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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.

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It is hardly replaced one carbon in benzene with other heteroatom by direct breaking of the particularly strong C=C bond in benzene not only due to the high dissociation energy of benzene ring but also due to more limit to the C–H activation. Direct ring‐open of benzene has been mainly limited to the high dissociation energy. In our former research, we have found an ion‐molecule reaction via simple replacement of one carbon in benzene with nitrogen atom. But the reaction mechanism still remains unresolved. Herein, we demonstrate the direct ring‐open mechanism in benzene through theoretical study of potential energy surface, in which benzene attacked by H2NO2+ ion with the formation of pyridine. Reaction mechanisms have been confirmed that ring‐open in benzene involves two steps that include attacking reaction and isomerization process. It is found that H2NO2+ ion trend to attack benzene with dissociation of H2O firstly. The isomerization process happens is most favorable in the evolution potential energy surface of the isomer C6H5N(H)O+. It has been verified of the theory, which is consistent with the experiment. The mechanism derived from this study may provide guidance for promoting the reaction yield and selectivity of aromatics ring‐open reaction.