イオン交換樹脂を含む懸濁水への難溶性無機化合物の溶解 (第2報)
リン酸カルシウム化合物
1988 年 96 巻 1117 号 p. 914-919
詳細
1988 年 96 巻 1117 号 p. 914-919
Following the previous paper on the dissolution of hydroxyapatite (HAp), the dissolution mechanism of other calcium phosphate compounds was studied for the filtrate after treating ca. 300mg of the sample powders with 0-3.0g of H-R (strongly acidic ion exchange resin, H-form) in aqueous media. Dissolved amounts of Ca, PO4 and P2O7 were determined using ion chromatography and isotachophoresis. Variations of pH value and specific conductivity during the dissolution process were also measured to compare the dissolution rate. The results obtained are summarized as follows;
(1) Ca3(PO4)2(TCP), Ca8H2(PO4)6⋅5H2O(OCP), Ca4(PO4)2O(TeCP) and Ca2.67Al0.22(PO4)2(β-TCP*, a solid solution of AlPO4 and TCP) dissolve in a similar way to HAp to give Ca(H2PO4)2 according to the Eq. (1) and is followed by the successive ion exchange reaction Eq. (2), for example, Ca3(PO4)2+4(H-R)→Ca(H2PO4)2+2(Ca-R2) (1) Ca(H2PO4)2+2(H-R)→Ca-R2+2H3PO4 (2)
(2) Reaction between Ca2P2O7 and H-R can be expressed by the following equation to yield a new soluble compound CaH2(H2P2O7)2, 2Ca2P2O7+6(H-R)→CaH2(H2P2O7)2+3(Ca-R2)
