The inhibition effect mechanisms of four scale inhibitors on the formation and crystal growth of CaCO3 in solution

Changjun Li,Wuping Zhang,Chaoyi Zhang

doi:10.1038/s41598-019-50012-7

Abstract

The experimentation, molecular dynamics simulation and DFT calculation were used to study the inhibition effects of four scale inhibitors, including polyacrylic acid (PAA), hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA) and polyaspartic acid (PASP), on formation and crystal growth of CaCO3 in solutions. According to concentrations of Ca2+ in solutions, the sequence of inhibition effects of scale inhibitors on formation of CaCO3 in the solution was PESA > PASP > HPMA > PAA. Characterization of CaCO3 crystals by XRD and a laser particle size analyzer indicated that the sequence of inhibition effects of scale inhibitors on crystal growth of CaCO3 in solutions was PESA > HPMA > PASP > PAA. Interaction energies between the scale inhibitor molecule and Ca2+, and between the scale inhibitor molecule and the CaCO3 (104) surface indicated that the difference of the inhibition effects was derived from the difference in the interaction energy. The results of DFT calculation indicated that the difference between the interaction energies of these inhibitors and Ca2+ was derived from differences of number and the Mulliken population values of the chemical bonds which formed between the inhibitor molecule and Ca2+ and between the inhibitor molecule and the CaCO3 surface.

Highlights

The results of DFT calculation indicated that the difference between the interaction energies of these inhibitors and Ca2+ was derived from differences of number and the Mulliken population values of the chemical bonds which formed between the inhibitor molecule and Ca2+ and between the inhibitor molecule and the CaCO3 surface
polyacrylic acid (PAA), hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA) and polyaspartic acid (PASP) can all be adsorbed to the main growth surface of the calcite crystal, inhibiting the growth of crystals and resulting in the destruction of the regular shape of the calcite crystal[2,3,4,5,6,7,8,9,10]
We first evaluated the scale inhibition effect of four scale inhibitors based on the experimental results

Summary

Third group of experiment SD

The XRD peak of the CaCO3 (104) surface and the average volume of particle size of CaCO3 crystal are shown in Figs 9 and 10 and Table 2, respectively. As shown in Figs [6,7,8,9,10] and Table 2, in presence of scale inhibitors, the crystal growth of the (104) surface of CaCO3 was suppressed, the overall growth rate of the crystal was decelerated, and the average volume particle size was reduced The sequences of both XRD peak and the volume average particle size in solutions containing.

Inhibitor PAA HPMA PESA PASP

PESA PASP

Conclusions

Additional Information