Abstract
The authors report for the first time on temperature-dependent extracellular synthesis of nanoscale calcium pyrophosphate (α dicalcium phosphate and β dicalcium phosphate) crystals using thermophilic Bacillus sp., which is isolated from marine environment rocks. This calcium-precipitating bacterium was identified by biochemical test and microbiological aspects of calcium pyrophosphate crystals and their role on corrosion and these biogenic calcium crystals were analyzed using XRD, FT-IR techniques. The corrosion behavior of calcium precipitating bacteria (CPB) on mild steel was studied by the electrochemical method (polarization and impedance). The calcium pyrophosphate crystals formations by bacteria reduces the cathodic corrosion current in CPB-1, 2, 3 and CPB-4 reduces anodic corrosion current, where resistance was lower in the presence of bacteria. It is claimed that the temperature is one of the causative factor for calcium carbonate crystals formation and corrosion in marine water system.
Acknowledgments
The authors thank Mr. Rathish Kumar, Miss. S. Krithika, and Mrs. Nalini of the Instrumentation Division; and Mr. C. Dandapani and Miss. B. Sujitha for their help during lab work. They also thank CECRI for their assistance in the utilization of TEM, XRD, and FTIR facility.