The inhibition of precipitation of calcium carbonate scale by Eucalyptus globulus leaves extract as green inhibitor

In this study, we investigate the effect of aqueous extract of Eucalyptus globulus leaves (EGL) as a new green inhibitor on the precipitation of calcium carbonate (CaCO3) by using the rapid controlled precipitation method in synthetic solution. The EGL inhibitory characteristics were studied using several parameters including pH, calcium, and bicarbonate ions concentrations. The obtained results revealed that the inhibitory capacity of the EGL extract is proportional to its concentration. The total inhibition of CaCO3 precipitation was achieved after adding a low concentration of 75 mg/L. Moreover, the precipitation threshold of CaCO3 occurs at a higher germination time and lower supersaturation coefficient with a dissolved CO2 outgassing rate. The mechanism of inhibition scaling by EGL was proposed. Therefore, E. globulus leaves could be taken as a novel scale inhibitor on reverse osmosis membrane.