Towards eco-friendly alternatives to prevent CaSO₄·2H₂O scale formation in water industrial systems: A combined experimental study and Monte Carlo simulations

Scale deposits, particularly calcium sulfate (CaSO4·2H2O), pose a major challenge to the efficiency of water industrial systems. The present study explores the potential of quinic acid (QA), a polyphenol of plant origin, as a promising eco-friendly and sustainable inhibitor for CaSO4·2H2O scale. The efficacy of QA was assessed using the NACE assay, complemented by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses to study crystal structure and deposit morphology. Monte Carlo simulations were carried out to confirm the experimental results. Experimental results revealed that quinic acid (QA) has considerable potential to inhibit the process of calcium sulfate scale precipitation. The inhibition efficiency increased in proportion to the concentration of QA, reaching 98% at a concentration of 2.7 mg·L^–1 QA. SEM and XRD analyses reveal that QA not only prevents scale formation, but also modifies the morphology of CaSO4·2H2O crystals, disrupting their regular growth. Monte Carlo simulations confirm these experimental observations, predicting stronger adsorption of QA at different crystal surfaces as follows: gypsum(111) > gypsum(110) > gypsum(010). The demonstrated efficacy of QA against calcium sulfate scale, in addition to its eco-friendly nature, makes it a promising alternative to traditional inhibitors.