The inhibitory effects of four inhibitors on the solution adsorption of CaCO(3) on Fe(3)O(4) and Fe(2)O(3) surfaces

This study presents the inhibitory effects of four scale inhibitors, including polyacrylic acid (PAA), hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA) and polyaspartic acid (PASP), on the adsorption of CaCO(3) on the surfaces of Fe(3)O(4) and Fe(2)O(3). Samples were characterized using SEM and EDS and the average atomic number ratios of Ca/Fe were calculated. Inhibition effects followed the trend: PESA > PAA > PASP > HPMA and PESA > PASP > HPMA > PAA for Fe(3)O(4) and Fe(2)O(3), respectively. Molecular dynamics simulations based on the adsorption model of the scale inhibitor on the surface and calculations of the adsorption energy between the scale inhibitor molecule and the surface revealed that the relatively high scale inhibitory effect is due to low adsorption energy between the inhibitor molecule and the surface. Density Functional Theory (DFT) calculations of the model after adsorption revealed that the relatively low adsorption energy depends on the number of H-O bonds formed as well as those with higher Mulliken population values between the scale inhibitor and the surface.