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The Hamma groundwater provides water to Constantine, a city in eastern Algeria. The high concentration of calcium ions (136 mg/L) and hydrogen carbonate (442 mg/L) accounts for the strong scaling power of the water. This study is the first attempt to mix green inhibitors randomly to determine which is the most effective. The use of three new mixtures gallic acid+quercetin, quercetin+alginate, and gallic acid+alginate) to decrease or to prevent calcium carbonate formation is the main topic of this research. Due to their low environmental impact, these mixtures have proven to be effective green scale inhibitors. The inhibition efficiency occurs at extremely low concentrations: gallic acid+quercetin (6mg/L), quercetin+alginate (60mg/L), and gallic acid+alginate (3mg/L). The inhibition effects of these mixtures are evaluated using electrochemical techniques (chronoamperometry and impedancemetry). The results showed that the most efficient scaling inhibitor is gallic acid+alginate since it produced positive results at a lower dosage (3mg/L) than the other mixtures. [ABSTRACT FROM AUTHOR]

In this study, fast controlled precipitation (FCP) and chronoamperometry (CA) methods were performed to evaluate the influence of the magnetic treatment at 0.70 T, upon the scale formation in synthetic solutions (hardness 25 °F), exposed to a static magnetic field for different exposure times. According to FCP results, homogeneous CaCO3 precipitation rates in treated solution were lower than those in the absence of the magnetic field. It has been found that the memory effect can last up to 24 h after the magnetic treatment even if it decreases over time. As purpose of comparison, CA method was applied to investigate the influence of the magnetic treatment on heterogeneous CaCO3 precipitation. The magnetic field effect increased with the increasing exposure time. The obtained scale, characterized by scanning electronic microscopy and X‐ray diffraction, was formed by a mixture of calcite and aragonite in the presence of magnetic field. [ABSTRACT FROM AUTHOR]

In this study, the properties of quercetin (3,3′,4′,5,7‐pentahydroxyflavone) solution towards CaCO3 formation were evaluated by using chronoamperometry (CA) and impedance measurements. Quercetin a flavonoid present in plants as a secondary metabolite. Using CA, precipitation of CaCO3 was totally inhibited by adding 2 mg/L of quercetin (T = 30°C). The same result was obtained by impedance measurements. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were used to characterize the calcium carbonate scale without or with quercetin treatment. The predominant crystalline structure corresponds to a mixture of calcite and aragonite. [ABSTRACT FROM AUTHOR]

Scaling process is the main problem encountered in industrial plants using water. Several factors (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition) can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main components of scaling. In addition, some foreign ions added can considerably modify the scaling rates. In this work, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (=1 mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solution containing 5 and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation more efficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonate nucleation by changing the morphology of CaCO3 crystals. [ABSTRACT FROM AUTHOR]