High-Temperature-Resistant Scale Inhibitor Polyaspartic Acid-Prolineamide for Inhibiting CaCO3 Scale in Geothermal Water and Speculation of Scale Inhibition Mechanism

An excellent high-temperature-resistant scale inhibitor, polyaspartic acid-prolineamide (PASP-Pro), was synthesized by polysuccinimide (PSI) and L-prolineamide (L-Pro), then characterized 1H-NMR FTIR analysis. The inhibition performance of PASP-Pro on CaCO3 precipitation studied at different temperatures through static tests; the same time, influence crystallization process investigated combining electrical conductivity test solution with characterizations. suitable synthesis evaluation conditions for were obtained, a possible multi-stage mechanism suggested. has better thermal stability high-temperature (exceeds 87% after pretreatment 150 °C) than PASP. In addition, exhibited promising anti-scaling property inhibiting CaCO3; induction period nucleation prolonged nearly four times. It found from XRD patterns that vaterite, an unstable crystalline phase, gradually emerged addition inhibitors, aragonite crystals are clearly observed in SEM images. Finally, PASP-based inhibitors proposed, including coating impurities, electrostatic repulsion, dehydration rearrangement crystallization.