Abstract

Calcium carbonate (CaCO3) scaling remains a major challenge in industrial water systems, causing operational inefficiencies, corrosion, and high maintenance costs. Although water-soluble chemical inhibitors have been widely studied, many are phosphorus-based and contribute to environmental eutrophication. In line with current trends toward sustainable nanohybrid materials, nanoparticles have emerged as an alternative for CaCO3 scale inhibition due to high surface reactivity and the possibility of recovery by filtration and/or separation. However, polymer-based nanoparticles for CaCO3 inhibition remain scarcely explored. In this work, novel sulfonated polyetherimide (SPEI) nanoparticles are proposed as a functional polymer-based nanohybrid platform to inhibit CaCO3 formation in aqueous systems. Both SPEI and PEI nanoparticles were synthesized via the nanoprecipitation method followed by dialysis, resulting in nanoparticles with an average diameter of approximately 50 nm and a negatively charged surface. The inhibitory performance of the samples was assessed using automatic potentiometric titration (APT), a technique that allows real-time monitoring of both prenucleation and nucleation processes. The results revealed that SPEI nanoparticles delayed CaCO3 nucleation, extending the nucleation time to 17,340 s at a concentration of 10 mg/L. This inhibitory effect exceeded that observed for the nonsulfonated PEI nanoparticles (10,980 s at 20 mg/L) and the control samples (12,145 s). Furthermore, SPEI nanoparticles controlled CaCO3 polymorphism by promoting vaterite formation at the expense of calcite, a desirable outcome for scaling mitigation. The SPEI nanoparticles exhibited a strong inhibitory effect on CaCO3 crystallization, making them promising candidates for preventing scale deposition in pipelines and heat exchangers in various industrial applications.