Scale inhibition effect of Hylocereus undatus solution on calcium carbonate formation

•H. undatus and citric acid are green inhibitors.•The antiscalant properties were tested by using FCP and chronoamperometry.•The scale inhibition effects in solution and on a surface have been examined. In this paper, the inhibiting properties of an aqueous solution containing Hylocereus undatus towards CaCO3 formation were studied by using fast controlled precipitation and chronoamperometric methods, in order to study the calcium carbonate formation in solution and on a metallic surface, respectively. As a purpose of comparison, the antiscaling properties of citric acid were studied in the same experimental conditions. The results obtained by fast controlled precipitation method showed that Hylocereus undatus solution was more efficient than citric acid to inhibit CaCO3 formation in solution (optimal concentrations of 20 and 24 mg L−1, respectively). By using the chronoamperometric method, a concentration of citric acid at 160 mg L−1 was required to totally prevent the precipitation of CaCO3 whereas it was 180 mg L−1 for Hylocereus undatus solution. The morphology analysis by scanning electronic microscopy and X-ray diffraction revealed that vaterite was favored in the presence of Hylocereus undatus solution, whereas a mixture of calcite and vaterite was obtained with citric acid.