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Open AccessArticle

Crystallization of CaCO3 in Aqueous Solutions with Extremely High Concentrations of NaCl

School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China
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Authors to whom correspondence should be addressed.
These authors contributed equally.
Crystals 2019, 9(12), 647; https://doi.org/10.3390/cryst9120647
Received: 20 November 2019 / Revised: 1 December 2019 / Accepted: 5 December 2019 / Published: 6 December 2019
(This article belongs to the Special Issue Carbonates Volume II)
The effect of NaCl at extremely high concentrations from 3.5 to 14 wt. % on the crystallization of CaCO3 was investigated in depth. The static test experiment verified that the Ca2+ retention efficiency (η) of NaCl on CaCO3 scale increased from 31.06% (3.5 wt. %) to 41.56% (14 wt. %). Based on the calculation of supersaturation rations, the high concentration of NaCl could reduce the activity coefficients of [Ca2+] and [CO32−], thus reducing the actual concentration of CaCO3. The CaCO3 deposition rate constants (k) showed that NaCl slowed down the rate of CaCO3 crystallization. The X–ray diffraction (XRD) testing disclosed that the growth of (1 0 4) and (1 1 0) faces from calcite was impeded, while the formation of (1 1 1) face from aragonite was induced by the increasing concentration of NaCl. The inductively coupled plasma optical emission spectrometry (ICP–OES) results indicated that Na+ could be doped into CaCO3, leading to the one–dimensional crystal growth. It was further proved that NaCl heightens the efficiency of the typical phosphate inhibitors (2–phosphonobutane–1,2,4–tricarboxylic acid (PBTCA) and 1–hydroxyethane–1,1–diphosphonic acid (HEDP)) on prohibiting the scale of CaCO3. View Full-Text
Keywords: calcium carbonate; NaCl; lattice distortion; PBTCA; HEDP calcium carbonate; NaCl; lattice distortion; PBTCA; HEDP
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Qian, M.; Zuo, Y.; Chen, Z.; Yin, X.; Liu, Y.; Yang, W.; Chen, Y. Crystallization of CaCO3 in Aqueous Solutions with Extremely High Concentrations of NaCl. Crystals 2019, 9, 647.

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