有机膦酸化合物阻垢缓蚀性能的量子化学研究

通过量子化学计量，探讨了乙烷－1，1－二膦酸（1，1－EDPA）、乙烷－1，2－二膦酸（1，2－EDPA）与羟基乙叉二膦酸（HEDP）三种结构相似的有机膦酸阻垢缓蚀剂分子结构与阻垢缓蚀性能之间的构效关系。计算结果显示，在阻垢性能方面，三种膦酸分子膦羧基团中氧原子呈负电性，这使得膦羧基易与晶面上的钙离子发生静电交互作用。且1，1－EDPA与HEDP分子中两个膦氧离子间距与方解石有关晶面上钙离子间距匹配，因而显著加强了阻垢剂分子与特定晶面的吸附行为，起到了碳酸钙晶体的阻垢效能，而1，2－EDPA不具有匹配的特征。在缓蚀性能方面，计算得到的三种分子最高占据轨道能量从高到低依次为1，2－EDPA；HEDP；1，1－EDPA。配合计算膦羧基团中膦中心原子对前线轨道电子云密度分布的贡献、磷原子2p轨道电子的富集程度，通过分析缓蚀剂分子与金属形成配价键的难易性，探讨了这三种有机膦酸分子缓性能差异的微观成因。

Quantum Chemistry Study on Microscopic Mechanism of Scale and Corrosion Inhibition for Organic Phosphonic Acid

Quantum chemistry calculations have been performed for three organic phosphonic acids,ethane-1,1-diphosphonic acid(1,1-EDPA)?ethane-1,2-diphosphonic acid(1,2-EDPA) and 1-hydroxyethylidene-1,1-diphosphonic acid(HEDP),which have very similar structures.Molecular structures?electronic state density?HOMO energy levels and orbital coefficients have been calculated by using CNDO/2 method.Quantum chemistry calculations indicate that only phosphonate oxygens in these three molecules exhibit negatively charged,which demonstrates that strong electrostatic interaction between these functional groups and calcium cations on the calcite surface may occur,if the distance between two phosphonate oxygens and neighbour calcium cations are exactly matched.The coulombic interaction results in the excellent scale inhibition efficiency of 1,1-EDPA and HEDP compared to 1,2-EDPA.In concern with their corrosion inhibition effectiveness,the calculated HOMO energy levels decrease in order of 1,2-EDPA,HEDP and 1,1-EDPA,which satisfactorily compared with their measured corrosion inhibition efficiency.The formation of the chelate bonds between organic molecules and metal surface has been studied by analysising the contribution of each Atom Orbital to the density of the electronic charge in HOMO and electron orbital population of 2 p orbital electrons of phosphorus atoms.