The inhibition effect mechanisms of four scale inhibitors on the formation and crystal growth of CaCO(3) in solution

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 CaCO(3) in solutions. According to concentrations of Ca(2+) in solutions, the sequence of inhibition effects of scale inhibitors on formation of CaCO(3) in the solution was PESA > PASP > HPMA > PAA. Characterization of CaCO(3) crystals by XRD and a laser particle size analyzer indicated that the sequence of inhibition effects of scale inhibitors on crystal growth of CaCO(3) in solutions was PESA > HPMA > PASP > PAA. Interaction energies between the scale inhibitor molecule and Ca(2+), and between the scale inhibitor molecule and the CaCO(3) (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 Ca(2+) was derived from differences of number and the Mulliken population values of the chemical bonds which formed between the inhibitor molecule and Ca(2+) and between the inhibitor molecule and the CaCO(3) surface.