气-液界面处疏水碳酸钙纳米颗粒的分布行为及其对传质过程影响的研究

在纳米碳酸钙原位改性、碳酸钙基润滑油清净剂制备等过程中，疏水碳酸钙纳米颗粒易富集在气-液界面处并对气-液传质过程造成影响。为揭示疏水碳酸钙纳米颗粒的分布行为，并量化其对传质过程的影响程度，提出利用探索界面处颗粒层流变行为的方法来确定疏水性碳酸钙纳米颗粒在气-液界面上的吸附量，并预测其对传质过程的影响。一方面，通过对界面处疏水碳酸钙颗粒层进行流变测量，量化不同疏水性颗粒加入条件下界面处的表面压力；另一方面，利用膜分散微反应器进行Ca（OH）₂溶液-CaCO₃疏水颗粒体系吸收CO₂的传质行为研究。研究结果表明，碳酸钙纳米颗粒的疏水性和颗粒表面浓度会直接影响颗粒的分布状态，进而改变界面处的表面压力，最终导致传质效率出现差异。当颗粒达到临界浓度、颗粒层呈现不可压缩的流变状态时，气-液传质系数会降低约一个数量级（从10^-3 m/s到10^-4 m/s）。此外，还进一步提出了气-液界面处表面压力与液相中碳酸钙纳米颗粒疏水性和表面浓度关系的计算式，进而确定了气-液体系原位合成改性碳酸钙纳米颗粒的适宜操作范围。

Distribution of hydrophobic CaCO3 nanoparticles at a gas-liquid interface and its effect on mass transfer

This study presents a novel approach to quantify the adsorption of hydrophobic CaCO₃ nanoparticles at a gas-liquid interface and predict the corresponding mass transfer processes. Rheological measurements of the layers formed by the hydrophobic particles were carried out. A simulated mass transfer experiment of CO₂ absorption in the Ca(OH)₂-CaCO₃ system was carried out with efficient mixing ensured by using a membrane dispersion microreactor. The effects of particle hydrophobicity on the layers in the two processes were determined. The results show that particle hydrophobicity and surface density both have a strong influence on the properties of the layers. The behavior of the layers in the rheological and mass transfer experiments was similar, as demonstrated by the comparable critical surface concentrations. Our rheological measurement approach can be used to determine the optimum operating conditions of gas-liquid slurry systems for the synthesis of in-situ modified nanoparticles.