Magnetite is a major corrosion product of carbon steel that forms deposits in the steam generators in water-cooled nuclear reactors. Sulfate is present as an impurity in the steam generator feed water and accumulates in the magnetite deposits, leading to formation of acidic crevices, corrosion and stress corrosion cracking of steam generator tubing. Reliable adsorption data are required to understand material degradation of steam generator tubing. Sulfate adsorption onto magnetite has been studied at temperatures from 25 to 300 °C as a function of pH, and chloride and sulfate concentrations. The results show that adsorption decreases with increasing pH and ionic strength, and adsorption followed the Langmuir adsorption isotherm. Overall, sulfate adsorption onto magnetite is endothermic and the enthalpy of adsorption depends on the pH and ionic strength of the solutions. The adsorption behavior of sulfate onto magnetite is explained through outer-sphere and inner-sphere adsorption.

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高温下磁铁矿吸附硫酸盐的动力学和热力学

磁铁矿是碳钢的主要腐蚀产物，会在水冷核反应堆的蒸汽发生器中形成沉积物。硫酸盐作为杂质存在于蒸汽发生器给水中并在磁铁矿沉积物中积累，导致形成酸性裂缝、蒸汽发生器管道腐蚀和应力腐蚀开裂。需要可靠的吸附数据来了解蒸汽发生器管道的材料降解。在 25 至 300 °C 的温度下，研究了磁铁矿吸附硫酸盐与 pH 值、氯化物和硫酸盐浓度的关系。结果表明，吸附量随着pH值和离子强度的增加而降低，并且吸附遵循Langmuir吸附等温线。全面的，硫酸盐吸附在磁铁矿上是吸热的，吸附焓取决于溶液的 pH 值和离子强度。通过外球和内球吸附来解释硫酸盐对磁铁矿的吸附行为。