Superspreading metal–organic frameworks modified interface for high-performance tritiated wastewater separation: Experiments and CFD simulation studies

Abstract

The tritiated water distillation method can inherently safely treat tritiated wastewater, but the separation efficiency is low, and there is limited understanding of the gas–liquid two-phase countercurrent distillation process that affects its separation performance. In this study, tritiated water distillation experiments with metal–organic frameworks (MOFs)-modified superspreading interface and computational fluid dynamic (CFD) simulations were conducted to investigate the influence of contact angle on gas–liquid two-phase interfaces and liquid holdup, as well as its impact on separation performance. A distillation column with a length of 1 m had a smaller height equal to a theoretical plate (HETP) of 3.0 cm, and higher separation performance than non-modified packing with HETP of 7.2 cm. The volume of fluid (VOF) method with the high-resolution interface capturing (HRIC) scheme was used to reconstruct the gas–liquid interface and the accuracy of CFD simulating was validated by droplet spreading experiment. CFD simulations demonstrated that the gas–liquid interface area increased from 34.9 m2/m−3(−|−) to 498.5 m2/m−3(−|−) with the contact angle decreasing from 90° to 0°. When the reflux rate increases from 85 kg m−2h−1 to 425 kg m−2h−1, the liquid holding capacity of the column remains stable at about 10 %, and the phase interface area remains stable at about 500 m2/m−3(−|−) for the MOFs-modified column. This research increased the understanding of the influence of surface wetting on the performance of tritiated water distillation and had potential applications for other gas–liquid two-phase flow separation processes.