Molecular dynamics simulation for interaction of PESA and acrylic copolymers with calcite crystal surfaces

The interactions between four scale inhibitors, namely, polyepoxysuccinic acid (PESA), acrylic acid–maleic acid copolymer[P(AA-co-MA)], acrylic acid–hydroxypropyl acrylate copolymer[P(AA-co-HPA)], acrylic acid–methyl acrylate copolymers[P(AA-co  -MAE)] and (104), (11¯0)surfaces of calcite crystal are simulated using a molecular dynamics (MD) method. The results show that the order of corrected binding energy of the four polymers is as follows: PESA > [P(AA-co-MA)] > [P(AA-co-HPA)] > [P(AA-co  -MAE)]; however, the interaction of polymers with the (11¯0) surface is significantly stronger (2.5 to 2.8 times) than that with the (104) surface. The binding energy is mainly provided by the ionic bond and the Coulomb interaction, which is verified by analysis of pair correlation functions. The structures of the polymers are deformed during their combining processes with the surfaces. However, the deformation energies are far less than their nonbonding energies respectively. With increasing processing temperature, both the binding energy and the corrected binding energy decrease. The simulation results agree with the static anti-scaling experimental results, which indicate the simulation is correct and reasonable. The simulation results provide theoretical knowledge to assess the performance of scale inhibitors and to synthesize new, highly effective water treatment agents.

The analysis of pair correlation function indicates that the interaction between PESA and calcite crystal involves both nonbonding and electrovalent bond interactions. Moreover, the electrovalent bond enhances the strength of the interaction between the polymer and crystal. The order of the binding energies of the four polymers with calcite crystal was as follows: PESA > [P(AA-co-MA)] > [P(AA-co-HPA)] > [P(AA-co-MAE)].Figure optionsDownload as PowerPoint slideHighlights
► The interaction between PESA, acrylic copolymers and calcite is simulated with MD.
► The interaction with (11¯0) surface is stronger (2.5 to 2.8 times) than that with (104).
► Binding energy mainly comprises the electrovalent bonds and the coulomb interaction.
► As temperature gradually increases, the binding energy becomes lower.
► The simulation results agree with the static anti-scaling experimental results.