Dolomite and Their Sorptive properties

摘要

The reaction of dolomite with 10-20/100 phosphoric acid was studied by x-ray diffraction and chemical analysis in a wide range of dolomite concentrations in tthe reaction system. The structure, composition, and sorption capacity of the reaction products were determined. The reaction was shown to yield aw mixturre of calcium hydrogen phosphate, CaHPO_4. 2H_2O, with the brushite structure and magnesium hydrogen phosphate, MgHPO_4.3H_2O, with the newberyite structure. The sorption capactiy of the reaction product for pb ions was up to 19 mg-equiv/g. With 10/100 H_3PO_4 at an initial dolomite concentration of 0.17 g/ml, a near-theoretical reaction yield was attained.