Monte Carlo simulation for guar and xanthan gums as green scale inhibitors

Scale formation is a serious problem in water systems where it causes process fouling and interruption. Guar and xanthan gums are naturally occurring and environmentally safe carbohydrate polymers. In an attempt to investigate their antiscaling effect, Monte Carlo (MC) simulation method was employed to screen their tendency to adsorb on growing scale crystals. This study was performed on calcite (CaCO3) and anhydrite (CaSO4) crystals. Molecules of both polymers show a tendency to adsorb on both salts. Adsorption tendency of gum polymers on both minerals is expressed in terms of the values of adsorption energy calculated from Monte Carlo simulation method. The effect of polymerization degree and the number of water molecules on both adsorption energy and deformation energy is involved. MC observations indicate that Xanthan demonstrates a higher tendency for adsorption on calcite surface than guar while guar shows a higher tendency for adsorption on anhydrite.