模拟3种有机膦系阻垢剂与方解石(104)面的相互作用

Modeling the interaction of three phosphonates with the Calcite(104) face

通过pH曲线实验研究了乙二胺四亚甲基膦酸(EDTMP),己二胺四亚甲基膦酸(HDTMP)和二乙烯三胺五亚甲基膦酸(DTPMP)对碳酸钙垢的阻垢性能,在相同的加药浓度下阻垢性能强弱顺序为:DTPMP>EDTMP>HDTPM。同时采用周期性边界条件下的分子动力学方法,模拟研究了在水分子存在条件下各阻垢剂与方解石(104)面的相互作用,得到了相应的结合能和原子间距离等参数。结果表明:阻垢分子膦酸基团中的双键氧与碳酸钙中的Ca^(2+)形成的强静电相互作用力对吸附起了主导作用,同时膦酸基团中的氢与晶面中的氧形成了氢键,加强了吸附效果。综合考虑各分子在晶面(104)上的吸附效果,其结果与实验相符合;从分子中膦酸基团作用个数也可看出,HDTMP只有一个膦酸基团靠近晶面,因此作用力也是最弱的。

The effect of three phosphonic acids （ethylene diamine tetra（methylene phosphonic acid）, EDTMP; hexamethylene diamine tetra（methylene phosphonic acid）, HDTMP; and diethylene tdamine penta（methylene phosphonic acid）, DTPMP on the growth of CaCO3 has been investigated by pH curve method （pHCM）. The result shows the inhibitor effectiveness： DTPMP 〉 EDTMP 〉 HDTMP. Meanwhile, the interaction of three phosphonic acids with the calcite （104） surface has been also studied by means of molecular dynamic simulation under the periodic boundary condition in water environment. The results indicate that strong electrostatic interactions between the oxygen atom in phosphonate functional groups and the Ca^2＋ of the calcite （104） face play a dominant role in their adsorption, and the formation of hydrogen bond enhances the strength of interaction of the surfaces with the phosphonates. For the calcite （104） surface, the binding energy has a sequence in agreement with the pHCM experiment. The weakest inhibition of CaCO3 is HDTMP because of the only one phosphonate group in contact well with the surface.