Chemical and electrochemical study of the inhibition of calcium carbonate precipitation using citric acid and sodium citrate

Abstract

This work investigated the inhibitive effect of citric acid (CA), sodium citrate (SC), and their mixture (CA–SC) on the CaCO₃ scale. The study was carried out using chronoamperometry, impedancemetry, and fast-controlled precipitation methods. The electrochemical study showed that CA provides a slight inhibition of CaCO₃ deposit at a concentration of 70 ppm on stainless steel surface. The use of SC alone inhibits very little the formation of scale. The use of the mixture (50% of CA and 50% of SC) with small concentration led to significant inhibition of the CaCO₃ formation. The deposits formed were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The XRD showed that the intensity of the preferential orientation (1 0 4) corresponding to crystallographic plans of calcite decreases and the SEM demonstrated a decrease in calcite crystal size from 10 to about 2 μm.

Keywords:

• Calcium carbonate deposit
• Inhibitor
• Citric acid
• Sodium citrate

Acknowledgment

This research was financially supported by University of Sétif-1-Algeria (Project J0101220100076).