The Mechanism Of Inhibition Of The Crystallization Of Calcium Carbonate With Organic Phosphonastes

The mechanism of interaction for organic phosphonastes on the CaCO3 is investigated by using the Molecular Dynamic simulation techniques and quantum chemical calculation.The structures of seven organic phosphonastes (i.e. AMP,MDP,HEDP,HPDP,ATMP,PBTC and EDTMP) and its analogs were optimized by means of density functional theory (DFT) of quantum chemical calculation, at the level of B3LYP with the 6-31G* basis set with GaussianO3 software. The most stable configurations were obtained by this method in neutral and alkaline conditions. Some quantum parameters were calculated, such as bond lengths, bond angles, dihedral angles, atomic charges, highest occupied molecular orbital energies and lowest unoccupied molecular orbital energies△E and so on. The interaction of the crystallization of calcium carbonate was analyzed from the parameters above.On the basis of the quantum chemistry, the molecular simulation method was employed to investigated the morphology of calcite, aragonite and vaterite. The simulation results were according with the experiments of SEM. The interactions between organic phosphonastes and surfaces including the calcite step surfaces, aragonite and vaterite main surfaces have been simulated by Molecular Dynamics method. The equilibrium configurations of organic phosphonastes adsorbed on these surfaces, binding energy, deforming energy and radius distribution function were obtained to predict the order of the inhibition for the organic phosphonastes. The adsorption of three phosphonic acids named ATMP, HEDP and EDTMP on the main surface of calcite in an aqueous environment, which is important in the geological environment. The result is consistent with the scale inhibition experiment.