Research on Growth Behavior of Calcium Carbonate Scale by Electrochemical Quartz Crystal Microbalance

An electrochemical quartz crystal microbalance (EQCM) was used to evaluate the scaling behavior of CaCO3 using an electrochemical method in which cathodic potential was applied to the working electrode. Accelerated scaling experiments were performed by varying the temperature and applied potential in a 3.5% NaCl solution containing 200 mg/L Ca2+ and 610 mg/L HCO3-. Scale inhibition efficiencies were also compared in the absence and presence of four scale inhibitors, including amino trimethylene phosphonic acid (ATMP), sodium hexametaphosphate (SHMP), 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) and copolymer of phosphono and carboxylic acid (POCA). For further investigation of the scale inhibitors' inhibition properties, the growth kinetics of CaCO3 scale were investigated by injecting scale inhibitors during the scaling formation process. Additionally, to understand the mechanism of scaling inhibition, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were undertaken to analyze and compare the morphologies, particle sizes, and crystal growth of CaCO3 scale at different conditions.