羟基磷灰石溶解机理的研究

目的:研究羟基磷灰石(Hap)的溶解机理。方法:采用分子动力学对HAp在水分子层作用下的溶解过程进行计算。对HAp在不同pH值溶液中的表面Zeta电位进行测定,并进行HAp去除Pb2+实验,由此来对计算结果进行讨论和验证。结果:HAp在水溶液的溶解过程中表面羟基发生脱离溶入水中;表面Ca2+由于羟基的脱离,减少了与HAp结构的联系,并由表面溢出至水层中;次表面羟基发生倒转与c轴成一定角度;表面磷酸基团也脱离出来成为磷酸根离子,次表面磷酸基团的磷氧键向下倾斜;溶解作用使得HAp的表面为负电位。结论:所获溶解机理是合理的,羟基在HAp在水溶液中的溶解起着重要的作用。

Studies on Mechanism of Hydroxyapatite Dissolution

Objective： In this paper, the mechanism of hydroxyapatite （HAp） dissolution is studied. Method： First, molecular dynamics （MD） is used to simulate the dissolution process of HAp in water. Then, the Zeta-potentials varying with pH value of the solutions and the experimental results about the removal of aqueous lead ions by HAp are used to verify the simulation. Result： The simulations show that the detachment of hydroxyl groups from surface of HAp occur during the dissolution process, because of which the calcium ions in the surface layer of HAp dissolve into water. The simulations also show that the reversal of hydroxyl groups in subsurface layer of HAp occur to be at an angle to c axis. Also, the surface phosphate groups are free and the P-O bonds incline downward from c axis. The dissolution make the surface potentials of HAp be negative. Conclusion： The Zeta-potentials and the experimental results verify the simulation.