College of Civil Engineering, Yantai University, Yantai, 264000, China.
Environ Sci Pollut Res Int. 2022 Apr;29(18):26675-26687. doi: 10.1007/s11356-021-17809-4. Epub 2021 Dec 2.
To explore the migration law of magnesium ions (Mg) during freezing and melting processes, laboratory simulation experiments involving freezing and melting were carried out to investigate the influence of ice thickness, freezing temperature, initial concentration, and initial pH on the distribution of Mg in the ice-water system. The distribution coefficient "K" (the ratio of the Mg concentration in the ice layer to the Mg concentration in the water layer under ice) was used to characterize the migration ability of Mg. The results showed that during the freezing process, the concentration distribution of Mg in the ice and water two-phase system was as follows: ice layer < water before freezing < water layer under ice; in other words, it migrated from ice layer to the water layer under ice. "K" decreased with increasing ice thickness, freezing temperature, initial concentration, and initial pH; the higher the ice thickness, freezing temperature, initial concentration, and initial pH were, the higher the migration efficiency of Mg into the water layer under ice was. During the melting process, Mg was released in large amounts (50-60%) at the initial stage (0-25%) and in small amounts (25-100%) uniformly in the middle and later periods. According to the change of Mg concentration in ice melt water, an exponential model was established to predict Mg concentration in ice melt period. The migration law of Mgduring the freezing and melting process was explained by using first principles. Graphical abstract.
为了探索镁离子（Mg）在冷冻和融化过程中的迁移规律，进行了涉及冷冻和融化的实验室模拟实验，以研究冰厚、冷冻温度、初始浓度和初始 pH 值对冰-水系统中 Mg 分布的影响。分布系数“K”（冰层中 Mg 浓度与冰下水层中 Mg 浓度的比值）用于描述 Mg 的迁移能力。结果表明，在冷冻过程中，Mg 在冰-水两相系统中的浓度分布如下：冰层 < 冷冻前的水层 < 冰下水层；换句话说，它从冰层迁移到冰下水层。“K”随冰厚、冷冻温度、初始浓度和初始 pH 值的增加而降低；冰厚、冷冻温度、初始浓度和初始 pH 值越高，Mg 向冰下水层的迁移效率越高。在融化过程中，Mg 在初始阶段（0-25%）大量释放（50-60%），在中期和后期均匀释放少量（25-100%）。根据冰融化水中 Mg 浓度的变化，建立了一个指数模型来预测冰融化期间 Mg 的浓度。通过运用第一性原理解释了 Mg 在冷冻和融化过程中的迁移规律。
