The role of electrical current mode in calcium carbonate deposition on conductive carbon nanofiber–epoxy coating

Abstract

AbstractCalcium carbonate is one of the most common scaling minerals. In this paper we have used different electrical current modes (direct current [DC], pulsed DC, and alternating current [AC]) to control the amount, morphology, and distribution of calcium carbonate deposit on electroconductive epoxy/carbon nanofiber (CNF) coating. The effect of different current modes on surface scaling was visualized using scanning electron microscopy. It has been shown that both AC and DC anodic polarization limited scale deposition on epoxy/CNF coated surfaces, although the mechanisms of scale inhibition during AC and DC polarization were different. DC polarization of the coating at +2 V resulted in the smallest scale buildup without leading to coating degradation, while DC polarization at potentials as high as +5 V caused the coating to degrade. Interestingly, application of pulsed DC with high pulse frequency (50 Hz) inhibited the degradation. The type of current applied affected also the morphology of the precipitate at the cathode. The results presented in this work show, for the first time, how different modes of electrical current applied to electroconductive composite coatings can be used to control the morphology and distribution of calcium carbonate scale, and how the organic coating degradation at high polarization potentials can be avoided.