【作者】 高华生；

【导师】 谭天恩；

【作者基本信息】 浙江大学 ， 化学工程， 2001， 博士

【摘要】 控制释放玻璃（CRG）是用途广泛的控制释放材料。本文研究磷酸盐CRG的释放动力学特性及其作为工业循环冷却水系统控制释放水处理剂的技术可行性。 磷酸盐玻璃的组成决定其化学稳定性，构成影响磷酸盐CRG释放速率的内部因素。采用表面失重法测定样品在30℃去离子水中的溶解速率，研究化学组成影响磷酸盐CRG化学稳定性的规律。结果表明，二元磷酸钠CRG的化学稳定性以40Na₂O·60P₂O₅玻璃为最好；在此基础上，引入适量的CaO或Al₂O₃，能使化学稳定性显著改善；而引入B₂O₃或SiO₂，都使化学稳定性降低。样品的红外吸收光谱分析结果说明，当磷酸盐CRG的化学稳定性得到改善时，玻璃网络结构中[PO₄]四面体上非桥氧与金属离子的结合键及[PO₄]四面体之间由桥氧构成的P-O-P链的强度增加。 介质性质和环境条件构成影响磷酸盐CRG释放速率的外部因素，磷酸盐CRG的溶解机理决定其释放特性。试验结果表明，25Na₂O·25CaO·50P₂O₅玻璃在水溶液中均匀溶解，溶解反应的活化能约为79kJ/mol；溶解速率随溶液酸性的增强而迅速增大，随溶液碱性的增强而缓慢降低。溶液中的聚磷酸盐和二价金属离子对磷酸盐玻璃的溶解过程，分别产生促进作用和抑制作用；磷酸盐CRG在水溶液中的溶解释放，是一个反应控制的传质-反应过程。对溶解机理的探讨表明，玻璃表面水化层的形成和移动速率取决于水分子在玻璃内部的扩散、渗透速率，水化反应的实质是钠离子从磷酸盐网络上发生离解反应，玻璃的溶解是通过水化层中磷酸盐网络的P-O-P链断裂实现的；玻璃-水界面上聚磷酸盐与二价金属离子的螯合反应，是溶液中聚磷酸盐浓度和溶液的水质硬质影响磷酸盐CRG溶解速率的主要因素。 水解反应是影响聚磷酸盐水处理剂缓蚀阻垢性能的重要因素。SHMP的静态水解试验和25Na₂O·25CaO·50P₂O₅玻璃的溶解-水解试验的结果表明，水解反应的活化能在90～100kJ/mol之间；随溶液水质硬度的增大，水解反应加速、活化能降低。磷酸盐CRG的连续释放可显著降低溶液中聚磷酸盐的水解率，温度对水解反应速率的影响比对溶解反应的影响更大。采用“房室模型”对循环冷却水系统药物动力学进行了分析，可以证明采用控制释放投药方式有利于敞开式循环冷却水系统中水处理剂浓度和水解率的稳定控制，实现真正的稳态操作运行。 循环冷却水中型动态模拟试验结果表明，磷酸盐CRG水处理剂具有良好的缓蚀阻垢性能，可以满足《GB 50050-95工业循环冷却水处理设计规范》对敞开式循环冷却水系统水质处理效果的要求。在工艺系统稳定运行的条件下，可实现聚磷酸盐浓度和水解率的稳定控制。连续排污以控制浓缩倍数是保证磷酸盐CRG水处理剂的稳定释放、实现水处理剂浓度的稳定控制，并减轻水解反应危害的重要前提。 磷酸盐CRG作为载体可实现无机抗菌离子的控制释放。当Ag₂O含量不超过n 浙江人学博I：学位论义一4 mol％时，磷酸盐Ag－CRG的溶解速率随A＆O引入量的增大而降低。银离于溶液平皿抑菌试验和旋转挂片试验的结果表明，银离子具有良好、持久的抑菌和杀菌作用，在水中的最低有效抑菌浓度为 SX 10’‘mg／L；增大溶液中的银离子浓度使碳钢挂片的腐蚀速率增大，而微量聚磷酸盐能有效抑制银离子对碳钢的电偶腐蚀、获得良好的缓蚀效果。试验证明，AgCRG可以同时稳定释放出聚磷酸盐和银离子，具有明显的抑菌效果和缓蚀效果。 本文研究结果表明，用磷酸盐CRG可制成具有缓蚀．阻垢．抑菌作用的多功能控制释放水处理剂，利用CRG的均匀溶解和匀速释放，实现自动恒速投药，具有操作简单、维护方便等特点，可大幅度减轻水质监测和投药操作的工作量，在中小型工业循环冷却水系统的水质处理中具有良好的应用前景。更多还原

【Abstract】 Literatures of controlled release technology were reviewed. The Comvlete Erosion Controlled Release Systems are characterized with the special advantages of 0-order release kinetics and no need of operation to remove the carrier when the release is complete. Controlled release glasses (CRGs) are the most suitable carriers for the release of inorganic metal ions and have found applications in agriculture, veterinary pharmacology and medical treatment. The release characteristics of phosphate CRGs and their prospective applications as controlled release water treatment agents are investigated in this paper, which includes the following parts. The chemical durability of phosphate glass is highly dependent on its composition, which comprises the internal factor of release kinetics of phosphate CRGs. Leach tests were conducted in deionized water at 30C in which the dissolution rates of specimens were measured by weight loss method. Results show that the 40Na2O . 60P,05 glass has the lowest dissolution rate among the Na2O-P2O~ binaiy glasses. On the basis of this composition, the durability of CRGs can be further improved by substitution of divalent metal oxides such as CaO for Na20 or trivalent metal oxides such as Al203 for P205, but deteriorated by introducing B203 or Si02 into the glass composition. FTIR spectra shows that the structural change related to the improvement of durability caused by composition adjustment includes strengthened M擮 bond on the [P04] tetrahedron formed by the non-bridging oxygen with the metal ions introduced and the P-O-P bond formed by the bridging oxygen between 2 [P04] tetrahedrons. The nature of solvent and experimental conditions comprises the external factors of the release kinetics of phosphate CRGs, which depends on the dissolution mechanism of phosphate glass. Results of leach test under different conditions show that the 25Na2&25CaO5OP2O5 glass dissolves congruently in deionized water, with an activation energy of about 79 kJ/mol. Its dissolution rate increases dramatically as the pH of solution decreases, and decreases slowly as the pH of solution increases. Sf-IMP or CaCl2 in solution have accelerating or decelerating effect, respectively, on the dissolution of phosphate glasses. The fact that the dissolution rate is not obviously affected by the stirring speed of solution implies that the mass transfer rate of the dissolution process of phosphate glass is controlled by the chemical reaction of dissolution itself. Discussions on the mass transfer-reaction behavior of dissolution mechanisms show that the nature of the reaction taking place in the hydrated layer is the dissociation of Na~ ions from the phosphate chains under the effect of the penetrating water molecules, rather than the generally accepted reaction of Na-H ion exchange. The velocity of formation and development of hydrated layer depends on the diffusion rate of water molecules in glass. The dissolution of glass is realized by the breakage of P-0-P bonds in the phosphate network in the hydrated layer followed by the disentanglement of phosphate chains into water solutions. The chelating ability of polyphosphate with divalent cations has great influence on the dissolution rate of phosphate CRGs and is found responsible for the accelerated or decelerated dissolution of the glass in SHMP or CaCl2 solutions, respectively. The hydrolysis reaction has been one of the main restrictions of polyphosphates as corrosion and scale inhibitors in cooling water systems. Static hydrolysis test of SHMP and dissolution-hydrolysis test of 25Na2O?5CaO~50P2O5 were conducted. Results show that the hydrolysis更多还原