Dissolution mechanism and release kinetics of phosphate controlled release glasses in aqueous medium
Dissolution mechanism and release kinetics of phosphate controlled release glasses in aqueous medium
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DOI：
10.1016/j.jconrel.2003.12.031
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发表时间：
2004-04-16
影响因子：
10.8
通讯作者：
Wang, DH
中科院分区：
文献类型：
--
作者：
Gao, HS;Tan, TN;Wang, DH
研究了不同条件下磷酸盐控释玻璃在水介质中的溶出性能。结果表明，磷酸盐CRG在去离子水中溶解一致。其溶出速率与溶液的pH值、温度、介质中磷酸根离子和钙离子的浓度有关，而与溶液的搅拌速度无关。分析表明，磷酸盐玻璃的溶解是一个反应控制过程。对溶解机理的讨论表明，水化层中的反应本质是在渗透水分子的攻击下，Na+离子从磷酸盐链上解离而成。水化层的形成和发展速度取决于水分子在玻璃中的扩散速度。溶解是通过水化层内磷酸盐网络中P-O-P键的断裂实现的。聚磷酸盐与二价阳离子的螯合能力在磷酸盐CRG的溶解过程中起着重要的作用，并被发现负责加速或减速溶解的CRG在六偏磷酸钠（SHMP）或氯化钙溶液中，分别。(C)2004 Elsevier B. V.保留所有权利。
Leach test of a phosphate controlled release glass (CRG) were conducted in aqueous medium under different conditions. Results show that the phosphate CRG dissolves congruently in deionized water. Its dissolution rate is dependent with the solution pH, temperature and concentrations of phosphate ions and calcium ions in the medium, but independent with the stirring speed of the solution. Analysis leads to a conclusion that the dissolution of phosphate glass is a reaction-controlled process. Discussions on the dissolution mechanisms show that the nature of the reaction in the hydrated layer is the dissociation of Na+ ions from the phosphate chains under the attack of the penetrating water molecules. The velocity of formation and development of hydrated layer depends on the diffusion rate of water molecules inside glass. The dissolution is realized by the breakage of P-O-P bonds in the phosphate network within the hydrated layer. The chelating ability of polyphosphate with divalent cations play an important role in the dissolution process of phosphate CRGs and was found responsible for the accelerated or decelerated dissolution of the CRG in sodium hexametaphosphate (SHMP) or CaCl2 solutions, respectively. (C) 2004 Elsevier B.V. All rights reserved.