The formation of sparingly soluble and insoluble inorganic salts (i.e., scale deposits) is a major problem an industrial and domestic setting. To control scale deposits, chemical scale inhibitors are commonly used. Commercial antiscaling agents include polyelectrolytes that dissociate phosphonates, carboxylates, and sulfonates anionic groups. However, it is imperative to identify highly efficient polymeric inhibitors and environmentally friendly antiscalants, in particular, to replace phosphonate inhibitors due to their environmental risks. Certain polypeptides with charged groups have been extracted from organisms and found to efficiently control the nucleation and crystallization of minerals. Their structures are attractive models for better understanding the inhibitor-mineral interactions and designing next generation antiscalants. Antifreeze polypeptides (AFPs) from cold-adapted organisms (e.g., fish, insects, and plants) can inhibit the nucleation and crystallization of ice and some non-ice like compounds. Calcium carbonate (CaCO3), a common scale deposit, is a scalent of interest in this study. We investigate the effects of AFPs on the inhibition of calcium carbonate formation via adsorption to the compound’s surface, thus controlling nucleation and crystal growth of the calcium carbonate scale deposits. Two beetle AFPs from Dendroides canadensis (DAFP) and Tenebrio molitor (TmAFP) are prepared and studied here. These AFPs are repeat proteins having regular spaced charged residues on their surfaces and show their effects on the formation of calcium carbonate. We correlate the charge and molecular properties of the polyelectrolytes with their efficiencies in inhibiting the scale crystal formation. Our results provide better understanding for scale control as well as new designs for green antiscalants. Acknowledgements Acknowledgment is made to the donors of the American Chemical Society Petroleum Research Fund for support of this research. JL and AK thank the support from the National Institutes of Health Minority Biomedical Research Program-Research Initiative for Scientific Enhancement (MBRS-RISE) Undergraduate Fellowship (GM061331). We thank Dr. John Duman (U Notre Dame) and Dr. Peter Davies (Queen’s U) for providing the cDNAs of DAFP and TmAFP. We thank Sona Mnatsakanyan and Uriel Rivera for assisting AFP preparation.

Effects of antifreeze polypeptides on calcium carbonate crystallization

251st National Meeting (2016)

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