Electrodeposition of a calcareous layer: Effects of green inhibitors

The reduction of mineral scale is a challenge in many industrial fields and environmental issues relating to eutrophication are leading industry to develop environmentally friendly solutions to scale control. The effects of three green (carboxymethyl inulin (CMI), polymaleic acid and polyaspartic acid) and one non-green (polyphosphinocarboxylic acid (PPCA)) scale inhibitors on calcium carbonate nucleation and growth have been studied using electrodeposition. The study of chronoamperometry associated with deposition for a duration of 24 h has pointed to some important information relating to the interactions occurring between the inhibitors and the metal surface. PPCA, polymaleic acid and polyaspartic acid are surface active and 4 ppm of these inhibitors generated a significant reduction in the weight of calcium carbonate deposition. The study of the current density variation did not show any obvious interactions between the metal surface and the CMI. Microscopic observations after 4 and 24 h have shown that the inhibitors generate specific changes in the crystal morphology and that PPCA, CMI and polyaspartic acid lead to vaterite formation in preference to calcite seen in uninhibited solutions.